This section contains selected maps that show how PM patterns change over the course of a given day, as placemarkers for the Air District's monitoring stations change color according to the Air Quality Index scale.
Although the Bay Area is one of the cleanest of the five major urban air basins in California, there are still several days annually when air pollution exceeds the state or federal air quality standards.
The links below depict daily particulate matter (PM) development patterns in the region. The placemarkers showing the PM monitoring stations on a Bay Area map change color over the course of a given day, reflecting the changes in Air Quality Index (or AQI) levels as pollution concentrations increase and subside.
Today’s Current Hour Still Image
Yesterday's Average (PM 2.5 only)
Note: Yesterday’s maps are not available until around 9am the following morning.
Air Quality Index
PM Health Effects