Daily Air Quality Index summaries from EPA monitors in Canyon, Idaho, 1993–2025.
77%
Good days in 2025
36
Median daily AQI, 2025
0
Days above 100 in 2025
363
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Canyon, Idaho on 363 days. 280 of those days (77%) were in the Good range, and the median daily AQI was 36. That median is about the same as the typical monitored county in Idaho (median 35 across 18 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 336 days. Across the years with fuller monitoring, the share of Good days fell: an average of 81% in 1999–2001 versus 73% in 2023–2025.
Years with fewer than 120 monitored days (1993, 1994, 1995, 1996, 1997, 1998) 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)
336
93%
Coarse particles (PM10)
27
7%
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
363
280
83
0
0
0
0
36
58
91
PM2.5
2024
366
248
103
9
6
0
0
36
73
183
PM2.5
2023
364
268
96
0
0
0
0
34
59
88
PM2.5
2022
364
189
167
7
1
0
0
49
76
155
PM2.5
2021
365
209
147
5
4
0
0
46
71
172
PM2.5
2020
366
210
140
10
6
0
0
42
76
158
PM2.5
2019
365
285
80
0
0
0
0
32
58
95
PM2.5
2018
365
254
106
5
0
0
0
35
69
134
PM2.5
2017
365
227
121
13
4
0
0
40
75
168
PM2.5
2016
366
187
175
4
0
0
0
50
67
117
PM2.5
2015
364
262
92
8
2
0
0
34
62
156
PM2.5
2014
365
346
18
0
1
0
0
15
40
158
PM10
2013
312
275
33
3
1
0
0
23
52
196
PM10
2012
349
295
52
0
2
0
0
18
55
179
PM10
2011
358
328
29
1
0
0
0
19
44
110
PM10
2010
360
262
97
1
0
0
0
30
61
127
PM2.5
2009
289
262
27
0
0
0
0
21
50
72
PM10
2008
287
210
77
0
0
0
0
36
58
99
PM2.5
2007
362
194
166
2
0
0
0
48
70
141
PM2.5
2006
358
211
143
4
0
0
0
44
71
115
PM2.5
2005
365
237
118
9
1
0
0
44
74
151
PM2.5
2004
366
239
122
5
0
0
0
44
63
134
PM2.5
2003
365
267
95
3
0
0
0
43
65
111
Ozone
2002
365
242
112
9
2
0
0
44
74
171
Ozone
2001
365
295
63
5
2
0
0
35
59
166
CO
2000
366
303
59
4
0
0
0
33
57
117
CO
1999
361
287
73
0
1
0
0
37
57
151
CO
1998
68
51
17
0
0
0
0
28
62
98
PM10
1997
58
51
7
0
0
0
0
31
51
63
PM10
1996
57
49
8
0
0
0
0
31
55
89
PM10
1995
59
49
10
0
0
0
0
34
60
64
PM10
1994
59
46
13
0
0
0
0
35
62
80
PM10
1993
25
18
7
0
0
0
0
38
60
66
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 Idaho with a similar median AQI in 2025
