What the air quality number means
"The higher the AQI value, the greater the level of air pollution and the greater the health concern."
- 0 to 50GoodGreen"Air quality is satisfactory, and air pollution poses little or no risk."
- 51 to 100ModerateYellow"Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution."
- 101 to 150Unhealthy for Sensitive GroupsOrange"Members of sensitive groups may experience health effects. The general public is less likely to be affected."
- 151 to 200UnhealthyRed"Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects."
- 201 to 300Very UnhealthyPurple"Health alert: The risk of health effects is increased for everyone."
- 301 and higherHazardousMaroon"Health warning of emergency conditions: everyone is more likely to be affected."
Today's number where you live: AirNow.gov. During wildfires: the Fire and Smoke Map.
PM2.5, in EPA's words
EPA defines PM2.5 as "fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller".2 EPA: "Some particles less than 10 micrometers in diameter can get deep into your lungs and some may even get into your bloodstream." Of these, the fine particles, PM2.5, "pose the greatest risk to health".2
The AQI describes outdoor air. A monitor shows the PM2.5 inside.
A monitor for the air inside
Airthings View Plus: $329.99
Price checked October 1, 2026
Airthings says:3
- "PM2.5 is fine particulate matter small enough to reach deep into the lungs."
- "Typical sources include wildfire smoke, gas cooking, and candles."
The small commission from purchases made through this link helps keep this free public directory open, at no extra cost to you.
When wildfire smoke is the problem: Wildfire smoke.
Filtering what is left
Airthings Renew
Airthings says:4
- "Activated charcoal filter. Captures and holds gases (VOCs) and odors."
EPA: "Note that there are no widely used performance rating systems for portable air cleaners or filters designed to remove gases."5
The small commission from purchases made through this link helps keep this free public directory open, at no extra cost to you.
EPA: "EPA neither certifies nor recommends particular brands of air filters or home air-cleaning devices including portable air cleaners or purifiers."5
Sources
- AirNow, AQI Basics, checked October 4, 2026
- EPA, Particulate Matter (PM) Basics, checked October 4, 2026
- Airthings, View Plus product page, checked October 4, 2026
- Airthings, Renew product page, checked October 4, 2026
- EPA, Guide to Air Cleaners in the Home, checked October 4, 2026