AQMIS (Air Quality and Meteorological Information System) provides real time and historical air quality data. 

How to use AQMIS (example):

1. Click AQMIS to start
2. Select "Air Quality Data"
3. Select either the Daily or Hourly Data tab\
4. Select the particulate you wish to view (i.e. PM2.5)
5. Select a date
6. Select the County, Air Basin, or Part of the State
7. Select "Retrieve Data"