Daily Air Quality Index summaries from EPA monitors in Lake, Oregon, 1991–2025.
80%
Good days in 2025
26
Median daily AQI, 2025
1
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Lake, Oregon on 364 days. 293 of those days (80%) were in the Good range, and the median daily AQI was 26. That median is lower than the typical monitored county in Oregon (median 29 across 21 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 364 days. Across the years with fuller monitoring, the share of Good days fell: an average of 82% in 1992–1994 versus 77% in 2023–2025.
Years with fewer than 120 monitored days (1991, 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)
364
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
364
293
70
1
0
0
0
26
62
105
PM2.5
2024
366
286
71
7
2
0
0
28
66
153
PM2.5
2023
365
266
98
1
0
0
0
28
63
134
PM2.5
2022
365
273
88
4
0
0
0
25
65
129
PM2.5
2021
365
240
102
17
6
0
0
28
85
188
PM2.5
2020
365
267
80
14
4
0
0
29
70
166
PM2.5
2019
363
288
74
1
0
0
0
25
61
106
PM2.5
2018
358
244
92
13
9
0
0
34
82
191
PM2.5
2017
363
258
87
14
4
0
0
29
75
166
PM2.5
2016
360
300
58
1
1
0
0
24
58
161
PM2.5
2015
365
270
92
3
0
0
0
28
68
125
PM2.5
2014
363
275
75
12
1
0
0
29
68
157
PM2.5
2013
363
211
114
18
20
0
0
43
108
198
PM2.5
2012
350
241
96
12
1
0
0
32
75
152
PM2.5
2011
364
264
80
15
5
0
0
28
83
165
PM2.5
2010
364
279
83
2
0
0
0
28
61
118
PM2.5
2009
363
246
96
15
6
0
0
34
82
173
PM2.5
2008
365
238
113
11
3
0
0
33
82
165
PM2.5
2007
362
284
74
4
0
0
0
27
69
122
PM2.5
2006
360
287
67
6
0
0
0
28
62
132
PM2.5
2005
361
281
64
15
1
0
0
26
67
151
PM2.5
2004
366
292
74
0
0
0
0
26
65
96
PM2.5
2003
93
89
4
0
0
0
0
24
44
88
PM2.5
2002
357
258
89
8
2
0
0
31
73
167
PM2.5
2001
361
281
77
3
0
0
0
29
60
105
PM2.5
2000
336
276
53
7
0
0
0
26
60
138
PM2.5
1999
208
155
49
2
2
0
0
31
67
154
PM2.5
1998
181
171
10
0
0
0
0
13
38
78
PM10
1997
202
194
8
0
0
0
0
17
36
73
PM10
1996
210
203
7
0
0
0
0
15
40
67
PM10
1995
216
195
21
0
0
0
0
20
50
75
PM10
1994
208
179
27
2
0
0
0
22
59
115
PM10
1993
213
164
45
3
1
0
0
27
64
151
PM10
1992
225
186
38
1
0
0
0
26
62
101
PM10
1991
79
55
21
3
0
0
0
33
77
133
PM10
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 Oregon with a similar median AQI in 2025
