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.
Northern Zone
| Friday, May 6, 2016 |
Daily |
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
AQI |
18 | 16 | 15 | | 12 | 13 | 13 | 13 | 16 | 17 | 17 | 18 | 19 | 20 | 22 | | | | | | | | | |
23 |
30 | 29 | 28 | | 27 | 26 | 24 | 22 | 19 | 18 | 18 | 19 | 19 | 21 | 23 | | | | | | | | | |
24 |
21 | 19 | 16 | | 15 | 14 | 14 | 15 | 16 | 17 | 19 | 19 | 21 | 21 | 22 | | | | | | | | | |
22 |
29 | 29 | 29 | | 29 | 29 | 29 | 28 | 26 | 24 | 23 | 23 | 23 | 23 | 23 | | | | | | | | | |
28 |
Coast & Central Bay
| Friday, May 6, 2016 |
Daily |
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
AQI |
23 | 23 | 22 | | 22 | 23 | 24 | 25 | 25 | 26 | 25 | 25 | 25 | 25 | 25 | | | | | | | | | |
26 |
25 | 24 | 25 | | 24 | 25 | 25 | 24 | 24 | 24 | 23 | 23 | 23 | 24 | 23 | | | | | | | | | |
24 |
24 | 23 | 23 | | 24 | 25 | 25 | 25 | 25 | | 25 | 24 | 24 | 24 | 25 | | | | | | | | | |
25 |
25 | 25 | 24 | | 26 | 27 | 27 | 26 | 25 | 24 | 24 | 24 | 24 | 25 | 26 | | | | | | | | | |
27 |
Eastern Zone
| Friday, May 6, 2016 |
Daily |
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
AQI |
24 | 22 | 21 | | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 21 | 22 | | | | | | | | | |
24 |
26 | 24 | 23 | | 21 | 21 | 21 | 22 | 23 | 24 | 24 | 23 | 24 | 24 | 24 | | | | | | | | | |
24 |
19 | 19 | 18 | | 19 | 20 | 21 | 22 | 22 | 21 | 21 | 21 | 22 | 23 | 24 | | | | | | | | | |
25 |
25 | 24 | 24 | | 23 | 24 | 25 | 25 | 25 | 24 | 23 | 22 | 21 | 20 | 20 | | | | | | | | | |
26 |
30 | 29 | 29 | | 29 | 30 | 30 | 30 | 30 | 29 | 29 | 28 | | | | | | | | | | | | |
30 |
25 | 24 | 23 | | 23 | 23 | 24 | 25 | 25 | 25 | 24 | 24 | 23 | 23 | 22 | | | | | | | | | |
25 |
South Central Bay
| Friday, May 6, 2016 |
Daily |
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
AQI |
28 | 28 | 27 | | 27 | 27 | 27 | 27 | 26 | 25 | 24 | 24 | 23 | 23 | 22 | | | | | | | | | |
28 |
27 | 27 | 28 | | 28 | 27 | 27 | 26 | 24 | 23 | 22 | 22 | 21 | 21 | 22 | | | | | | | | | |
26 |
Santa Clara Valley
| Friday, May 6, 2016 |
Daily |
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
AQI |
21 | 19 | 18 | | 18 | 18 | 18 | 19 | 19 | 21 | 24 | 25 | 25 | 25 | 26 | | | | | | | | | |
28 |
15 | 12 | 12 | | 11 | 13 | 13 | 14 | 16 | 18 | 19 | 18 | 18 | 19 | 20 | | | | | | | | | |
22 |
27 | 27 | | | 27 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 19 | | | | | | | | | |
25 |
23 | 21 | 21 | | 21 | 22 | 23 | 23 | 25 | 26 | 27 | 27 | 27 | 27 | 28 | | | | | | | | | |
29 |