Making Sense of the Air Quality Index

The fire season in the Western United States this year has been unlike any before, degrading air quality for millions of Americans. To help you understand your area’s air quality and learn how to protect your family’s health, we’ve compiled some frequently asked questions and answers. 

Clean air

Staff photo, Oregon. September 8, 2020.

The fire season in the Western United States this year has been unlike any before. In the last few weeks, fires have burned millions of acres of land in California, Oregon, and Washington.[1] Tens of thousands of people have been forced to evacuate in the midst of a pandemic.[2] Smoke has covered the entire western half of the U.S., and some cities have the worst air quality of the major cities around the world.[3]

But, many people are asking: We’ve been hearing a lot about air quality and indexes and orange and purple and “350” and “107.” What is all this jargon? What does air quality really mean, for our daily lives and for our health? If I’m healthy, do I really need to be concerned about this? 

The answer is YES, regardless of health, we all need to be concerned about breathing smoke. To help you understand your area’s air quality and learn how to protect your family’s health, we’ve compiled some frequently asked questions and answers. 

What is the Air Quality Index?
Who is most affected by poor air quality? 
Where do I find my local air quality? 
What should I do when I have poor air quality? 
Can I wear a mask to protect myself from the smoke?
How unhealthy is poor air quality, really?

For more detailed information, see the Environmental Protection Agency’s Guide to AQI and your Health.
For more detailed information for those with lung disease, heart conditions, or Diabetes, see the American Lung Association’s tips: Wildfires
For more detailed information about COVID-19 and wildfires, see the Centers for Disease Control and Prevention’s tips: Wildfire Smoke and COVID-19

What is the Air Quality Index? 

The Air Quality Index (AQI) is a measurement created by the EPA to tell us how healthy our air is to breathe.[4] It’s important for everyone to understand — whether you have existing respiratory conditions or are perfectly healthy, and whether you live in the West or in the unaffected eastern states. The numbers you are hearing on the news are simply a calculation of how poor the air quality is based on the presence of 5 pollutants: ground level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and particle pollution.[5] Exposure to any of these pollutants can cause serious health effects for everyone. But with wildfire smoke, one of the most concerning types of pollutants is particle pollution, especially particles that are very small, referred to as PM 2.5.[6,7] This type of particle pollution can cause devastating health effects for the lungs and heart.[8]

Depending on where you’re getting your air quality information, you may hear it described as either a number or a color. This chart shows you what those numbers and colors mean in relation to one another and to the level of health concern. Think of this chart like a stop light: if it’s green, you can go outside. If it’s yellow or orange, think twice (especially if you’re part of a “sensitive group” — see below). If it’s red, stay inside. If it’s purple or maroon, take extra precautions to protect yourself. (More detailed info below on precautions to take under each level.)

Who is most affected by poor air quality?

“Sensitive” groups include children, the elderly, and people with lung conditions, heart conditions, or diabetes (including asthma and viral infections).[9] It’s especially important to keep your kids inside when air quality is bad (even if they have been cooped up all day staring at a Zoom screen). Sensitive groups should try to remain inside with windows closed, especially in areas where the AQI is red, purple, or maroon. 

Where do I find my local air quality? 

You can find out your air quality from many different sources. Online sources include and You can also try googling “AQI, my city.”  Many weather apps for mobile devices list air quality. Many local news stations for TV and radio may provide updates. For many of us in the West, we can tell by looking out the window. If the haze from the smoke is easily visible, then it’s a good bet that it’s time to stay inside, even if you’re healthy. 

What should I do when I have poor air quality? What are the recommendations for each AQI level?

The smoke is a serious situation and should not be taken lightly. 

Orange – When the air quality is orange, everyone should reconsider their plans for the day. Sensitive groups should avoid outdoor exposure, and everyone should avoid extended periods of strenuous activity in the outdoors.[10] 

Red – Stay inside when you can; every hour of time spent outside adds to the health risk. Sensitive groups should be extra careful to limit time spent outside.[11] Instead, find ways to exercise and entertain yourself indoors. 

Here are some resources to get you started: 

25 Public Interest Challenges for Kids

50 Environmentally Friendly activities Kids can do at Home

Purple or Maroon – Take extra precautions. Stay inside, close your windows and fireplaces, and place a damp cloth under all doors that open to the outdoors. Make sure you invest in a good air filter for your conditioning system. Try putting your system on the “recirculate” setting. If you must drive somewhere, close the windows and vents and put the AC on the “recirculate” setting.[12]

Pay attention to local alerts and news to find out if you will be evacuated. 

Can I wear a mask to protect myself from the smoke?

Opt to stay indoors if possible, but if you must be outside, N-95 masks are effective.[13] But remember, a mask is only effective if it fits correctly. Also, keep in mind that N-95 masks are needed for healthcare work in the pandemic and are likely in short supply. N-95 masks reduce airflow; people with lung conditions should consult with their doctor before using them.[14] 

How unhealthy is poor air quality, really?

Doctors and scientists are very concerned about the effects of the poor air quality in the West. Short term, poor air quality due to particle pollution can cause healthy people to develop headaches, throat and eye irritation, lung inflammation, and may cause them to be more prone to respiratory infections.[15,16] PM 2.5 is of particular concern because the very small particles can bury deep into the lungs and even get into the bloodstream.[17] Long term, exposure to particle pollution is linked to lung disease, heart disease, heart attacks, and decreased lung function.[18]

Unfortunately, COVID-19 doesn’t stop when fires start. The overlap of the pandemic and the hazardous air quality makes this situation especially concerning. Exposure to hazardous air, especially for days and weeks, can impact our immune systems and makes us more prone to viral lung infections.[19] The evacuations in the west are making this situation even more complicated. To the best of our ability, we need to continue social distancing and avoiding exposure to smoke. While cloth masks do not protect us from smoke, they do protect us from spreading the virus. 

Air quality should not be taken lightly. Following the safety steps provided in this guide can help to keep you and your family healthy. 


  1. “At least 35 dead as wildfires rampage along the west coast” NPR. Sept 14, 2020.

  2.  “Wildfires: Thousands evacuated, may be weeks until they go Home” The American Red Cross. Sept 15, 2020. 

  3.  The Western US has the worst air quality in the world, group says CNN. Sept 14, 2020. 

  4.  “AQI Basics” AirNow.

  5. See note 4.

  6.  “Health and Environmental Effects of Particulate Matter (PM)” U.S. Environmental Protection Agency. 

  7.  “How wildfires affect our health” American Lung Association. Jan 22, 2016.

  8. See note 6.

  9. “Air Quality Index” American Lung Association. Updated Sept 11, 2020.

  10. See note 9.

  11.  See note 9.

  12. “Wildfires” American Lung Association. Updated Sept 15, 2020. 

  13. See note 12.

  14. See note 12.

  15.   “Protect yourself from wildfire smoke” Centers for Disease Control and Prevention. Aug 3, 2020.

  16.  “Wildfire Smoke and COVID-19” Centers for Disease Control and Prevention. Aug 25, 2020.

  17. See note 6.

  18. See note 6.

  19. See note 16.