How we calculate air quality index
You can learn more about the air quality in your area with information provided by our partners and third-party sources.
- Government monitoring stations: Governments calculate air quality index (AQI) from station measurements. We display this AQI as-is.
- Non-regulatory partners: When the partner isn’t an official government monitoring station, we take their sensor measurements and calculate a weighted average using the NowCast algorithm. Then, we apply the US Environmental Protection Agency’s (US EPA) correction factor.
Data can be influenced by several factors like:
- Wind speed and direction
- Smoke plumes
- Other sources that emit fine particle pollution
Pollutant concentrations can be inconsistent over short distances and make air quality readings vary between locations. Other pollutants that aren’t included on the map can also affect air quality.
What are air sensors
Air sensors, also known as low-cost sensors, measure pollutants in the air. Air sensors are cheaper, more portable, and easier to operate than the government monitoring stations used by governments in the US. Learn more about air sensors.
Learn the difference between air sensor maps
Our air sensor map may be different from the US EPA Fire and Smoke Map.
Our process to add new air sensors is different from the US EPA process. We may show new air sensor stations before the US EPA does.