Tips to clean indoor air, stay healthy this wildfire season

It's Wildfire Smoke Ready Week in Missoula County! I know - after such a cool start to the season, it's challenging to shift gears and start thinking about wildfires. But this week of warm, sunny days is ushering us closer to our traditional wildfire season in Western Montana and that means smoke.

Smoke season in our area spans late July through early September. Happily, it is rarely smoky during that entire period but even a week or two of smoke can be a major bummer. In addition to obscuring our mountain views and sweet summer air, wildfire smoke is a serious health concern. It causes decreased lung function, worsened asthma attacks, worsened COPD symptoms, increased susceptibility to infectious disease and increased risk of stroke and heart attack.

Every year, at least one helpful smoke blog reader will tell me I need a giant fan to push smoke out of the valley. Well, yeah. That would be great! Sadly, the technology does not exist.

You know what does exist? Filters! I can't push smoke out of the valley but I can keep it out of my indoor breathing space using portable air cleaners (PACs), Do It Yourself (DIY) fan/filter combos and efficient Heating, Ventilation and Air Conditioning (HVAC) filters and you can too!

Here's what you need to know:

Filters

Not all filters are created equal. The best filters are High Efficiency Particulate Air (HEPA) filters. They are highly efficient at removing the tiny particles (smaller than one micron in diameter) we're most concerned about in smoke. HEPA filters are used in PACs and some commercial settings such as clean rooms.

Furnace filter efficiency is based on the Minimum Efficiency Reporting Values (MERV) scale. The higher the MERV, the better the filter. The current commercial standard for air filtration in Montana is a MERV 8, which is not designed for capturing tiny smoke particles. A MERV 13 or better will be more effective at cleaning the indoor air. A MERV 11 or 12 will do in a pinch.

** Save money by purchasing furnace filters in bulk online! A single MERV 13 filter can cost up to $30 but you can get that down to less than $10/filter if you buy in bulk. Stock up or split the purchase with friends or family!**

HEPA Portable Air Cleaners

A HEPA PAC, also known an as air purifier, uses a fan to pull air through a HEPA filter. Tiny smoke particles get trapped in the filter and cleaner air exits the machine. These are highly effective at cleaning indoor air on a room-by-room basis. Currently, a mid-size PAC costs around $150-$200.

1. The PAC should use a true HEPA filter and should NOT generate ozone.

2. Size the PAC appropriately for the room it is in. (The Clean Air Delivery Rate (CADR) should be similar to the room size. Note: CADR assumes eight-foot ceilings. Vaulted ceilings will need PACs with a bigger CADR.) Keep the PAC on a high setting to recirculate air through the filter 2-3 times per hour.

3. Investigate filter replacement costs and noise levels before making a purchase.

4. Keep extra filters on hand and replace when dirty.

DIY fan/filter combos

Did you notice a PAC is just a fan and a filter? Know what else is a fan and a filter and costs a lot less than a HEPA PAC? A box fan and a furnace filter stuck together!

1. Use a box fan manufactured after 2012 for safety (older box fans sometimes catch on fire).

2. Attach a MERV 13 furnace filter to the back of the fan.

3. The DIY fan/filter combo is good for a room about 200 square feet.

Homes with forced air for heating

You can clean the air throughout your home!

1. Install an efficient furnace filter (MERV 11, 12 or 13)

2. Run your furnace fan to pull air through the filter.

3. Replace the filter when it gets dirty.

Homes with central air for cooling

You may be the lucky duck who gets cool air and clean air at the same time!

Install the highest efficiency filter your system can use. Note: Some A/C systems cannot use a high efficiency filter because it may cause the coils to ice up. Investigate your system first!

Keep the fan turned on (decouple it from the thermostat) so it keeps cleaning.

Have extra filters on hand and replace when dirty.

If you cannot use high efficiency filters with your A/C, use portable air cleaners to clean the indoor air.

Commercial HVAC systems

Commercial spaces are harder to clean than homes but it's doable and the steps are nicely laid out in ASHRAE's Planning Framework for Protecting Commercial Building Occupants from Smoke During Wildfire Events, available here: https://www.montanawildfiresmoke.org/commercial-spaces.html

In brief:

1. Make sure the HVAC system is in good repair! When we investigated indoor air quality in commercial spaces, delayed HVAC maintenance was a major contributor to smoky indoor conditions.

2. Upgrade to the highest efficiency filter possible.

3. When it's smoky outside, limit the outdoor air intake as much as possible while maintaining positive pressure.

Outdoor activities

We live in the best part of the country. We either work outside or we want to spend the summer playing outside and smoke is never a welcome summer ingredient. Still, it is important to have a plan and know how to reduce your exposure when smoke rolls in.

1. Pay attention to changing conditions (If you cannot see five miles, the air quality is unhealthy).

2. Check hourly air quality at TodaysAir.mt.gov. or Fire.Airnow.gov.

3. Follow Missoula County's wildfire smoke forecasts at missoulacounty.us/currentaq! We have smoke jokes!

4. Reduce activity levels.

5. If you must be outside and the air is unhealthy, consider using an N95 respirator. Respirators must seal close to the face. Stop using it if you have difficulty breathing. Cloth masks don't work for wildfire smoke!

Learn more and prepare at MontanaWildfireSmoke.org and come find us at the Seeley Lake Sunday Market on July 17th!

Breathe safe!