How Does Wildfire Smoke Impact Indoor Air Quality?

Buy ElementBuy Omni



September 28, 2020

To better understand the impact unhealthy outdoor air quality has on indoor environments, Awair aggregated data from its indoor air quality (IAQ) monitors during the smoked-filled air days due to fires along the West Coast of the United States. 

On the days outdoor air was rated “Very Unhealthy” by (Sept 9 and the days following), indoor air quality within a 30 mile radius of the San Francisco Bay Area had, on average:

Typical noon in SF (top); same view noon Sept 9, 2020 (bottom)

While people indeed remained much safer from PM2.5 exposure by staying indoors, the amount of PM2.5 (fine dust) indoors was surprising to us - and worrisome. Extended exposure to high PM2.5 can cause serious health damage and/or exacerbate pre-existing conditions such as asthma or other respiratory illnesses. Moreover, exposure to PM2.5 that high can lay the groundwork for future illnesses in certain individuals.  


The above graph illustrates the spike in PM2.5 readings on indoor air quality monitors  within 30 miles of the SF Bay Area.  

CO2 also saw a big spike (300 points) within the same timeframe. High CO2 can cause drowsiness, headaches, decreased productivity, and/or difficulty with decision-making. If you were especially lethargic and struggling to stay awake during your Zoom calls in the Bay Area mid-September, you certainly weren’t alone.

CO2-w (1)

This graph illustrates the spike in CO2 readings on and around Sept 9, 2020, the day the sky was orange in SF.

In addition, TVOCs were up nearly three times the usual. TVOCs can come from cooking and cleaning, amongst other materials found in the home. We had already noticed occasional spikes in TVOCs as people have been cleaning and sheltering in place for COVID-19, and this rate was even higher. 


This graph illustrates the increase in TVOCs readings during 'Very Unhealthy' air alert days.

Now What?

For people entirely new to indoor air quality, here are a few of the above air quality factors explained in more detail. While we were not surprised to find indoor air quality was negatively impacted by the recent poor air quality outside, the amount by which detrimental air factors went up was very eye-opening.

We would like to first raise awareness that outdoor air, such as the recent Very Unhealthy air quality days across the West Coast, can significantly impact PM2.5 and key air factor exposure not just a little but by a factor of five, even for those that stay inside with closed windows.

More importantly, there are proactive solutions one can take to prepare in advance for unhealthy air days that may happen in the future, due to smoke or otherwise. Our wildfire safety guide has a great tip on creating a safe room as well as other useful information. Purchasing an air filter and/or keeping your central air HVAC air filters updated and clean can help the next time we see a spike. While many air filters listed are sold out at the time of this writing, we have suggestions on quality devices at our Favorites page. Finally, there is a creative but worthwhile solution people are taking to build a DIY air filter as well, which may be helpful as air filter companies struggle to meet demand. 

These types of extreme outdoor air events and data findings are new to us as well. Our hope is that by sharing information, we can help keep people informed on how to stay healthy when the air isn’t.

You can understand and keep track of PM2.5, TVOCs, CO2, Temperature, & Humidity in your home and use that information to manage your indoor air for health & safety by using Awair Element. We also offer custom enterprise solutions in connectivity, power, and installation for building owners, mid to small businesses, and employers as well. Please review our Enterprise Solutions and use the contact form to get more information specific to your needs. 




  • PM2.5 levels that were five times higher than usual; equating to levels five times higher than the World Health Organization's recommended exposure per 24 hours.
  • CO2 increased an average of 300 points, likely because people were closing windows to prevent the worse outdoor air from coming in.
  • TVOCs tripled.