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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: PM2.5

PM2.5 is a term for fine particulate matter pollution.  PM2.5 is primarily a problem in the wintertime in the Bay Area, when wood burning constitutes the major source.

Daily AQI Measurements

Each cell in this chart shows the estimated hourly Air Quality Index (AQI) values for PM2.5.  

As established by the U.S. EPA, the AQI for PM2.5 is based on 24-hour concentrations, so hourly readings are only estimates.  

At the end of the day, a column at far right will show the preliminary AQI value for the day, based on the 24-hour average concentration.

If the number in the far right column at the end of the day is greater than 100, it means that PM2.5 levels were over the federal health standard.  Values between 101 and 150 in the far right column mean that air quality was in the Unhealthy for Sensitive Groups category for the day.  If the value in the far right column is greater than 150, that means air quality was in the Unhealthy category.

AQI Key
Northern Zone
Stations Tuesday, March 31, 2015
Hourly PST 01234567891011121314151617181920212223
Napa
43
42
42
42
38
40
45
43
41
30
24
26
28
30
26
32
35
32
San Rafael
34
36
32
33
37
38
38
38
33
29
32
45
64
69
63
61
63
60
Sebastopol
20
20
18
20
18
13
11
18
17
7
8
6
7
10
11
10
3
1
Vallejo
20
16
17
10
9
13
11
10
7
5
3
0
0
0
2
3
4
4
Coast & Central Bay
Stations Tuesday, March 31, 2015
Hourly PST 01234567891011121314151617181920212223
Laney College Fwy
32
26
25
25
31
41
59
50
48
45
33
29
25
19
24
29
33
38
Oakland East
20
22
24
22
22
23
20
22
28
28
27
28
45
57
46
42
42
44
Oakland West
46
42
40
34
27
32
33
31
26
19
30
30
27
24
20
25
29
31
San Francisco - Arkansas St.
16
22
22
25
30
25
19
26
21
21
17
17
31
28
39
38
38
35
San Pablo - Rumrill
24
20
10
11
25
25
21
19
13
11
16
14
13
19
18
22
34
31
Eastern Zone
Stations Tuesday, March 31, 2015
Hourly PST 01234567891011121314151617181920212223
Concord
34
38
31
22
25
21
17
17
15
14
15
14
20
22
22
21
21
17
Livermore - Rincon Ave.
20
22
26
21
15
12
14
22
19
14
9
9
10
20
25
27
26
21
South Central Bay
Stations Tuesday, March 31, 2015
Hourly PST 01234567891011121314151617181920212223
Redwood City
1
2
5
0
0
1
5
10
12
8
6
13
19
26
28
20
18
18
Santa Clara Valley
Stations Tuesday, March 31, 2015
Hourly PST 01234567891011121314151617181920212223
Gilroy
11
16
29
29
27
32
37
45
56
34
32
35
20
8
10
15
22
28
San Jose - Jackson St.
23
20
25
29
29
31
36
35
28
26
22
11
5
5
9
12
23
30
San Jose Fwy
20
15
9
5
2
12
20
18
11
8
8
6
1
0
1
7
12
12
Last Updated: 2/18/2015