Daily Air Quality Index summaries from EPA monitors in Kitsap, Washington, 1986–2025.
96%
Good days in 2025
22
Median daily AQI, 2025
0
Days above 100 in 2025
356
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Kitsap, Washington on 356 days. 340 of those days (96%) were in the Good range, and the median daily AQI was 22. That median is lower than the typical monitored county in Washington (median 28 across 30 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 356 days. Across the years with fuller monitoring, the share of Good days rose: an average of 84% in 1987–1989 versus 95% in 2023–2025.
Years with fewer than 120 monitored days (1998, 1999, 2000, 2001, 2002, 2003…) are shown in the table but left out of comparisons and trend statements.
How the days broke down each year
Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Typical and high-end AQI over time
The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.
Median daily AQI
90th-percentile daily AQI
Main pollutant by day, 2025
On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.
Pollutant
Days as main pollutant
Share of monitored days
Fine particles (PM2.5)
356
100%
Year-by-year data
Annual AQI summary by year
Year
Days with AQI
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Median AQI
90th pct.
Max AQI
Main pollutant
2025
356
340
16
0
0
0
0
22
42
61
PM2.5
2024
351
341
10
0
0
0
0
19
38
69
PM2.5
2023
349
323
25
1
0
0
0
22
44
115
PM2.5
2022
359
306
50
3
0
0
0
28
55
143
PM2.5
2021
359
342
16
1
0
0
0
26
44
113
PM2.5
2020
361
322
30
3
1
5
0
23
51
245
PM2.5
2019
340
313
27
0
0
0
0
24
47
77
PM2.5
2018
349
319
25
2
3
0
0
16
45
180
PM2.5
2017
360
326
29
5
0
0
0
19
47
144
PM2.5
2016
357
345
12
0
0
0
0
21
35
60
PM2.5
2015
358
333
25
0
0
0
0
23
44
84
PM2.5
2014
362
336
26
0
0
0
0
22
45
73
PM2.5
2013
349
311
38
0
0
0
0
22
52
78
PM2.5
2012
317
275
42
0
0
0
0
25
52
72
PM2.5
2011
361
288
72
1
0
0
0
27
58
110
PM2.5
2010
352
279
73
0
0
0
0
24
59
90
PM2.5
2009
356
246
106
4
0
0
0
33
64
126
PM2.5
2008
308
244
64
0
0
0
0
29
58
88
PM2.5
2007
361
272
88
1
0
0
0
32
63
102
PM2.5
2003
21
10
11
0
0
0
0
52
64
77
PM2.5
2002
54
36
18
0
0
0
0
42
66
82
PM2.5
2001
60
48
11
1
0
0
0
38
60
128
PM2.5
2000
63
39
24
0
0
0
0
46
64
72
PM2.5
1999
82
67
15
0
0
0
0
25
57
88
PM2.5
1998
61
61
0
0
0
0
0
12
19
33
PM10
1997
61
61
0
0
0
0
0
15
28
45
PM10
1996
227
227
0
0
0
0
0
17
31
42
CO
1995
364
361
3
0
0
0
0
19
34
60
CO
1994
163
162
1
0
0
0
0
24
38
54
CO
1993
61
58
3
0
0
0
0
16
44
54
PM10
1992
61
60
1
0
0
0
0
19
38
62
PM10
1989
364
346
18
0
0
0
0
24
41
66
CO
1988
363
292
70
1
0
0
0
28
59
103
CO
1987
358
274
83
1
0
0
0
33
71
106
CO
1986
53
38
15
0
0
0
0
34
61
77
CO
What this data can and can’t tell you
It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.
It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.
Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.
Counties in Washington with a similar median AQI in 2025
