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. View AQI flyer.

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.

Refresh this page to view the current day.


AQI Key 
Northern Zone
Stations Saturday, April 20, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Napa - Napa Valley College
21
20
19
19
19
19
19
19
19
19
21
23
25
San Rafael
21
21
21
22
22
23
23
25
27
29
31
32
35
Sebastopol
19
18
16
15
14
13
12
13
16
18
21
25
Vallejo
23
23
23
23
23
23
22
22
23
25
26
29
31
Coast & Central Bay
Stations Saturday, April 20, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Berkeley Aquatic Park
19
19
20
19
19
19
18
17
18
19
21
23
27
Oakland East
21
21
21
21
21
22
22
23
24
27
28
30
32
Oakland West
20
21
21
21
22
22
22
23
25
27
29
31
33
San Francisco - Arkansas St.
27
27
28
28
28
29
30
31
33
36
37
40
43
San Pablo - Rumrill
23
23
24
24
24
24
24
25
27
28
30
32
35
Eastern Zone
Stations Saturday, April 20, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Bethel Island
26
24
23
22
21
20
20
20
21
22
24
27
29
Concord
26
23
22
22
22
22
22
23
23
25
27
29
31
Fairfield - Chadbourne Rd.
21
20
20
19
19
19
19
19
19
19
19
21
22
Livermore - Rincon Ave.
27
24
22
21
21
21
22
22
24
27
28
31
33
San Ramon
26
23
21
21
21
21
22
23
25
27
29
31
32
South Central Bay
Stations Saturday, April 20, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Hayward
22
21
21
21
21
21
22
24
26
29
31
32
35
Redwood City
22
20
19
19
19
19
20
24
27
31
32
34
37
Santa Clara Valley
Stations Saturday, April 20, 2019 Daily
Hourly PST 01234567891011121314151617181920212223 AQI
Gilroy
20
19
19
20
20
19
19
19
18
18
18
19
19
Los Gatos
21
19
17
15
14
12
12
12
15
18
19
22
27
San Jose - Jackson St.
23
21
20
19
19
19
19
19
21
22
25
27
San Martin-Airport
23
22
21
20
19
19
18
16
16
16
17
18
19
Wood Burning Status
Wood Burning Status
  • Saturday,
    4/20

    No Spare the Air Alert in Effect