Daily Air Quality Index summaries from EPA monitors in Clallam, Washington, 1987–2025.
85%
Good days in 2025
29
Median daily AQI, 2025
0
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Clallam, Washington on 365 days. 312 of those days (85%) were in the Good range, and the median daily AQI was 29. That median is about the same as 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 348 days. Across the years with fuller monitoring, the share of Good days fell: an average of 99% in 1987–1990 versus 86% in 2023–2025.
Years with fewer than 120 monitored days (1988) 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)
348
95%
Ozone
17
5%
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
365
312
53
0
0
0
0
29
53
69
PM2.5
2024
366
321
45
0
0
0
0
36
52
69
Ozone
2023
365
307
57
1
0
0
0
37
53
101
Ozone
2022
365
272
91
2
0
0
0
38
58
124
Ozone
2021
365
298
67
0
0
0
0
37
53
81
Ozone
2020
366
304
55
1
1
2
3
37
54
368
PM2.5
2019
365
285
80
0
0
0
0
38
56
73
PM2.5
2018
365
243
114
3
3
2
0
42
61
230
PM2.5
2017
365
246
111
4
4
0
0
41
64
188
PM2.5
2016
366
279
87
0
0
0
0
40
57
73
PM2.5
2015
364
263
101
0
0
0
0
41
58
80
PM2.5
2014
365
279
85
1
0
0
0
40
58
101
PM2.5
2013
365
297
68
0
0
0
0
37
59
85
Ozone
2012
366
242
124
0
0
0
0
43
61
83
PM2.5
2011
365
282
83
0
0
0
0
41
57
78
PM2.5
2010
365
316
49
0
0
0
0
38
52
67
Ozone
2009
364
248
116
0
0
0
0
42
59
89
PM2.5
2008
366
245
121
0
0
0
0
44
62
97
PM2.5
2007
363
258
103
2
0
0
0
40
64
105
PM2.5
2006
364
200
163
1
0
0
0
47
71
116
PM2.5
2005
365
227
137
1
0
0
0
41
67
111
PM2.5
2004
366
249
117
0
0
0
0
38
62
79
PM2.5
2003
365
249
116
0
0
0
0
39
65
82
PM2.5
2002
364
288
75
1
0
0
0
24
66
102
Ozone
2001
356
347
9
0
0
0
0
26
38
85
Ozone
2000
324
298
26
0
0
0
0
25
44
96
Ozone
1999
359
346
13
0
0
0
0
25
36
75
Ozone
1998
360
360
0
0
0
0
0
24
33
47
Ozone
1997
345
345
0
0
0
0
0
23
37
48
Ozone
1996
359
359
0
0
0
0
0
25
35
46
Ozone
1995
353
351
2
0
0
0
0
25
36
80
Ozone
1994
325
325
0
0
0
0
0
23
33
46
Ozone
1993
344
343
1
0
0
0
0
21
31
55
Ozone
1992
282
280
2
0
0
0
0
22
36
62
Ozone
1991
354
352
2
0
0
0
0
23
34
57
Ozone
1990
356
353
3
0
0
0
0
23
32
52
Ozone
1989
302
300
2
0
0
0
0
19
31
57
Ozone
1988
88
88
0
0
0
0
0
19
30
37
Ozone
1987
241
239
2
0
0
0
0
24
37
51
Ozone
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
