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Air Monitoring Data

This page provides access to current and historical air quality and meteorological information based on measurements taken at stations in the Air District’s air monitoring network. Some of the data on these pages is raw or unchecked data that may contain errors.

How to Use the Air Monitoring Data Page

Measurement: Ozone (O3)

Ozone (O3) is the main ingredient in summertime smog.

Daily AQI Measurements

Each cell in this chart shows the running 8-hour average Air Quality Index (AQI) values for ozone, ending with that hour.  As established by the U.S. EPA, the AQI for ozone is based on the 8-hour average concentration.

The column at far right shows the preliminary AQI value for that day, which is based on the highest 8-hour average concentration during that 24-hour period.

If the number in the far right column is greater than 100, it means that there was an exceedance of the federal health standard.  Values between 101 and 150 in the column at the far right mean that air quality was in the Unhealthy for Sensitive Groups category for the day.  If the value at the far right is greater than 150, that means air quality was in the Unhealthy category.


AQI Key
Northern Zone
Stations Monday, May 25, 2015 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Napa
31
30
30
29
29
28
27
26
25
25
25
26
26
27
31
San Rafael
28
28
28
27
27
26
26
25
25
25
25
25
25
25
28
Sebastopol
27
27
26
26
25
25
25
23
22
21
21
21
21
22
27
Vallejo
30
30
30
29
29
28
28
28
28
27
27
28
28
28
30
Coast & Central Bay
Stations Monday, May 25, 2015 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Oakland East
29
29
28
28
27
27
27
27
27
27
27
27
27
28
29
Oakland West
27
26
25
25
25
25
24
25
25
25
25
25
26
27
27
San Francisco - Arkansas St.
29
28
28
27
27
27
27
27
27
27
27
27
28
28
29
San Pablo - Rumrill
29
29
29
29
28
28
27
27
26
26
26
26
27
27
29
Eastern Zone
Stations Monday, May 25, 2015 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Bethel Island
29
28
26
24
22
21
20
20
21
24
25
27
30
31
31
Concord
30
30
30
29
28
28
28
28
27
27
28
28
29
29
30
Fairfield - Chadbourne Rd.
30
30
30
29
28
27
27
26
26
27
27
27
28
28
30
Livermore - Rincon Ave.
30
30
29
29
28
28
28
27
27
27
27
28
29
30
30
San Ramon
30
30
30
29
28
27
27
26
26
25
26
26
26
27
30
South Central Bay
Stations Monday, May 25, 2015 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Hayward
31
30
30
29
28
27
27
26
26
26
26
27
27
28
31
Redwood City
31
31
30
29
29
28
27
27
26
26
27
27
27
27
31
Santa Clara Valley
Stations Monday, May 25, 2015 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Gilroy
26
25
25
25
25
25
25
24
24
23
23
24
25
25
26
Los Gatos
28
27
26
25
23
21
20
18
17
17
18
19
22
24
28
San Jose - Jackson St.
30
29
29
28
27
26
25
25
25
25
25
26
27
30
San Martin-Airport
28
27
27
25
25
25
24
23
23
22
23
24
25
25
28
Last Updated: 2/18/2015