Air Monitoring Data

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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.

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.


* At this time, PM2.5 measurements at the Napa Valley College location are for informational purposes only.

AQI Key
Northern Zone
Stations Saturday, May 26, 2018 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Napa - Napa Valley College
26
26
25
25
0
San Rafael
23
24
24
25
0
Sebastopol
20
19
18
16
0
Vallejo
25
25
25
26
0
Coast & Central Bay
Stations Saturday, May 26, 2018 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Berkeley Aquatic Park
22
22
22
21
0
Oakland East
26
26
27
28
0
Oakland West
24
24
25
25
0
San Francisco - Arkansas St.
27
28
29
29
0
San Pablo - Rumrill
25
26
26
26
0
Eastern Zone
Stations Saturday, May 26, 2018 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Bethel Island
24
22
21
20
0
Concord
19
19
19
19
0
Fairfield - Chadbourne Rd.
23
23
22
22
0
Livermore - Rincon Ave.
24
23
23
24
0
San Ramon
26
26
26
27
0
South Central Bay
Stations Saturday, May 26, 2018 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Hayward
25
25
26
27
0
Santa Clara Valley
Stations Saturday, May 26, 2018 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Gilroy
23
22
21
20
0
Los Gatos
18
16
14
12
0
San Jose - Jackson St.
22
22
22
0
San Martin-Airport
22
21
19
20
0
Spare the Air Status
Spare the Air Status
  • Saturday,
    5/26

    No Spare the Air Alert in Effect

10/17/2017