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.


Refresh this page to view the current day.


AQI Key 
Northern Zone
Stations Thursday, May 23, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Napa - Napa Valley College
20
19
17
16
15
14
15
17
18
19
20
23
25
San Rafael
25
23
21
19
16
13
11
10
12
13
14
16
19
Sebastopol
15
12
8
6
6
4
5
6
7
8
11
14
18
Vallejo
24
23
21
20
19
19
19
19
19
19
20
22
24
Coast & Central Bay
Stations Thursday, May 23, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Berkeley Aquatic Park
19
19
20
20
20
20
19
19
18
17
17
17
20
Oakland East
24
24
23
23
22
21
20
20
19
19
20
21
22
Oakland West
21
21
21
22
22
21
21
20
20
21
21
22
23
San Francisco - Arkansas St.
26
25
23
21
20
19
19
19
20
21
22
23
25
San Pablo - Rumrill
23
22
22
21
22
22
21
21
21
22
23
24
25
Eastern Zone
Stations Thursday, May 23, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Bethel Island
20
19
17
17
17
17
17
18
19
20
22
25
28
Concord
23
22
20
20
19
19
19
19
19
19
22
24
27
Fairfield - Chadbourne Rd.
22
21
20
19
19
18
18
18
19
20
21
24
26
Livermore - Rincon Ave.
24
23
22
19
16
15
15
14
15
16
19
22
27
San Ramon
20
19
18
16
16
15
16
16
16
17
19
21
24
South Central Bay
Stations Thursday, May 23, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Hayward
28
27
26
25
24
23
22
21
20
20
21
23
24
Redwood City
23
21
18
15
12
10
9
8
9
11
14
16
20
Santa Clara Valley
Stations Thursday, May 23, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Gilroy
23
21
19
19
20
20
21
22
23
24
24
24
25
Los Gatos
18
16
15
13
13
13
13
13
13
13
14
15
17
San Jose - Jackson St.
23
22
19
19
18
18
18
19
19
20
22
24
San Martin-Airport
29
27
26
25
25
24
24
24
24
24
24
25
25
Spare the Air Status
Spare the Air Status
  • Thursday,
    5/23

    No Spare the Air Alert in Effect