Large circles on the map show Air Quality Index (AQI) values — for ozone and AQI2.5 — that are measured at official, outdoor permanent monitoring sites managed in the Bay Area by the Air Quality Management District and submitted to the U.S. EPA’s AirNow database. Smaller squares represent low-cost, privately owned PurpleAir sensors that show AQI2.5 using the EPA’s AirNow conversion. Data is updated hourly. To view wind and weather patterns, based on hourly weather station data provided by NOAA, click on the layer-list button in the top left corner and select “Current Weather and Wind Station Data.”
Want more information about air quality and wildfire smoke?
- How to protect yourself from wildfire smoke
- How to read air quality maps properly, from Purple Air to AirNow
- Masks for smoke and COVID: Which are best?
Here is an expanded list of other air quality measurement resources:
- U.S. Forest Service Air Monitoring Program
- Air Resource Board Breathewell for Mobile
- World Air Quality Index
AirNow is also running a project that adds data from low-cost sensors to a fire and smoke map.