The map below, updated hourly, shows air quality in the Bay Area. The EPA also posts the Air Quality Index for dozens of California cities. The Bay Area air quality district lists current and recent AQI from individual monitoring stations. The private company PurpleAir maintains an interactive, crowdsourced air quality map. Check here for a complete list of resources. Here is how to protect yourself from wildfire smoke.
Below is an interactive, crowdsourced air quality map from the private company PurpleAir, which relies on many more sensors than the BAAQMD.
Here is an expanded list of other air quality measurement resources: