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 August 17, 2017 Lolo Peak Fire

Lolo Peak Fire, August 17, 2017. Photo by Shannon Edney

Smoke-Ready Blog - 2020

Use these links to skip to the blog post you want to read!

7/6/20: An annual summer tradition

7/13/20: The wonderful world of filtration

7/16/20: Portable air cleaners

7/17/20: Make your own air cleaner!

7/21/20: Using your HVAC system to clean your indoor air

7/24/20: Coping with summer heat during smoke season

8/3/20: Considerations for commercial spaces

Smoke-Ready Blog - 2019

6/26/19: It's time to become wildfire smoke-ready! 

7/9/19: Creating cleaner indoor air with portable air cleaners 

7/18/19: Using your HVAC system to clean your indoor air

7/23/19: Coping with smoke and heat

 

Resources

Websites

Climate Smart Missoula's wildfire smoke pages:

www.montanawildfiresmoke.org

https://www.missoulaclimate.org/wildfire-smoke.html

Includes great resources and some recommendations for creating cleaner indoor air spaces as well as info about air quality and health.

EPA's smoke-ready toolbox

https://www.epa.gov/smoke-ready-toolbox-wildfires

California's list of certified air cleaners

https://ww2.arb.ca.gov/our-work/programs/air-cleaners-ozone-products/california-certified-air-cleaning-devices

Some air cleaners produce ozone, which is harmful to your health.  Before you purchase an air cleaner, make sure it's certified by California - they only certify air cleaner that do not produce ozone.

Montana's Today's Air website

http://svc.mt.gov/deq/todaysair/

Check the current air quality at air monitors around the state.

 


 

Handouts (pdf downloads)

Using your central air handler to create cleaner indoor air (Source: Climate Smart Missoula)

Residential Guide to Air Cleaners in the Home (source: EPA)

Indoor air filtration (source: EPA)

 


Smoke-Ready Blog

August 3, 2020 

Considerations for Commercial Spaces

For many years, the conventional wisdom during wildfire smoke events was that people should go indoors, and if they didn’t have air conditioning or their own air cleaners, they should go to the mall, or movie theater or museum or library, etc.  The thinking behind this is pretty simple: These places will have air conditioning, so they must also have cleaner air, right? 

Well, it depends. During the 2017 wildfire season, Climate Smart Missoula placed air sensors inside buildings around town and found the indoor air quality frequently matched the outdoor smoke levels. When you think about how commercial HVAC systems are designed to deliver fresh air inside, it should not surprise you that, in the absence of good filtration and a system set up to protect indoor air quality, the air pollution levels can quickly match what we find outside. This contrasts with a home environment, where you can shut the doors and windows and keep smoke out for at least several hours, perhaps up to a day.  (Smoke levels in a residential setting can take longer to match outdoor levels because, if your doors and windows are closed, you are not actively bringing air inside.  See my previous blog posts to learn about protecting your residential indoor air quality during wildfire season!) 

The Health Department is currently working with the EPA and UM partners on a study to examine indoor air quality around Missoula County during wildfire season.  We anticipate a more robust set of recommendations following this study, but based on studies and assessments in other areas, we can make some general recommendations for improving indoor air quality during smoke events. 

Before we get into this, I am not an engineer. I have friends who are engineers and I survived a year of physics in undergrad (an experience that underscored my commitment to avoid engineering as a profession). This does not an HVAC-expert make. However, because I obsess over wildfire smoke, I’ve read many of American Society of Heating, Refrigerating and Air-Conditioning Engineers’ (ASHRAE’s) guidelines and standards and have had real engineers walk me through HVAC operations.  I have also spent time reading HVAC tech maintenance tips online. (Don’t look at me like that. It beats doom scrolling.) And, because accuracy is important, I had local expert, engineer and ASHRAE Life Member Tom Javins edit this post. Thank, Tom! 

Here’s my non-engineer’s interpretation of how they work: 

Commercial HVAC systems serve multiple purposes. They provide climate control (heating or cooling), balance the building’s pressurization, and provide fresh air to avoid the buildup of carbon dioxide and other unpleasant gases and pollutants humans and their indoor activities emit into the air. (Humans can by filthy, yo.) The primary way they achieve these goals is by drawing fresh air inside and heating or cooling air as needed. During the summer months, some systems use fresh air at night, much like how those of us without air conditioning open our windows to cool the inside of our homes. When the external temperatures rise, the dampers close to a minimum setting, and rather than draw lots of warm air inside, the system will recirculate the inside air across evaporative cooling coils to maintain the desired internal temperature. The dampers may reopen to draw fresh air in for additional ventilation or when the external temperature drops enough to warrant bringing in fresh air for cooling. 

When fresh air enters the unit, it may go through a prefilter that keeps birds and bugs from gumming up the works and then mixes with return air from the building and passes through a particle filter that is in place more to keep the guts of the HVAC clean than to protect human health.  After this nominal cleaning, it goes across the evaporative (i.e. cooling) coil before it is supplied to the building to keep you comfortable. Airflow through the building is managed via ductwork, vents, etc. that we are not going to get into, but which influence building pressurization and the ability of the HVAC motor to maintain the required airflow across the cooling coils.  If the mass of air flowing across the coils drops too much, the coils can ice up.  Ice sounds pretty good when it’s hot outside, but if your cooling system ices over, you have a serious problem.  When you are actively cooling the air, you need to maintain a certain amount of airflow to prevent compressor failure and a large repair bill.  

This is a very simplified description.  The key point is these units either draw outside air in, recycle internal air, or do a combination of fresh and recycled air. No matter the source, all the air will pass through filters before being sent into the building.  However, as we’ve discussed before, all filters are not created equal. The goal for wildfire season is for air to pass through, at a minimum, a MERV 13 filter.  The current ASHRAE standard for commercial buildings is a MERV 8.  A MERV 8 filter will do a good job keeping larger particles from coming into the HVAC unit and they are cheaper than MERV 13s. This means in almost any commercial building around town, you’ll find MERV 8s.  We know. We looked 

MERV 8 filters are perfectly fine most of the year. However, they are not designed for capturing the very fine particles in wildfire smoke.  During a smoke event they will catch some particles, but not nearly as much as a better filter. A MERV 13 filter has been tested to remove 50% of the very fine particulate matter in air with each pass through a filter.  A MERV 8 filter will catch far less. 

Because better filters can impede air flow, it is not uncommon for folks to be reticent to upgrade their filters and potentially risk their HVAC system.  To that point, a few things to know: 

  1. The pressure drop between a MERV 8 and MERV 13 is not huge. It’s there, but it’s not as significant as making the jump from say, a MERV 4 to a HEPA filter. 
  2. LEED-certified buildings should have HVAC systems that are designed for MERV 13 filters. 
  3. Even if you don’t have a LEED-certified building, you may be able to use a better filter in your system.  You will need to examine your manual and do some checks to make sure your system can maintain a desired airflow. You may need to adjust another part of your system (such as sagging ductwork, damper settings, dirt-clogged venting or dirty coils that reduce air flow pressure) to accommodate a MERV 13 filter. 

An important note: You can’t assume that because your air is being cooled everything is hunky dory in the AC unit.  We’ve found filters that hadn’t been changed in years and were so clogged air went right around them without being cleaned. We’ve found an air conditioning unit that still had the MERV 4 filters it came with from the factory. We’ve also found units that were designed for MERV 13 filters rocking MERV 8s because they’re cheaper. 

So, before you enter wildfire season, take some time with your HVAC technician to find out what you need to do to optimize the filtration in your unit.  Happily, ASHRAE recently released guidance for schools and universities navigating the era of COVID, and there’s an entire section devoted to upgrading filtration to MERV 13s starting on Page 22. This is a great resource for anyone who wants to provide their building occupants with cleaner indoor air and need a place to start. You do not have to be a school or university to use the information. Check it out and share it widely!  

Back to the layperson’s guidance, here are some things to check off: 

  1. Can this unit use MERV 13 filters? Check the manual. If your building is LEED certified, you should be able to use MERV 13 filters without any alterations. 
  2. A skilled HVAC technician will be able to check and see if installing MERV 13 filters causes too much pressure drop for the motor. Beyond the filters in the unit, system characteristics such as the duct configuration and extra internal filters can impact pressure drop. 
  3. Make sure your filters are properly seated and air cannot easily flow around them. 
  4. Make sure the filters are clean 
  5. Maintain positive pressure in the building. If you create negative pressure, you will draw dirty air in through cracks around windows, doors, etc. 
  6. Limit fresh air intake. Ideally, you’ll only bring fresh (in this case, dirty) air in when necessary to lower carbon dioxide levels or maintain positive pressure. 
  7. Limit door and window use as much as possible to limit smoke intrusion 
  8. When the smoke clears, open the fresh air intake and let the clean air in! 

Note: you may not be able to use MERV 13s, either because your system can’t handle the pressure drop or your filter banks are a weird size and you’d have to custom-order the MERV 13s, and who has time for that? Even if you can’t use MERV 13s, ask about MERV 11 or 12 – they aren’t as good as a MERV 13, but they’re still an improvement and will collect more fine particulate than a MERV 8.  Make sure the filters you do have are clean and seated correctly and limit the fresh air intake as much as possible.  Then, if you want to take steps to clean your indoor air, use portable air cleaners with true HEPA filters or DIY fan/filter combos to clean the air in individual rooms. 

Finally, this is the era of covid, and the current guidance for HVAC operation is to stop recycling the inside air and go to 100% fresh air intake. However, the guidance also says to use MERV 13 filters and PACs with HEPA filters and to use caution drawing in outside air in polluted areas.  Wildfire smoke can be immediately harmful to building occupants’ health. Whether you are drawing in outside air or recycling your indoor air, you need to clean it as best you can. 


July 24, 2020 

Coping with summer heat during smoke season

Full disclosure: Why yes, I am re-using a blog post again (with small updates). For those of you who don’t want to learn about air conditioners, here’s the summary: if you have a window air conditioner, portable air conditioner, open your windows at night, or have a central air handler that cannot use a better filter, you will need portable air cleaners with true HEPA filters or DIY fan/filter combos to keep you indoor air cleaner during smoke season. For those of you with newer, high efficiency central air conditioning systems that can run with better filters, remember to decouple your fan from your thermostat so air is continuously running through the filters.  Otherwise, your air will only be cleaned while it is being actively cooled.

Blog time.

We just got our first real taste of summer heat followed by lightning, and it’s coming back next week (the National Weather Service is expecting 90s next week with a chance of thunderstorms starting midweek).  That means it’s time to talk about air conditioning.  And smoke!  There’s always a way to work smoke into a conversation.  This is why air quality specialists make terrific (or terrible) dinner guests. 

With continuing hot temperatures and the likely return of wildfire smoke in the coming weeks, it’s important to make plans for keeping your house cool.  According to the Centers for Disease Control, every year more than 600 people in the United States are killed by extreme heat.  However, heat-related illnesses are preventable, and one of the steps you can take is cooling your home. 

I would be remiss in my air specialist duties if I didn’t remind ya’ll that air conditioners can be energy hogs, which is a no-no when we’re trying to confront climate change by reducing energy use.  However, your health is crazy important, so I’m not going to tell you not to use it.  Do try to limit your air conditioner use to the amount needed to keep your house at a safe temperature and as smoke-free as possible.  Climate Smart Missoula has some nifty tips for keeping your home cool(ish) in the summer: https://www.missoulaclimate.org/hotter-days-and-nights.html 

Do you have central air conditioning? Awesome!  If possible, bypass the fresh air intake when smoke arrives, upgrade your system’s filter (see the 7/13 and 7/21 posts on filters and HVAC systems), keep your doors and windows closed, and enjoy the cool, clean air.  Important note: not all air conditioning systems can cope with the pressure drop associated with better filters.  Newer, high efficiency air conditioning systems should be okay, but do your due diligence and consult with an HVAC technician before upgrading your filter.  If your air conditioning system can’t use better filters, your best route will be to place portable air cleaners with HEPA filters or DIY fan/filter combos in the rooms of your home where you’re spending the most time.

A lot of us do not have central air conditioning.  That leaves us with window air conditioners, portable air conditioners (those rolling things with giant hoses that send exhaust out the window), and the good old-fashioned method of opening windows at night and using fans to push hot air out and draw cool air in. Whichever method you use is personal preference, but the tricky thing here is smoke infiltration.  Opening windows at night works pretty well when it’s not smoky.  Unfortunately, the nice cool air that is so refreshing at night is the same cool air that traps smoke near the valley floor.  It’s not uncommon for us to see thick overnight smoke, and that smoke will move right into your home when you open your windows.  If you have no other option, it may be best to open your windows for long enough to cool your home, and then, once you’ve closed the windows, crank up your portable air cleaner(s) (PACs) or turn on your DIY fan/filter combo to remove the smoke.  It is very important to avoid heat stress.  It can feel like a lousy bargain – clean air or cool air, but if you have an appropriately sized PAC with HEPA filtration on hand, you should be able to clean the smoke out of a room relatively quickly. A DIY fan/filter combo will take a little bit longer than a HEPA PAC to clean the air, but as air recirculates through the DIY setup it will improve over time.

And now, a brief foray into window and portable air conditioners.  First, we need to talk very briefly about how air conditioners work.  Disclosure: I am not an air conditioning expert.  I don’t even play one on T.V.  I have, however, honed my googling skills.  After much trial and very little error, I recommend the search queries “How do window air conditioners work?” and “How do portable air conditioners work?” Don’t let anyone tell you we aren’t a full-service health department.

Moving on.

Air conditioners transfer heat from your inside air to the outside air in a process that involves a cool air cycle and a hot air cycle. In the cool air cycle, the air conditioner draws indoor air across cooling coils, transferring the heat from the air to the refrigerant in the coils.  The now-cooled air is released back into the room.  The heated refrigerant needs to be cooled down, so in a separate part of the machine, the air conditioner pulls outside air across the heated refrigerant.  The heat from the refrigerant transfers to the air and the machine sends the now extra-warm air back outside.  A properly installed window air conditioner should keep these two air cycles separate.  Inside air cycles across the cooling coils and is released back inside and outside air cycles across the heated refrigerant and is released back outside.

Here’s a nifty link to a site that describes the process in better detail: https://homeairguides.com/air-cooling/how-does-a-window-air-conditioner-work/

Here’s a snazzy diagram for those of us who like our air conditioner explanations in picture form: https://commons.wikimedia.org/wiki/File:Air_conditioning_unit-en.svg

Because window ACs recirculate room air, they generally keep indoor air in and outside air out.  However, some models have a feature that allows the user to bring in fresh air.  Check your model for a fresh air intake and be certain to close it during a smoke event.  Also, you will want to make sure the area around your window AC is as sealed as possible to limit smoke infiltration around the sides of the machine.  Once the area around the AC is sealed, peer into your window AC through the room-facing vents.  Can you see sunlight? Some ACs have Styrofoam dividers on their insides, and the seams aren’t perfectly sealed.  These small cracks let in sunlight and are also likely to let in some smoke. Also, if you have a jerry-rigged setup such as a window AC unit in a side-sliding window, you may need to basically treat your window AC unit as an open window.  In general, it’s going to be a good idea to keep an appropriately sized PAC running in whichever room has a window AC.

If you want to use your window air conditioner to help filter your indoor air, research your machine’s ability to function with an upgraded air filter.  Window air conditioners have filters, but they’re designed for catching dust and pet hair, not the fine particulate in smoke.  There are some aftermarket window air conditioner filters out there, but they can be a bit dodgy on specifics about particulate removal.  Also, you need to cautious about adding an upgraded filter to a window air conditioner because the increased resistance can put significant stress on the machine. If you choose to upgrade your filter, get the highest MERV-rated filter you can for your model of window air conditioner, and use your PAC with HEPA filtration or DIY fan/filter combo to clean whatever is left over.

Because of their design, portable air conditioners can be used with more window types than a window air conditioner, so they may be an option worth considering if you have side-sliding windows.  However, they tend to be considerably more expensive than window air conditioners and not all portable air conditioners are created equal.  Portable air conditioners come in two types: single and dual hosed.  In both types, the hoses bring in outdoor air to cool the refrigerant and send heated exhaust out the window. A single-hosed portable unit will use the same hose for both intake and outtake.  Because it can’t draw in enough outdoor air to cool its refrigerant, the single-hosed unit will also draw in your nice cool room air to cool itself down and send that air out the window.  This could be problematic during fire season because the process creates negative pressure in your home.  The negative pressure will pull outside air into your house through various nooks and crannies, and if it’s smoky outside, it may also pull smoke into your home.  Dual-hosed portable ACs avoid the negative pressure issue by having a hose dedicated to drawing outside air into the machine to cool the coils.  This way, only outside air is exhausted out the window – inside air stays inside and the pressure in your house should remain stable.  However, dual-hosed portable air conditioners tend to be quite a bit more expensive than single-hosed machines.  If you are using a portable air conditioner, try to seal the edges where the exhaust plate meets your window as much as you can.  Otherwise, there’s a good chance smoke will sneak in around the edges.   Use your PAC to clean out whatever smoke ends up inside.  This will be particularly important if you have a single-hosed portable AC. 

The take home message is this: You need to be able to cool your home, and there’s a good chance the process of cooling your home will introduce smoke into your breathing space.  If you have a PAC with true HEPA filtration or a DIY fan/filter combo you can reduce the amount of smoke that stays in your home.  In 2017, Climate Smart Missoula ran particulate sensors in a house that did not have air conditioning but did have PACs with HEPA filtration.  Yes, smoke came into the house overnight when smoke rolled into town.  However, within a couple hours of closing the windows and turning on the air cleaners, that house had some of the best air in Missoula. 

If you don’t have air conditioning and, based on your health, you can’t allow any smoke into your home, your best option may be to find somewhere else to be next time smoke rolls into town.  You may need to stay somewhere local with air conditioning and filtered air or leave the valley to find clean air. 

Stay cool and breathe safe!

 


July 21, 2020 

Using your HVAC system to clean your indoor air

In my last two updates I wrote about using portable air cleaners (PACs) and DIY fan/filter combos to create cleaner indoor air during smoke events.  Typically, folks will use PACs to clean individual rooms.  For those who want to have cleaner air throughout their entire house, they will either need to purchase multiple PACs, build multiple fan/filter combos, or use their central air handler or furnace fan to push air through a filter and distribute the air throughout their home.

(If you decide to go the PAC/DIY route, know that it isn’t going to move air throughout the house.  If you place a PAC in the living room, it’s not going to do a great job cleaning the air in the bedrooms down the hall even if the PAC is rated for a really large space and the doors are left open.  Air just doesn’t corner very well.)

Now, before we get into this, here is my disclaimer: I am not an HVAC technician.  I’ve spoken with some folks who know things and I’ve done a lot of reading, but this does not make me an expert. If you have questions about your specific air handler/furnace/air conditioner, etc., please talk to your HVAC technician.

Also, yes, this is another post from last year. If you read it enough times in 2019 to hold all the information in your heart, you have my permission to skip this blog and go for walk before it gets crazy hot this afternoon. If you, like me, forgot what was in it, read on!

Alrighty.  Let’s go.

It’s becoming more common these days for homes to be built with HVAC systems (heating, ventilation and air conditioning) that use central air handlers for cooling and/or heating. In addition to impressing the socks off this Montana child of the ‘80s (Air conditioning in a house???  That’s some fancy stuff right there!), the filters on air handlers can be handy tools for cleaning indoor air throughout your home during a smoke event.  Your duct work will deliver air to each room, which solves the cornering problem PACs face.

Note that If you have central air for heat, but not air conditioning, you can still clean your indoor air by turning your furnace fan on without the heat.

To get started, we need to dig into HVAC filters.  First, find where your filter(s) are housed in your HVAC system (note that some homes may have more than one air return and corresponding filter). Look at your filter.  Is it a flat panel? Is it washable?  Is it something you’d take outside, hose off and return to its casing? If so, and if want to use your HVAC to clean your air, you need a different filter.  A better HVAC filter will have a whole bunch of fabric pleats and cannot be washed.  Note that even if you have a filter with some pleats and you wouldn’t dream of washing it with a hose, there’s a good chance the filter currently sitting in your air handler is not going to remove fine particulate matter from smoky air.  Homes will generally have a filter that is MERV 6 or less, and you need to upgrade to at least a MERV 13 to get a filter that has been tested and shown to remove the tiny particles in wildfire smoke. 

I covered MERV ratings a few blogs ago. If you need a refresher, hop on over to post about the Wonderful World of Filtration!

Before you start using your central air system to clean your indoor air, there are some things you need to know and steps you need to take:

1.       Can your HVAC system handle a better filter?

Not all furnaces or air handles can deal with the added resistance from better filters.  The better the filter, the harder it is to pull air through it. Folks in the HVAC world call this the “pressure drop.” As you increase MERV, you also increase pressure drop.  If you aren’t sure if your HVAC can handle a better filter, talk to your HVAC technician.

2.       Thicker filters are better (but also more expensive).

Thick pleated filters (4 to 5 inches deep), will allow greater airflow through your air handler than 1-inch pleated filters.  This will reduce the energy required to pull air through the filter and will help with concerns about pressure drop.  Not all air handlers will have slots for these thicker filters, but if you can, aim for a thicker filter.

3.       Install your filter correctly.

There is an arrow on your filter.  It needs to point in the same direction as the airflow.

4.       Can air sneak around your filter? That’s a no-no!

Once you’ve slid the new filter into its slot, take a good, hard look at it.  Is it loose? Can air easily bypass the filter?  If air can move around the filter instead of through the filter, you won’t get much benefit from your fancy new filter.  You’ve basically put up pretty curtains but forgot to close the window.  Filter bypass is often caused by poorly fitting filters, poor sealing of filters in their frames, and leaks and openings in the air handler between the filter and blower. Even tiny gaps can reduce your filter’s effectiveness, so make sure your filter is the correct size for your air handler and is properly seated in the filter housing. You may need to seal up gaps that let air bypass the filter. (This is also a great opportunity to channel your inner Gandalf and yell “You shall not pass!” at the incoming air.  You know.  If you’re into that kind of thing.)

5.       Buy extra filters and be ready to change your filter mid-fire season.

Plan ahead and have extra filters on hand.  Better filters are great for improving air quality, but because they catch so much more material, they get dirty pretty fast. If we have a prolonged smoke event, there’s a decent chance you’ll need to change your filters after a couple weeks. Stock up now, and If we get lucky and dodge the bad smoke again this year, you’ll be ready to go for next year! 

6.       Close your windows and doors and seal up leaks to keep smoke outside.

You need to keep exterior doors and windows closed and seal up air leaks that let smoke sneak in.  A typical older home will let in about three times as much outdoor air through little air leaks compared to a new Energy Star home.

7.       Set your fan to “On” instead of “Auto.”

You will only receive cleaning benefits while the fan is running.  If you have your thermostat set to “Auto,” you’ll only see sporadic air cleaning.  Studies have shown that PACs with true HEPA filters are more effective at creating cleaner indoor air in a residential setting than central air systems, because PACs are more likely to be run continuously (unless they’re super loud. For more on that, see this blog post).  If you want to use your central air system to clean the air, you need to keep the fan on.  This will increase energy costs.  Happily, in Montana we don’t have year-round wildfire seasons.  Yay, winter!

8.       Keep interior doors open.

You’ll want to keep the interior doors open to avoid creating negative pressure in your main living space.  Your HVAC system likes balance – it pushes air into rooms and pulls air back into the air handler. If your return air vents aren’t getting air from the rooms with air supply vents, the HVAC system will pull air into your house to make up the difference.  This is super not helpful during a smoke event.  (Note that this scenario is more likely in older homes with a centrally located return vent.  Newer homes are more likely to have return vents in multiple rooms and halls.)  It’s a good idea to take a quick walking tour of your home to identify the air supply and return vents.  Your supply vents will have louvers and will blow cold air when your air conditioning is running.  Your return vents will likely be located near (or in) the floor, don’t have louvers and will not blow cold air.  To keep your system balanced, make sure your supply air will make it to a return vent.

9.       Find and replace all your filters

If you have multiple return vents, you may have multiple filters to replace.  The filters in HVAC systems are placed so that the return air is filtered before being sent into the air handler.  This keeps random contaminants, pet hair, bug parts, etc. from gumming up the works in your air handler.  If you aren’t sure where your filters are located, you can tour your HVAC system or ask your HVAC technician.  To help you get started, I googled “Where are the filters on my HVAC?” and found the following links helpful.  Got an HVAC question? Let me Google that for you!

(Note: a lot of these links go to company blogs.  This is not an endorsement of any single product.)

 

Here's a nice handout from Climate Smart Missoula that summarizes the previous 1800 words or so. 

Coming up next: things to know about air conditioners!  

July 17, 2020 

Make Your Own Air Cleaner! 

Do you want clean indoor air, but don’t want to shell out more cash than necessary? Do you have duct tape and a can-do attitude?

Then you, my friend, may be ready to make your own air cleaner.

Portable air cleaners are, at their heart, a filter and a fan. Sure, you can buy one with an attractive design on the casing or a remote control you’ll lose in three days. Some have pretty lights that tell you when the air is bad, and others rotate, because why not? But really, to clean the air, all you need is a filter and a fan.  Turns out, these technologies are readily available!

To build your own air cleaner, you need a newer box fan (we’ll get to why in a bit) and the highest efficiency 20”x20” furnace filter you can get your hands on. Ideally, you want a MERV 13 or better filter.  If you’re standing in the hardware store and your options are a 3M filter or a Honeywell, and you’re wondering where the heck they hide the MERV rating, I hear you. They make their own company-specific filter ratings.  It’s a thing.  I covered filter ratings in an earlier blog post: The Wonderful World of Filtration. The TL;DR: just get the highest efficiency one they offer (MPR 1500 or higher, FPS 10). If you read the filtration blog post, you are also familiar with the information that electrostatic furnace filters will be most effective at removing particles smaller than 0.3 microns in diameter for the first 2-3 weeks of use.  (Potentially less time, depending on how much smoke is in the air). The filters will continue to trap particles larger than 0.3 microns after they stop catching the super tiny ones.

When you get home from the store, attach the filter to the back of the fan so air flows through the filter before reaching the fan blades.  Some folks use zip ties for this, others enjoy generous amounts of tape. Some deploy bungee cords. It’s really a dealer’s choice. The point is, you want to cover as much of the back of the fan with the filter as possible, so air flows through the filter and not around it.  If you visit www.montanawildfiresmoke.org, there’s a video on the front page with Amy Cilimburg (executive director of Climate Smart Missoula) walking you through the DIY process.  While you’re there, check out the page dedicated to DIY fan/filter combos: https://www.montanawildfiresmoke.org/diy-fan-filter.html and download the handy 2-page guide.  

Boom.  You just made an air cleaner for under $45.

(If you’re feeling extra fancy and willing to spend more than $45, you can go for the two-filter triangle configuration described here: https://tombuildsstuff.blogspot.com/2013/06/better-box-fan-air-purifier.html.)

Let’s talk about the fan.  Some years ago, box fans had some run-ins with fire departments.  As in, the fans were overheating and starting fires.  This would, obviously, undermine a fan’s effectiveness as an air cleaner.  To prevent this from happening again, box fan manufacturers now include a kill switch (it’s really a fuse, not a switch) on their fans. Sometimes the fuse is in the plug, sometimes it’s in with the motor.  If the motor reaches a certain temperature, the fan dies, and it cannot be resuscitated without replacing the fuse. We reached out to local mechanical engineer, ASHRAE life member and all-around excellent human, Tom Javins, and asked him to try to make a fan overheat with a filter on it.  If you’ve ever met an engineer, you know this is the kind of challenge they live for. Reader, he tried. He blocked off both sides of the fan and ran it on high. He blocked the fan intake and laid it on carpet. He ran the fans under stress for days at a time.  He never came close to making the fans overheat.  Now, does this mean every fan everywhere is going to be safe? No. There are discrepancies in manufacturing, and DIY air cleaners require you to use a fan in a way that goes against the manufacturer’s recommendations.  We are not promising you a DIY air cleaner is safe. However, we are of the opinion that a new box fan will be safer than an old box fan, and it’s probably going to be ok. All the same, you probably should not leave one running unattended, and do not lie it on the carpet, block both sides of the fan or do any of the things that Tom did in his attempts to kill the box fans he was testing.  Keep it away from curtains or objects that may interfere with the fan, and make sure there’s room for good air flow around the machine. Make sure the fan stays clean as well - you don't want dust or flammable material gunking up the works in your fan. Use a clean filter and change it out when it gets dirty so air flows through the filter as easily as possible.

Now, let’s talk effectiveness.  Are DIY air cleaners effective at removing smoke? Yes. It can take a bit longer for a DIY setup with a MERV 13 filter to clean a room than a store-bought PAC with a true HEPA filter, but the air will improve over time.  A standard box fan and filter setup will be most effective in a room that’s 300 square feet or smaller.

Finally, let’s talk noise.  These setups are not silent. They are most effective with the fan running on high, which means there will be noise associated with the air cleaner.  But it also provides a nice cooling breeze, so it’s not all bad.  Remember, an air cleaner only works while it is turned on, so if you find yourself unable to tolerate a noisy fan, you may prefer a commercial portable air cleaner. (Note that some commercial PACs are also quite noisy.  You will want to do some due diligence and investigate noise levels before purchasing a PAC.)

Don’t forget to stock up on furnace filters. If we have a bad fire season, the filter on your air cleaner will fill up pretty quickly.  Once it’s noticeably quite dirty, you want to swap it out for a new filter.

As always, don’t forget to visit www.montanawildfiresmoke.org for information about how to prepare for the upcoming wildfire season. You can also visit my Smoke-Ready Blog and Resources site to catch up on previous posts and find links to some helpful information.


July 16, 2020 

Portable Air Cleaners

Are you tired of reading long-form blogs about cleaning the air? Would you rather sit back and watch me tell you about portable air cleaners? Then head on over to www.montanawildfiresmoke.org and check out HEPA Portable Air Cleaner video on the front page! This summer, I joined Amy Cilimburg (executive director of Climate Smart Missoula) and Tom Javins (mechanical engineer and ASHRAE life member) to record some socially distanced videos about creating cleaner indoor air spaces.  They are available at www.montanawildfiresmoke.org. As we prepare for wildfire season, I will be highlighting the videos that correspond with my blog posts. We will continue to create content this summer, but we already have some videos up for your viewing pleasure. And as always, that site has great tips for creating cleaner indoor air spaces as well as information about checking your local air quality, staying healthy during wildfire season, and understanding climate change science in Montana.

If you’re still in a reading mood, let’s get started! (And yes, if you’re an astute reader you’ll note this is last year’s post about portable air cleaners. The information is good and I am a huge fan of plagiarizing my own writing!)

To begin, if you’re going to get serious about having cleaner indoor air when wildfire smoke comes to town, you need to take steps to keep the smoke out in the first place. A well-sealed house will act as a barrier to slow smoke’s entry.  If you have leaky house, you can see so much outdoor air coming inside that you effectively have a small window open 24/7.  If you have a hard time keeping your house warm in the winter and deal with a lot of cold drafts, that’s a good sign you have a leaky house.  Sealing up your house will save energy and slow smoke’s entry during wildfire season.  Win, win!  Of course, eventually even a well-sealed house will see some smoke make its way inside, so it’s important to think of how you’re going to clean the indoor air. 

We’re going to kick that conversation off with portable air cleaners (PACs).  You may be more familiar with the term “air purifier.” While manufacturers advertise their machines as air purifiers, it’s more accurate to call them “air cleaners.”  You can’t really purify the air, but you can make it cleaner. Most government agencies and academics have adopted the terminology “portable air cleaner.” Not only is this a more accurate description of the machines, it also comes with a nifty acronym, that’s fun to use and say.  So, PACs it is! 

For the purposes of this blog, I’ll be focusing on PACs that clean the air using a true HEPA filter.  There are also PACs on the market that use electrostatic precipitation (ESP) or ionization to remove fine particulate matter from the air, but these technologies can produce ozone, which is terribly unhealthy to breathe.  Know what you don’t want from your air pollution-cleaning machine? Air pollution.  ESPs trap particles on plates that need to be cleaned and ionizers make the particulate drop from the air to stick to surfaces in your home.  There are several ESPs and ionizers on the market that produce low levels of ozone.  If you’re looking into one of these machines, check to make sure it’s on California’s list of Certified Air Cleaning Devices.  California will only certify PACs that produce ozone concentrations less than 0.050 parts per million, which is just below the national ambient air quality standard for ozone (0.070 parts per million). If you go the ESP route, make sure you clean the plates as needed to maintain effectiveness during wildfire season.

Alrighty.  Back to HEPA filter PACs. 

First off, what they do isn’t particularly complicated.  At its core, a HEPA PAC is a fan and a filter.  The fan pulls dirty air through the filter, the filter traps airborne particles and cleaner air exits the machine. Easy peasy. There are a lot of different styles of HEPA PACs on the market with various bells and whistles, but the fan and the filter are the primary components.  Note that while there are PACs that will clean a small bedroom in the $100 range, you can easily spend a lot more than that on a machine with more features and a larger cleaning area. 

HEPA PACs can be incredibly effective at removing particles from indoor air, but you need to do some due diligence and use them properly to see indoor air improvements. 

For HEPA PACs to be effective, they need to have a true HEPA filter, be sized appropriately for the room that they’re in, and they need to be turned on – ideally, all the way on.  You get the most cleaning benefit when you crank the fan all the way up.  This is where studies looking at PAC effectiveness run into the occasional example of less-than-stellar performance in the real world versus in the lab.  Some PACs make a lot of noise when turned on to their highest setting, and that’s when they get turned down or off by people tired of listening to the loud fan.  Turns out, turning a PAC off just kills its effectiveness. If you’re concerned about noise and have some extra dollars to throw around, consider purchasing a PAC sized for a larger room than the one you put it in – this way you should be able to still get a significant cleaning benefit at a speed other than “supersonic jet.”  Another option is to turn your PAC to its highest setting when you aren’t in the room you’re cleaning.  If your PAC is in your bedroom, turn it all the way up for a couple hours before hitting the sheets.  Provided your room’s doors and windows are closed and not terribly leaky, you should have decent air to start the night and be able to reduce the fan speed on the PAC to a more tolerable level. 

Now that you’ve figured out what noise level you’re ok with, you need to stock up on HEPA filters. If we have a bad wildfire smoke season, you’re probably going to want to change the HEPA filter in your PAC midway through the season.  I know most HEPA filters say they’re good for six months to a year, but that’s for normal air quality. Wildfire smoke is not normal air quality.  When filters become clogged with particulate, air can no longer pass through them.  You know how Jurassic Park taught us life will find a way?  Air will also find a way.  Once the air can no longer go through the filter, it will go around the filter.  You’ll likely still have air coming out of the machine, but it won’t be clean air.  When the Health Department got our PACs back from the Seeley Lake and Lolo schools following the 2017 fires, the used HEPA filters were black and the insides of the machines were coated with soot left by air sneaking around the clogged filters.  That was an extreme fire season, but it was instructive. Now we stock up on HEPA filters.  You should, too! 

If you choose to get a PAC, plan on keeping it in the room where you spend the most time.  For example, it’s a good idea to run a PAC in your bedroom while you sleep.  Also, keep windows and doors to the room with the PAC closed to allow the machine to recirculate the air through its filter multiple times an hour. 

Keep in mind that HEPA filters do not remove the volatile organic compounds (VOCs) in smoke.  VOCs give smoke that campfire smell we all know so well, and they can make you feel pretty crummy.  While we generally consider the fine particulate matter in smoke to be the greater public health threat, VOCs are nasty business.  They’re also harder to remove from the air.  Generally, PACs with robust filters or technology to cut down VOCs will be quite a bit more expensive than your basic HEPA PAC.  A lot of HEPA PACs come with thin activated carbon pre-filters that are advertised to remove VOCs, but again, that’s for background concentrations.  The levels of VOCs in wildfire smoke will quickly saturate a thin prefilter. 

Important questions to ask when you look at an air cleaner:

  1. Does this unit use a true HEPA filter?

There are “HEPA-like” filters on the market, which are not the same thing as true HEPA and won’t be as effective at removing the fine particulate in smoke.  Remember, the fine particulate in smoke is less than 1 micron in diameter!  You want a filter that will remove the smallest particles possible, and that’s a true HEPA

      2. How many square feet will it cover?

If you end up with an undersized air cleaner that is unable to recirculate the room’s air through its filter 2-3 times per hour, you likely won’t see significant indoor air quality improvements.

 Also, keep in mind that the effective cleaning area is based on a room with 8-foot ceilings.  Do you have a luxuriously tall or vaulted ceiling? Fancy! Also, you’ll need to get your hands on a bigger air cleaner.  The more air you need to push through the filter, the larger machine you’ll need to purchase.

 3. Does this unit produce ozone?

Some air cleaners produce ozone, which is a criteria pollutant and harmful to human health.  Check to make sure the unit you are interested in has been approved by the California Air Resources Board (CARB) here: https://ww2.arb.ca.gov/our-work/programs/air-cleaners-ozone-products/california-certified-air-cleaning-devices.  The CARB only approves units that do not produce harmful levels of ozone.

 Good questions to ask:

1. Is this unit Energy Star rated?

Using less energy is good for the planet and your wallet!

2. Is it noisy?

A PAC is only effective if it’s turned on, and it’s most effective if it’s turned all the way up. If you’re sensitive to noise, you’ll want to look for quieter models.  No matter what, expect some level of noise when you turn your PAC all the way up.  Fans can push a lot of air, and that will tend to generate noise.

 

3. How expensive are replacement filters?

Do some legwork and find out how much the manufacturer charges for replacement filters.  You may also want to investigate filters offered by third parties. There are several companies making HEPA filters that will fit popular PAC models, and they often cost less than manufacturers’ filters.  Keep in mind, using third party filters may void the PAC’s warranty. 

Valuable question to ask:

  1. How effective is the unit at removing volatile organic compounds (VOCs)?

There are multiple methods for removing VOCs, but the most common one you’ll see is an activated carbon prefilter.  While activated carbon can remove VOCs, be aware that it can get saturated pretty quickly, which limits the effectiveness of a lot of the carbon prefilters on the market.  If you are concerned about the VOCs in smoke, you can plan on changing the prefilter out frequently or you can invest in an air cleaner with a robust activated carbon filter.  Note that the hefty activated carbon filters can be quite pricey.  Typically, the more fancy the VOC removal, the more expensive the machine (and the replacement filters).  For some folks, though, removing VOCs will be worth the price.

If you’re still in a reading mood and want some in-depth information, check out EPA’s document: “Residential Air Cleaners: A Technical Summary”: https://www.epa.gov/sites/production/files/2018-07/documents/residential_air_cleaners_-_a_technical_summary_3rd_edition.pdf. There is a lot great information about PACs as well as some detail about using your home HVAC to create cleaner indoor air, which I will be covering in a future post. Spoilers!

 That’s it on store-bought PACs for now.  Coming up in the next blog: making your own PAC!


July 13, 2020

The Wonderful World of Filtration 

As COVID-19 cases grow and our communities strive to keep buildings open to employees and the public, there’s a lot of talk about lowering COVID-19 risk indoors.  If you pop on over to the CDC’s ever-growing COVID-19 guidance pages, you’ll find long lists of recommendations. Here’s what it boils down to: Bring in as much outdoor air as possible. Fling those windows open, put fans in the windows to pull the outside air in, turn the fresh air intake on your heating, ventilation and air conditioning system (HVAC) all the way up, and flood the indoors with the sweet, sweet summer air.

Meanwhile, during wildfire smoke events, best practices to protect building occupants revolve largely around keeping outdoor air outside: Close doors and windows, turn off the outdoor air intake as much as possible while keeping CO2 levels safe, and stew in your recycled air.

To quote Sesame Street: “One of these things is not like the other.”

Fresh air is usually good for you and bringing in lots of outdoor air to dilute possible virus concentrations makes a lot of sense.  The trouble is, during wildfire season, the outdoor air itself can become dangerous.  The CDC recognizes this and includes the caveat that if the outdoor air is harmful to the building’s occupants, do not throw open all the windows or set your HVAC system to 100% fresh air intake.

So now what?

An article in the May 2020 ASHRAE Journal recommends improving central air filtration and using HEPA portable air cleaners to protect building occupants from Covid-19.  Frequent readers of this blog may recognize this as the same recommendation we provide for wildfire smoke. Hot dippity dog! An overlap!

An important caveat: we know filters will help reduce wildfire smoke particulate concentrations.  Filters’ ability to create safer indoor air from the virus that causes COVID-19 is mostly theoretical at this time. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has a long list of recommendations and considerations for HVAC systems and COVID-19 here: https://www.ashrae.org/technical-resources/filtration-disinfection#mechanical

Anyway. Today, we’re going to focus on things you should know about filters.  We’ll get into portable air cleaners and HVAC systems and all of that goodness in a future post or two, but let’s start with the thing that’s actually capturing pollutants.

The particles in wildfire smoke are incredibly small.  Just tiny. When we report fine particulate pollution, we call it PM2.5, which is particulate matter 2.5 microns in diameter and smaller.  The particles in wildfire smoke are much smaller than even 1 micron in diameter.  Imagine taking a grain fine of beach sand, say 1 millimeter in diameter. Cut it in half. Cut in half again. And again. Keep cutting it in half until you are left with a grain of sand that is 10,000 times smaller than the size you started with. This, my friends, is an ultrafine particle and it will mess you up. (Fun fact: ultrafine particles are similar in size to the virus.)

These tiny particles are, as you can imagine, hard to catch. You know how you don’t use a colander to filter bacteria and viruses out of your water? It’s not just because colanders make goofy hats and added weight while backpacking. It’s because you need the proper filter to remove pathogens from your water.  You also need the proper filter to remove particulate from your air. 

Air filter efficiency is described on the MERV scale. MERV stands for Minimum Efficiency Reporting Value.  It was developed by ASHRAE to evaluate air filters.  The MERV ratings classify a filter’s ability to capture different sizes and amounts of particles at each pass.  For example, a MERV 3 will effectively filter large particles, such as cat hair and the bits and pieces of insects that end up in HVAC systems.  No one wants to inhale bug parts, but these are not the particles we’re concerned about during wildfire season. With each pass, a low-rated MERV (1-4) will filter less than 20% of coarse particles that are 3-10 microns in diameter (like road dust) and won’t do anything to stop the fine particulate in smoke.  A MERV 13, meanwhile, will remove about 90% of all particles larger than 1 micron in diameter and will remove about 50% of fine particles 0.3-1 micron in diameter with each pass.  MERV 17-20 gets into High Efficiency Particulate Air (HEPA) range, with greater than 99.9% of all particles 0.3 microns and larger being removed with each pass.  High MERV ratings (15+) are typically found in hospital and surgery settings. If you’re craving more numbers and details, here’s a link to a handy dandy chart: http://www.mechreps.com/PDF/Merv_Rating_Chart.pdf. If you’d like to know more about MERV and how filters are tested, here’s a useful (if somewhat technical) article from the National Air Filtration Association, helpfully titled “Understanding MERV” : https://www.nafahq.org/understanding-merv-nafa-users-guide-to-ansi-ashrae-52-2/.

Generally speaking, if you want to use a filter to remove the fine particulate matter in smoke, you want to aim for a MERV 13 or better filter.

The good news is, a lot of stores sell MERV 13 filters.  The bad news is, it can be hard to find the MERV rating on consumer-grade filters.  Both 3M and Home Depot have created their own scales to describe their filters’ efficacy (MPR filters and FPR, respectively), and they don’t correspond perfectly with MERV ratings.  This is, for the savvy filter consumer, horribly unhelpful; it makes it difficult to compare filtration across brands.  The MERV scale is the official metric used to measure filters’ effectiveness, and even though these brands display their own scales to customers on their packaging, everything comes back to MERV.  If you want to take a deeper dive, this (dare I say sassy?) blog post from a filter delivery company delves into MERV, MPR and FPR: http://blog.filtersnap.com/merv-vs-mpr-vs-fpr-the-definitive-guide/.

I have had some success finding the MERV ratings by examining the fine print around the edges of filters.  In general, the best consumer grade filters sold by 3M (MPR 1500+) and Home Depot (FPR 10) will be MERV 13s. 

When researching MERV 13 furnace filters on your own (everyone does this, right?), you may have come across references to electrostatic filters. In addition to capturing particles 0.3 microns in diameter and larger, electrostatic filters will capture fine and ultrafine particles that are smaller than 0.3 microns, but their time window for doing so is limited. I asked Tom Javins, a local mechanical engineer, ASHRAE Life Member and all-around excellent human for insight into electrostatic filters and their efficacy at capturing different particle sizes.

Here’s what he said:

“Electrostatic media is a more open filtration material that has a lower pressured drop than an equivalent mechanical filter. This means you can use a more efficient filter and still get similar airflow characteristics from a furnace fan. There are both positive and negative charges on the surface of the polyester media. As they attract and hold small particles, that charge is no longer available. You could call that saturation of the electrostatic forces. The electrostatic filter then becomes a mechanical filter that will not capture the very small particles.

In talking to filter testing lab engineers, the <0.3 micron capture by electrostatic filters is best when new, and depletes in a few weeks. This size is below the lowest commonly tested particle size range. The 0.3 to 1 micron capture (E1 fraction of the ASHRAE 52.2 test) continues for about 90 days for electrostatic media, after that they effectively become mechanical filters.

As mechanical filters load with dirt, the dirt forms dendritic structures that improve the capture of small particles. That is why the rating system uses the minimum reported efficiency value (MERV).”

Thanks, Tom!

As Tom indicated, the tests used for determining MERV do not look at capture efficiency below 0.3 microns.  However, particles come smaller than 0.3 microns, and the smaller the particle, the worse it is, so it wouldn’t hurt to take advantage of the electrostatic action on better furnace filters. Just know that after a few weeks (or less, depending on the smoke levels), the filters will cease capturing particles smaller than 0.3 microns.

Now, what about HEPA filters? If you are using portable air cleaners with true HEPA filters, you have a good shot at catching fine and ultrafine particles smaller than 0.3 microns in diameter. HEPA filters do not rely on electrostatic attraction to capture fine and ultrafine particles.  Instead, they capture particles via inertial impaction, interception and Brownian diffusion. This 2016 paper by NASA provides a good explanation of how HEPA filters work, as well as nifty diagrams.  I recommend checking the paper out if you want to know more about HEPA filters. Here’s my top pull quote about HEPA filters’ ability to remove particles from the air:

“The diffusion regime is dominant in the range of the smallest particle diameters, submicron and below. A very high proportion of the particles in this size range, up to 100% at the very smallest particle sizes, get captured by the fibers throughout the media. In the upper particle size range, the supermicron range, inertial impaction, and interception are the key capture mechanisms. This regime is also characterized by a very high percentage of particle capture, particularly at the largest particle sizes. In the intersecting regime between these two particle size ranges, the effects of the particle diffusion are shown to taper off while the effects of inertial impaction and interception start to dominate. . . The key implication to emphasize is that HEPA filters are nearly 100% efficient at capturing the spectrum of particles down to the very smallest airborne particles.” (emphasis added)

Also, if your eyes glazed over, this is why science writers have jobs.

Here’s the take-home: air filters can capture dangerous particles, but their efficiency will vary. The higher the MERV rating on your filter, the more effective it should be at capturing smaller particles.  HEPA filters (which you find in portable air cleaners) will be the most effective at capturing the smallest particles in wildfire smoke. 

In a future posts we’ll talk about how to use your portable air cleaners or central air handlers to best take advantage of higher efficiency filters.  There are some important best practices to follow and some precautions to know about before using your central air handler to clean wildfire smoke out of your air space.

As always, if you don’t want to wait for my next post, you can hop over to Climate Smart Missoula’s website www.montanawildfiresmoke.org or visit the Missoula County Smoke-Ready Resources and Blog for tips on creating cleaner indoor.


July 6, 2020 

Smoke Ready Blog: An annual summer tradition

Migrating songbirds are caring for their fledged chicks, waves of pollen are drifting on the breeze, and huckleberries are ripening in the mountains. It’s summer. And in a great summer tradition, your local air quality specialists are looking at fire danger projections and fussing. 

Remember 2019? I know anything from the before-time feels hazy, but 2019 was remarkable for its distinct lack of haze.  We didn’t really have any wildfire smoke.  It was cool and wet and the air was fantastically breathable.  This year is looking to be decidedly worse, which is very 2020 of it.

The predictive meteorologists with the Northern Rockies Coordination Center are expecting above average fire activity for our region in August and September.  The crazy amount of rain we received last week bought us a predicted “normal” July. However, things are heating up out there, and July will be over sooner than any of us would like. 

So, as we prep for a potentially bad fire season, and therefore bad smoke season, I have a question: Do you know where your air filters are?

Hopefully, last year you stocked up on efficient furnace filters for your HVAC or HEPA filters for your portable air cleaners, and you’re ready for this year.  If not, the time to prepare for wildfire smoke is now, my friends.  Remember when you couldn’t find toilet paper on the shelves? Nobody wants a toilet paper moment with air filters. Don’t wait for the smoke to arrive to restock!

Now, some of you may be new to the idea of becoming a wildfire smoke prepper.  That’s ok.  I’m here to help.  We prepare for wildfire smoke because it is a dangerous pollutant.  Smoke is a veritable chemical stew, but the component we’re most concerned about is fine particulate matter, which in smoke is less than 1 micron in diameter.  The fine particulate is so tiny it bypasses your natural defenses when you breathe it in and can pass into your bloodstream where it sets off an inflammatory response.  Its health impacts include (but are not limited to) exacerbated asthma, reduced lung function, worsened COPD symptoms, increased risk of heart attack and stroke, increased hospitalizations and mortality.  Children, the elderly, people with diabetes, people with heart or lung disease and pregnant people are most at risk.  This translates to roughly 30 percent of a given population.  And, even if you aren’t in the “at-risk” category, the smoke is bad for you, and the longer you’re in it the worse it is.  We haven’t even touched on the complicating factor of Covid-19. Which, unsurprisingly, is bad.

The best way to avoid smoke is to have clean air to breathe.  Unfortunately, smoke is quite good at coming indoors, which means in order to have cleaner air to breathe, you need to take some proactive steps to make it cleaner.  Hence, the prepping.

Over the next several days (possibly weeks), I will provide you with information on creating cleaner air spaces in your homes.  We’ll go over furnace filters, portable air cleaners, and what to do when it’s hot and smoky outside.  We’ll also discuss larger spaces such as office buildings, schools, gyms, etc. and steps they can take to protect their occupants from smoke.

Along the way, we’ll discuss the intersection of Covid-19 and wildfire season, and how it will impact how we navigate smoke season.  For now, understand that in the era of covid, creating cleaner indoor air is more important than it has ever been. Many of the at-risk categories for Covid-19 and wildfire smoke overlap. To make matters worse, a recent study found exposure to air pollution led to worse health outcomes for covid patients.  There is far more pollution in a wildfire smoke plume than any background air pollution in the U.S. If we want to avoid the compounding impact of wildfire smoke on Covid-19, we need to have clean air to breathe.

If you’re excited to learn more about creating cleaner indoor air and don’t want to wait for my next post, you can hop over to Climate Smart Missoula’s website www.montanawildfiresmoke.org or stay here on the Missoula County Smoke-Ready Resources and Blog, which I will be adding to over the coming days and weeks.  The information on how to create cleaner indoor air hasn’t changed much over the last few years, so you will be well-served by checking out last year’s smoke-ready blog on this site or by checking out any of the great tips, advice, videos and infographics on Climate Smart Missoula’s site. (Climate Smart Missoula is also working on some great new content for that site, so keep checking back!)

For now, get outside if you can!  Enjoy the warm weather and clean air.  The grass is still green(ish), the wild strawberries are ripening, and you can still find wildflowers on the hills. And while you bask in the glorious Montana July, make a plan for protecting your family from wildfire smoke.


July 23, 2019

Coping with smoke and heat

Full disclosure: Savvy smoke-ready blog readers will realize I basically used this same post last year. That’s what we call efficiency!

Did you go outside today?  The temperature actually hit 90 degrees.  It’s been a pretty cool summer, but we’re finally seeing some seasonal temperatures.  And while the summer hasn’t been a scorcher, I already installed my window air conditioner (my cat is old and ever-so-fluffy, and I fuss about leaving her to her own devices in the hottest part of the day. Hyper-vigilant pet parents unite!).

Anyway.

We’re likely to continue to see temperatures bouncing up to 90 or hovering in the mid-80s for a while. Even if you don’t have a geriatric fluff ball at home, that means it’s time to talk about air conditioning.  And smoke!  There’s always a way to work smoke into a conversation.  This is why air quality specialists make terrific (or terrible) dinner guests. 

With the potential for some seasonal temperatures and the likely return of wildfire smoke in the coming weeks, it’s important to make plans for keeping your house cool.  According to the Centers for Disease Control, every year more than 600 people in the United States are killed by extreme heat.  However, heat-related illnesses are preventable, and one of the steps you can take is cooling your home. 

I would be remiss in my air specialist duties if I didn’t remind ya’ll that air conditioners can be energy hogs, which is a no-no when we’re trying to confront climate change by reducing energy use.  However, your health is crazy important, so I’m not going to tell you not to use it.  Do try to limit your air conditioner use to the amount needed to keep your house at a safe temperature and as smoke-free as possible.  Climate Smart Missoula has some nifty tips for keeping your home cool(ish) in the summer: https://www.missoulaclimate.org/hotter-days-and-nights.html 

Do you have central air conditioning? Awesome!  If possible, bypass the fresh air intake when smoke arrives, upgrade your system’s filter (see last week’s blog post), keep your doors and windows closed, and enjoy the cool, clean air.  Also, maybe invite some friends or relatives over to share in your bounty. 

A lot of us do not have central air conditioning.  That leaves us with window air conditioners, portable air conditioners (those rolling things with giant hoses that send exhaust out the window), and the good old-fashioned method of opening windows at night and using fans to push hot air out and draw cool air in. Whichever method you use is personal preference, but the tricky thing here is smoke infiltration.  Opening windows at night works pretty well when it’s not smoky.  Unfortunately, the nice cool air that is so refreshing at night is the same cool air that traps smoke near the valley floor.  It’s not uncommon for us to see thick overnight smoke, and that smoke will move right into your home when you open your windows.  If you have no other option, it may be best to open your windows for long enough to cool your home, and then, once you’ve closed the windows, crank up your portable air cleaner(s) (PACs) to remove the smoke.  It is very important to avoid heat stress.  It can feel like a lousy bargain – clean air or cool air, but if you have an appropriately sized PAC with HEPA filtration on hand, you should be able to clean the smoke out of a room relatively quickly. 

And now, a brief foray into window and portable air conditioners.  First, we need to talk very briefly about how air conditioners work.  Disclosure: I am not an air conditioning expert.  I don’t even play one on T.V.  I have, however, honed my googling skills.  After much trial and very little error, I recommend the search queries “How do window air conditioners work?” and “How do portable air conditioners work?” Don’t let anyone tell you we aren’t a full-service health department.

Moving on.

Air conditioners transfer heat from your inside air to the outside air in a process that involves a cool air cycle and a hot air cycle. In the cool air cycle, the air conditioner draws indoor air across cooling coils, transferring the heat from the air to the refrigerant in the coils.  The now-cooled air is released back into the room.  The heated refrigerant needs to be cooled down, so in a separate part of the machine, the air conditioner pulls outside air across the heated refrigerant.  The heat from the refrigerant transfers to the air and the machine sends the now extra-warm air back outside.  A properly installed window air conditioner should keep these two air cycles separate.  Inside air cycles across the cooling coils and is released back inside and outside air cycles across the heated refrigerant and is released back outside.

Here’s a nifty link to a site that describes the process in better detail: https://homeairguides.com/air-cooling/how-does-a-window-air-conditioner-work/

Here’s a snazzy diagram for those of us who like our air conditioner explanations in picture form: https://commons.wikimedia.org/wiki/File:Air_conditioning_unit-en.svg

Because window ACs recirculate room air, they generally keep indoor air in and outside air out.  However, some models have a feature that allows the user to bring in fresh air.  Check your model for a fresh air intake and be certain to close it during a smoke event.  Also, you will want to make sure the area around your window AC is as sealed as possible to limit smoke infiltration around the sides of the machine.  Once the area around the AC is sealed, peer into your window AC through the room-facing vents.  Can you see sunlight? Some ACs have Styrofoam dividers on their insides, and the seams aren’t perfectly sealed.  These small cracks let in sunlight and are also likely to let in some smoke. Also, if you have a jerry-rigged setup such as a window AC unit in a side-sliding window, you may need to basically treat your window AC unit as an open window.  In general, it’s probably a good idea to keep an appropriately sized PAC running in whichever room has a window AC.

If you want to use your window air conditioner to help filter your indoor air, research your machine’s ability to function with an upgraded air filter.  Window air conditioners have filters, but they’re designed for catching dust and pet hair, not the fine particulate in smoke.  There are some aftermarket window air conditioner filters out there, but they can be a bit dodgy on specifics about particulate removal.  Also, you need to cautious about adding an upgraded filter to a window air conditioner because the increased resistance can put significant stress on the machine. If you choose to upgrade your filter, get the highest MERV-rated filter you can for your model of window air conditioner, and use your PAC with HEPA filtration to clean whatever is left over.

Because of their design, portable air conditioners can be used with more window types than a window air conditioner, so they may be an option worth considering if you have side-sliding windows.  However, they tend to be considerably more expensive than window air conditioners and not all portable air conditioners are created equal.  Portable air conditioners come in two types: single and dual hosed.  In both types, the hoses bring in outdoor air to cool the refrigerant and send heated exhaust out the window. A single-hosed portable unit will use the same hose for both intake and outtake.  Because it can’t draw in enough outdoor air to cool its refrigerant, the single-hosed unit will also draw in your nice cool room air to cool itself down and send that air out the window.  This could be problematic during fire season, because the process creates negative pressure in your home.  The negative pressure will pull outside air into your house through various nooks and crannies, and if it’s smoky outside, it may also pull smoke into your home.  Dual-hosed portable ACs avoid the negative pressure issue by having a hose dedicated to drawing outside air into the machine to cool the coils.  This way, only outside air is exhausted out the window – inside air stays inside and the pressure in your house should remain stable.  However, dual-hosed portable air conditioners tend to be quite a bit more expensive than single-hosed machines.  If you are using a portable air conditioner, try to seal the edges where the exhaust plate meets your window as much as you can.  Otherwise, there’s a good chance smoke will sneak in around the edges.   Use your PAC to clean out whatever smoke ends up inside.  This will be particularly important if you have a single-hosed portable AC. 

The take home message is this: You need to be able to cool your home, and there’s a good chance the process of cooling your home will introduce smoke into your breathing space.  If you have a PAC with true HEPA filtration you can reduce the amount of smoke that stays in your home.  In 2017, Climate Smart Missoula ran particulate sensors in a house that did not have air conditioning but did have PACs with HEPA filtration.  Yes, smoke came into the house overnight when smoke rolled into town.  However, within a couple hours of closing the windows and turning on the air cleaners, that house had some of the best air in Missoula. 

If you don’t have air conditioning and, based on your health, you can’t allow any smoke into your home, your best option may be to find somewhere else to be next time smoke rolls into town.  You may need to stay somewhere local with air conditioning and filtered air or leave the valley to find clean air. 

Stay cool and breathe safe!

 


 

July 18, 2019

Using your HVAC system to clean your indoor air

In my last update I wrote about using portable air cleaners (PACs) to create cleaner indoor air during smoke events.  Typically, folks will use PACs to clean individual rooms.  For those who want to have cleaner air throughout their entire house, they will either need to purchase multiple PACs or use their central air handler or furnace fan to push air through a filter and distribute the air throughout their home.

(If you decide to go the PAC route, know that a PAC isn’t going to move air throughout the house.  If you place a PAC in the living room, it’s not going to do a great job cleaning the air in the bedrooms down the hall even if the PAC is rated for a really large space and the doors are left open.  Air just doesn’t corner very well.)

Now, before we get into this, here is my disclaimer: I am not an HVAC technician.  I’ve spoken with some folks who know things and I’ve done a lot of reading, but this does not make me an expert. If you have questions about your specific air handler/furnace/air conditioner, etc., please talk to your HVAC technician.

Alrighty.  Let’s go.

It’s becoming more common these days for homes to be built with HVAC systems (heating, ventilation and air conditioning) that use central air handlers for cooling and/or heating. In addition to impressing the socks off this Montana child of the ‘80s (Air conditioning in a house???  That’s some fancy stuff right there!), the filters on air handlers can be handy tools for cleaning indoor air throughout your home during a smoke event.  Your duct work will deliver air to each room, which solves the cornering problem PACs face.

Note that If you have central air for heat, but not air conditioning, you can still clean your indoor air by turning your furnace fan on without the heat.

To get started, we need to dig into HVAC filters.  First, find where your filter(s) are housed in your HVAC system (note that some homes may have more than one air return and corresponding filter). Look at your filter.  Is it a flat panel? Is it washable?  Is it something you’d take outside, hose off and return to its casing? If so, and if want to use your HVAC to clean your air, you need a different filter.  A better HVAC filter will have a whole bunch of fabric pleats and cannot be washed.  Note that even if you have a filter with some pleats and you wouldn’t dream of washing it with a hose, there’s a good chance the filter currently sitting in your air handler is not going to remove fine particulate matter from smoky air.  Homes will generally have a filter that is MERV 6 or less, and you need to upgrade to at least a MERV 13 to get a filter that has been tested and shown to remove the tiny particles in wildfire smoke. 

What’s a MERV, you ask? Well, gather round and let me tell you more than you ever knew you wanted to know about filters!

MERV stands for Minimum Efficiency Reporting Value.  It was developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to evaluate air filters.  The MERV ratings classify a filter’s ability to capture different sizes and amounts of particles at each pass.  For example, a MERV 3 will effectively filter large particles, such as cat hair and the bits and pieces of insects that end up in HVAC systems.  No one wants to inhale bug parts, but these are not the particles we’re concerned about during wildfire season. With each pass, a low-rated MERV (1-4) will filter less than 20% of coarse particles that are 3-10 microns in diameter (like road dust) and won’t do anything to stop the fine particulate in smoke.  A MERV 13, meanwhile, will remove about 90% of all particles larger than 1 micron in diameter and will remove about 50% of fine particles 0.3-1 micron in diameter with each pass.  MERV 17-20 gets into HEPA range, with greater than 99.9% of all particles 0.3 microns and larger being removed with each pass.  High MERV ratings (15+) are typically found in hospital and surgery settings. If you’re craving more numbers and details, here’s a link to a handy dandy chart: http://www.mechreps.com/PDF/Merv_Rating_Chart.pdf. If you’d like to know more about MERV and how filters are tested, here’s a useful (if somewhat technical) article from the National Air Filtration Association, helpfully titled “Understanding MERV” : https://www.nafahq.org/understanding-merv/.

The good news is, a lot of stores sell MERV 13 filters.  The bad news is, it can be hard to find the MERV rating on consumer-grade filters.  Both 3M and Home Depot have created their own scales to describe their filters’ efficacy (MPR filters and FPR, respectively), and they don’t correspond perfectly with MERV ratings.  This is, for the savvy filter consumer, horribly unhelpful; it makes it difficult to compare filtration across brands.  The MERV scale is the official metric used to measure filters’ effectiveness, and even though these brands display their own scales to customers on their packaging, everything comes back to MERV.  If you want to take a deeper dive, this (dare I say sassy?) blog post from a filter delivery company delves into MERV, MPR and FPR: http://blog.filtersnap.com/merv-vs-mpr-vs-fpr-the-definitive-guide/.

I have had some success finding the MERV ratings by examining the fine print around the edges of filters.  In general, the best consumer grade filters sold by 3M (MPR 1500+) and Home Depot (FPR 10) will be MERV 13s.

Before you start using your central air system to clean your indoor air, there are some things you need to know and steps you need to take:

1.       Can your HVAC system handle a better filter?

Not all furnaces or air handles can deal with the added resistance from better filters.  The better the filter, the harder it is to pull air through it. Folks in the HVAC world call this the “pressure drop.” As you increase MERV, you also increase pressure drop.  If you aren’t sure if your HVAC can handle a better filter, talk to your HVAC technician.

2.       Thicker filters are better (but also more expensive).

Thick pleated filters (4 to 5 inches deep), will allow greater airflow through your air handler than 1-inch pleated filters.  This will reduce the energy required to pull air through the filter and will help with concerns about pressure drop.  Not all air handlers will have slots for these thicker filters, but if you can, aim for a thicker filter.

3.       Install your filter correctly.

There is an arrow on your filter.  It needs to point in the same direction as the airflow.

4.       Can air sneak around your filter? That’s a no-no!

Once you’ve slid the new filter into its slot, take a good, hard look at it.  Is it loose? Can air easily bypass the filter?  If air can move around the filter instead of through the filter, you won’t get much benefit from your fancy new filter.  You’ve basically put up pretty curtains but forgot to close the window.  Filter bypass is often caused by poorly fitting filters, poor sealing of filters in their frames, and leaks and openings in the air handler between the filter and blower. Even tiny gaps can reduce your filter’s effectiveness, so make sure your filter is the correct size for your air handler and is properly seated in the filter housing. You may need to seal up gaps that let air bypass the filter. (This is also a great opportunity to channel your inner Gandalf and yell “You shall not pass!” at the incoming air.  You know.  If you’re into that kind of thing.)

5.       Buy extra filters and be ready to change your filter mid-fire season.

Plan ahead and have extra filters on hand.  Better filters are great for improving air quality, but because they catch so much more material, they get dirty pretty fast. If we have a prolonged smoke event, there’s a decent chance you’ll need to change your filters after a couple weeks. Stock up now, and If we get lucky and dodge the bad smoke again this year, you’ll be ready to go for next year! 

6.       Close your windows and doors and seal up leaks to keep smoke outside.

You need to keep exterior doors and windows closed and seal up air leaks that let smoke sneak in.  A typical older home will let in about three times as much outdoor air through little air leaks compared to a new Energy Star home.

7.       Set your fan to “On” instead of “Auto.”

You will only receive cleaning benefits while the fan is running.  If you have your thermostat set to “Auto,” you’ll only see sporadic air cleaning.  Studies have shown that PACs with true HEPA filters are more effective at creating cleaner indoor air in a residential setting than central air systems, because PACs are more likely to be run continuously (unless they’re super loud. For more on that, see the previous blog post).  If you want to use your central air system to clean the air, you need to keep the fan on.  This will increase energy costs.  Happily, in Montana we don’t have year-round wildfire seasons.  Yay, winter!

8.       Keep interior doors open.

You’ll want to keep the interior doors open to avoid creating negative pressure in your main living space.  Your HVAC system likes balance – it pushes air into rooms and pulls air back into the air handler. If your return air vents aren’t getting air from the rooms with air supply vents, the HVAC system will pull air into your house to make up the difference.  This is super not helpful during a smoke event.  (Note that this scenario is more likely in older homes with a centrally located return vent.  Newer homes are more likely to have return vents in multiple rooms and halls.)  It’s a good idea to take a quick walking tour of your home to identify the air supply and return vents.  Your supply vents will have louvers and will blow cold air when your air conditioning is running.  Your return vents will likely be located near (or in) the floor, don’t have louvers and will not blow cold air.  To keep your system balanced, make sure your supply air will make it to a return vent.

9.       Find and replace all your filters

If you have multiple return vents, you may have multiple filters to replace.  The filters in HVAC systems are placed so that the return air is filtered before being sent into the air handler.  This keeps random contaminants, pet hair, bug parts, etc. from gumming up the works in your air handler.  If you aren’t sure where your filters are located, you can tour your HVAC system or ask your HVAC technician.  To help you get started, I googled “Where are the filters on my HVAC?” and found the following links helpful.  Got an HVAC question? Let me Google that for you!

(Note: a lot of these links go to company blogs.  This is not an endorsement of any single product.)

 

Here's a nice handout from Climate Smart Missoula that summarizes the previous 1800 words or so. 

Coming up next week: things to know about air conditioners!  Just in time for the coming heatwave.  Holy cats, it’s about to get hot.


 

July 9, 2019 

Creating cleaner indoor air with portable air cleaners

Did Sunday’s sunset look a little too pink to you? Did it make you stop and say, “Hmmmm,” and then maybe start obsessively looking at heat detection maps and satellite photos to figure out where the smoke was coming from?  Then congratulations! You, too, could be an air quality specialist! 

Anyway. 

There’s some high-level haziness in the air from far away wildfires.  It hasn’t impacted our air quality, but it’s a good reminder that even though so far, we’re having a cool, wet summer, other areas are already on fire. (Looking at you, Alaska.) 

It’s also a good reminder to start preparing now for wildfire smoke season! 

To begin, if you’re going to get serious about having cleaner indoor air when wildfire smoke comes to town, you need to take steps to keep the smoke out in the first place. A well-sealed house will act as a barrier to slow smoke’s entry.  If you have leaky house, you can see so much outdoor air coming inside that you effectively have a small window open 24/7.  If you have a hard time keeping your house warm in the winter and deal with a lot of cold drafts, that’s a good sign you have a leaky house.  Sealing up your house will save energy and slow smoke’s entry during wildfire season.  Win, win!  Of course, eventually even a well-sealed house will see some smoke make its way inside, so it’s important to think of how you’re going to clean the indoor air. 

We’re going to kick that conversation off with portable air cleaners (PACs).  You may be more familiar with the term “air purifier.” While manufacturers advertise their machines as air purifiers, it’s more accurate to call them “air cleaners.”  You can’t really purify the air, but you can make it cleaner. Most government agencies and academics have adopted the terminology “portable air cleaner.” Not only is this a more accurate description of the machines, it also comes with a nifty acronym, that’s fun to use and say.  So, PACs it is! 

For the purposes of this blog, I’ll be focusing on PACs that clean the air using a true HEPA filter.  There are also PACs on the market that use electrostatic precipitation (ESP) or ionization to remove fine particulate matter from the air, but these technologies can produce ozone, which is terribly unhealthy to breathe.  Know what you don’t want from your air pollution-cleaning machine? Air pollution.  ESPs trap particles on plates that need to be cleaned and ionizers make the particulate drop from the air to stick to surfaces in your home.  There are several ESPs and ionizers on the market that produce low levels of ozone.  If you’re looking into one of these machines, check to make sure it’s on California’s list of Certified Air Cleaning Devices.  California will only certify PACs that produce ozone concentrations less than 0.050 parts per million, which is just below the national ambient air quality standard for ozone (0.070 parts per million). 

Alrighty.  Back to HEPA filter PACs. 

First off, what they do isn’t particularly complicated.  At its core, a HEPA PAC is a fan and a filter.  The fan pulls dirty air through the filter, the filter traps airborne particles and cleaner air exits the machine. Easy peasy. There are a lot of different styles of HEPA PACs on the market with various bells and whistles, but the fan and the filter are the primary components.  Note that while there are PACs that will clean a small bedroom in the $100 range, you can easily spend a lot more than that on a machine with more features and a larger cleaning area. 

HEPA PACs can be incredibly effective at removing particles from indoor air, but you need to do some due diligence and use them properly to see indoor air improvements. 

For HEPA PACs to be effective, they need to have a true HEPA filter, be sized appropriately for the room that they’re in, and they need to be turned on – ideally, all the way on.  You get the most cleaning benefit when you crank the fan all the way up.  This is where studies looking at PAC effectiveness run into the occasional example of less-than-stellar performance in the real world versus in the lab.  Some PACs make a lot of noise when turned on to their highest setting, and that’s when they get turned down or off by people tired of listening to the loud fan.  Turns out, turning a PAC off just kills its effectiveness. If you’re concerned about noise and have some extra dollars to throw around, consider purchasing a PAC sized for a larger room than the one you put it in – this way you should be able to still get a significant cleaning benefit at a speed other than “supersonic jet.”  Another option is to turn your PAC to its highest setting when you aren’t in the room you’re cleaning.  If your PAC is in your bedroom, turn it all the way up for a couple hours before hitting the sheets.  Provided your room’s doors and windows are closed and not terribly leaky, you should have decent air to start the night and be able to reduce the fan speed on the PAC to a more tolerable level. 

Now that you’ve figured out what noise level you’re ok with, you need to stock up on HEPA filters. If we have a bad wildfire smoke season, you’re probably going to want to change the HEPA filter in your PAC midway through the season.  I know most HEPA filters say they’re good for six months to a year, but that’s for normal air quality. Wildfire smoke is not normal air quality.  When filters become clogged with particulate, air can no longer pass through them.  You know how Jurassic Park taught us life will find a way?  Air will also find a way.  Once the air can no longer go through the filter, it will go around the filter.  You’ll likely still have air coming out of the machine, but it won’t be clean air.  When the Health Department got our PACs back from the Seeley Lake and Lolo schools following the 2017 fires, the used HEPA filters were black and the insides of the machines were coated with soot left by air sneaking around the clogged filters.  That was an extreme fire season, but it was instructive. Now we stock up on HEPA filters.  You should, too! 

If you choose to get a PAC, plan on keeping it in the room where you spend the most time.  For example, it’s a good idea to run a PAC in your bedroom while you sleep.  Also, keep windows and doors to the room with the PAC closed to allow the machine to recirculate the air through its filter multiple times an hour. 

Keep in mind that HEPA filters do not remove the volatile organic compounds (VOCs) in smoke.  VOCs give smoke that campfire smell we all know so well, and they can make you feel pretty crummy.  While we generally consider the fine particulate matter in smoke to be the greater public health threat, VOCs are nasty business.  They’re also harder to remove from the air.  Generally, PACs with robust filters or technology to cut down VOCs will be quite a bit more expensive than your basic HEPA PAC.  A lot of HEPA PACs come with thin activated carbon pre-filters that are advertised to remove VOCs, but again, that’s for background concentrations.  The levels of VOCs in wildfire smoke will quickly saturate a thin prefilter. 

Important questions to ask when you look at an air cleaner:

  1. Does this unit use a true HEPA filter?

There are “HEPA-like” filters on the market, which are not the same thing as true HEPA and won’t be as effective at removing the fine particulate in smoke.  Remember, the fine particulate in smoke is less than 1 micron in diameter!  You want a filter that will remove the smallest particles possible, and that’s a true HEPA.

  1. How many square feet will it cover?

If you end up with an undersized air cleaner that is unable to recirculate the room’s air through its filter 2-3 times per hour, you likely won’t see significant indoor air quality improvements.

Also, keep in mind that the effective cleaning area is based on a room with 8-foot ceilings.  Do you have a luxuriously tall or vaulted ceiling? Fancy! Also, you’ll need to get your hands on a bigger air cleaner.  The more air you need to push through the filter, the larger machine you’ll need to purchase.

  1. Does this unit produce ozone?

Some air cleaners produce ozone, which is a criteria pollutant and harmful to human health.  Check to make sure the unit you are interested in has been approved by the California Air Resources Board (CARB) here: https://www.arb.ca.gov/research/indoor/aircleaners/certified.htm.  The CARB only approves units that do not produce harmful levels of ozone.

 Good questions to ask:

  1. Is this unit Energy Star rated?

Using less energy is good for the planet and your wallet!

  1. Is it noisy?

A PAC is only effective if it’s turned on, and it’s most effective if it’s turned all the way up. If you’re sensitive to noise, you’ll want to look for quieter models.  No matter what, expect some level of noise when you turn your PAC all the way up.  Fans can push a lot of air, and that will tend to generate noise.

  1. How expensive are replacement filters?

Do some legwork and find out how much the manufacturer charges for replacement filters.  You may also want to investigate filters offered by third parties. There are several companies making HEPA filters that will fit popular PAC models, and they often cost less than manufacturers’ filters.  Keep in mind, using third party filters may void the PAC’s warranty. 

Valuable question to ask:

  1. How effective is the unit at removing volatile organic compounds (VOCs)?

There are multiple methods for removing VOCs, but the most common one you’ll see is an activated carbon prefilter.  While activated carbon can remove VOCs, be aware that it can get saturated pretty quickly, which limits the effectiveness of a lot of the carbon prefilters on the market.  If you are concerned about the VOCs in smoke, you can plan on changing the prefilter out frequently or you can invest in an air cleaner with a robust activated carbon filter.  Note that the hefty activated carbon filters can be quite pricey.  Typically, the more fancy the VOC removal, the more expensive the machine (and the replacement filters).  For some folks, though, removing VOCs will be worth the price.

 That’s it on PACs for now.  Coming up in the next blog: using your central air handler for creating cleaner indoor air!

Top


 

June 26, 2019 

It's time to become wildfire-smoke-ready!

This is the first post in a short series of blogs about becoming a smoke-ready community. Stay tuned as we prepare for wildfire season!

Oh, hey! It’s suddenly summer!  Have you bought a new HEPA filter, yet?

That was one long, cold slog through spring, but summer has finally arrived, and we can get started on our summer to-do list: get outside and grill delicious foods, spend time on the river, hike in the mountains, enjoy the extra hours of daylight, and make a plan for creating cleaner air spaces in homes and businesses before wildfire season hits!

That’s right, folks.  There’s lightning in the hills and we’ve got smoke on the brain.  It’s time to become Smoke Ready. (It’s capitalized so you know it’s important.)

Wildfires in our region typically start in mid-July or August, and the clock’s ticking for getting ahead of summer wildfire smoke. Over the next couple weeks, I’ll be sending out some helpful information for preparing for this year’s wildfire season.  Now, the good news is we’re not supposed to have an extreme wildfire season in western Montana this year.  It’s supposed to be an average fire year and a potentially cooler and wetter summer than we typically see.  (And yeah, that feels right.  I, for one, greatly resented turning my heat on in June.) Keep in mind, though, that 2017 was *supposed* to be an average fire year.  Also, know who’s predicted to have a bad fire year? Washington.  And who’s sent us some of our worst out-of-state smoke? Also, Washington.  And who’s already had a large grass fire year? Again, Washington. The point being, even if we avoid local fires (and that’s a big if), there will likely be smoke this summer.  I mean, Canada’s been on fire for over a month now. Overachievers, the lot of them.

Wildfire smoke is nasty businesses.  It’s composed of a veritable stew of chemicals and fine particulate matter.  Most of the growing field of wildfire smoke health research has focused on the particulate matter in smoke, and really, there’s no good news there.  The fine particulate matter in wildfire smoke is super tiny (typically less than 1 micron in diameter), and it can bypass all your natural defenses to get deep into your lungs and even enter your bloodstream where it sets off an inflammatory response.  The pollutant is particularly harmful to infants, children, pregnant women, the elderly and anyone with heart or lung disease. It’s also just bad for everyone, particularly if you’re stuck in it for days or weeks at a time.  Folks who are sensitive to the smoke are most likely to experience respiratory effects such as worsening asthma attacks or difficulty breathing.  There’s also an increased risk of heart attacks and stroke for those with heart conditions.  The increased frequency of long duration wildfire smoke events is a relatively new phenomenon, so we don’t yet know what the long-term ramifications will be for children exposed to smoke.  We do know from a study in California that young children (ages 0-4) had a greater spike in asthma-related emergency department visits during a 2007 wildfire than any other age group.

Also, have you noticed how everyone just starts to feel crummy when smoke drags on?  When you’re in wildfire smoke for a prolonged period your body goes on the offensive.  An inflammatory response is really your body trying to get rid of an invader.  The strategy works pretty well when the invader is biological (such as a virus), but it’s less effective against particulate matter.  Exposure to fine particulate matter essentially sets in motion a prolonged immunological response.*  You feel crummy when you have a cold because your body is fighting off the invader.  It’s basically the same thing with smoke (albeit with less mucus).  Unfortunately, despite your body’s efforts, the most effective way to really get better is to get out of the smoke.  

Happily, we know how to get out of the smoke! Or, more accurately, get the smoke out of our breathing space.  Unfortunately, just going inside isn’t necessarily going to cut it.  You know how the super tiny fine particulate matter can get into your bloodstream? It can get into buildings, too.  The best way to make sure your indoor air is cleaner than the outdoor air is to actively filter out the fine particulate matter.  Now, the good news is the technology to filter fine particulate matter exists.  This isn’t an unknown realm or impossible task.  It takes some planning and an investment in good filters, but most people will be able to create cleaner indoor air when wildfire rolls into town.

I’ll take you into the weeds of creating cleaner indoor air spaces over the next couple weeks. We will go over picking out and using portable air cleaners (PACs) with true HEPA filters, the dos and don’ts of using your central air system to clean the air, some practical considerations for dealing with heat, air conditioners and wildfire smoke, and what we know about creating cleaner indoor air in large buildings. 

(If you caught this series last summer, some of the material will seem awfully familiar.  Also, I’m assuming you dutifully went out and secured PACs to create a cleaner air room in your home or bought a better HVAC filter for your central air system last year.  If so, don’t forget to stock up on new filters for the 2019 wildfire season!)

Also, if you don’t want to wait for my next update, head on over to www.montanawildfiresmoke.org for some great tips on preparing for wildfire season!

*With thanks to Sarah Henderson of the British Columbia Center for Disease Control for that explanation of why we all feel miserable in the smoke.  Sarah Henderson is one of my wildfire smoke heroes.  And yes, that’s a thing. There are some super rad, passionate scientists working to advance wildfire smoke science. Also, it’s nice to know that Canada sends us excellent science along with all the wildfire smoke.

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