Daily Air Quality Index summaries from EPA monitors in Klickitat, Washington, 1993–2025.
89%
Good days in 2020
22
Median daily AQI, 2020
9
Days above 100 in 2020
318
Days with an AQI in 2020 (of 366)
In 2020, EPA reported a daily Air Quality Index (AQI) for Klickitat, Washington on 318 days. 284 of those days (89%) were in the Good range, and the median daily AQI was 22. That median is lower than the typical monitored county in Washington (median 25.5 across 30 counties), and lower than the typical monitored U.S. county (39). The main pollutant was fine particles (PM2.5) on 318 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 84% in 1994–1996 versus 83% in 2018–2020.
Years with fewer than 120 monitored days (2017, 2021, 2022, 2023, 2024, 2025…) 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, 2020
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)
318
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
91
77
13
1
0
0
0
23
53
119
PM2.5
2024
106
101
5
0
0
0
0
17
43
64
PM2.5
2023
118
109
8
1
0
0
0
20
47
128
PM2.5
2022
117
103
14
0
0
0
0
18
52
96
PM2.5
2021
119
103
16
0
0
0
0
21
53
76
PM2.5
2020
318
284
25
0
2
0
7
22
51
1358
PM2.5
2019
365
300
65
0
0
0
0
27
54
97
PM2.5
2018
257
199
53
4
1
0
0
26
63
159
PM2.5
2017
119
105
11
2
1
0
0
21
53
152
PM2.5
2016
122
113
9
0
0
0
0
19
42
63
PM2.5
2015
120
107
12
1
0
0
0
21
52
108
PM2.5
2014
118
113
5
0
0
0
0
21
41
76
PM2.5
2013
118
108
10
0
0
0
0
18
46
70
PM2.5
2012
304
264
40
0
0
0
0
23
54
82
PM2.5
2011
175
141
34
0
0
0
0
25
55
91
PM2.5
2010
122
111
11
0
0
0
0
22
48
66
PM2.5
2009
122
107
15
0
0
0
0
28
52
65
PM2.5
2008
122
110
12
0
0
0
0
27
47
66
PM2.5
2007
121
108
13
0
0
0
0
24
52
73
PM2.5
2006
218
171
47
0
0
0
0
39
64
97
Ozone
2005
213
186
27
0
0
0
0
36
54
84
Ozone
2004
217
180
37
0
0
0
0
37
58
93
Ozone
2003
220
179
39
2
0
0
0
40
64
115
Ozone
2002
208
164
44
0
0
0
0
40
64
82
Ozone
2001
220
178
41
1
0
0
0
38
58
129
Ozone
2000
179
167
12
0
0
0
0
34
48
97
Ozone
1999
209
177
31
1
0
0
0
38
58
115
Ozone
1998
239
204
34
1
0
0
0
38
54
112
Ozone
1997
258
223
35
0
0
0
0
38
54
87
Ozone
1996
256
215
38
2
1
0
0
39
58
151
Ozone
1995
227
196
29
2
0
0
0
37
55
115
Ozone
1994
239
198
39
2
0
0
0
40
54
126
Ozone
1993
99
73
26
0
0
0
0
42
64
76
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.
