California(CA)

Name: EPA Air Quality System (AQS) Data
Creator: U.S. Environmental Protection Agency
License: https://www.usa.gov/government-copyright

Air quality overview and monitoring data — 2025

1,040

Monitoring Sites

33,522

Active Monitors

Counties with Data

365

Cities Monitored

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County Air Quality

YearMonth

County	Median AQI ▲	90th %ile	Max AQI	Good	Moderate	USG	Unhealthy
Siskiyou	6	9	10	15	0	0	0
Sonoma	9	18	39	273	0	0	0
Lake	17	29	32	34	0	0	0
Marin	21	29	32	20	0	0	0
Mono	22	44	104	168	12	1	0
Del Norte	33	54	70	145	34	0	0
Trinity	33	66	83	104	48	0	0
Solano	34	42	61	265	3	0	0
Humboldt	36	54	75	252	51	0	0
Tehama	36	54	90	171	41	0	0
Santa Cruz	37	57	71	148	33	0	0
Colusa	39	54	96	225	40	0	0
El Dorado	39	58	115	182	29	1	0
Amador	40	58	97	179	32	0	0
Glenn	40	54	94	170	42	0	0
Monterey	40	55	62	140	42	0	0
Tuolumne	40	58	87	175	35	0	0
San Benito	41	50	71	202	21	0	0
Calaveras	43	62	100	153	54	0	0
Madera	43	66	91	83	37	0	0
Merced	43	68	78	58	32	0	0
Nevada	44	61	84	144	37	0	0
San Joaquin	44	67	93	120	62	0	0
Shasta	44	54	100	197	35	0	0
Mariposa	45	61	90	204	46	0	0
Stanislaus	45	71	101	170	78	1	0
Plumas	46	82	111	103	88	4	0
Butte	47	59	96	162	83	0	0
Yolo	47	62	100	165	108	0	0
Sacramento	48	71	122	132	89	3	0
Sutter	48	67	100	130	82	0	0
Ventura	50	71	131	144	121	8	0
Placer	51	74	143	118	123	2	0
San Luis Obispo	51	69	119	120	146	7	0
Orange	52	77	159	122	143	8	1
Kings	53	85	105	72	106	3	0
Fresno	54	100	157	122	157	24	1
Inyo	54	84	163	111	151	8	3
San Diego	54	93	161	116	136	15	5
Santa Barbara	54	63	186	54	126	0	1
Tulare	59	105	140	69	133	30	0
Kern	61	100	143	65	183	25	0
Imperial	64	108	190	60	132	21	6
Los Angeles	77	151	201	30	155	59	30
Riverside	87	154	365	29	143	69	33
San Bernardino	90	164	207	34	137	61	42

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