Daily Air Quality Index summaries from EPA monitors in Shoshone, Idaho, 1986–2025.
56%
Good days in 2025
44
Median daily AQI, 2025
1
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 Shoshone, Idaho on 363 days. 204 of those days (56%) were in the Good range, and the median daily AQI was 44. That median is higher than the typical monitored county in Idaho (median 35 across 18 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 360 days. Across the years with fuller monitoring, the share of Good days fell: an average of 80% in 1990–1995 versus 56% in 2023–2025.
Years with fewer than 120 monitored days (1987, 1988, 1989, 1991, 1992, 1993…) 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)
360
99%
Coarse particles (PM10)
3
1%
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
204
158
1
0
0
0
44
66
111
PM2.5
2024
366
209
156
1
0
0
0
46
66
112
PM2.5
2023
365
197
162
3
3
0
0
47
68
160
PM2.5
2022
365
217
141
4
3
0
0
42
71
172
PM2.5
2021
363
186
162
9
6
0
0
49
75
179
PM2.5
2020
366
221
138
0
3
3
1
41
68
440
PM2.5
2019
365
225
137
3
0
0
0
38
75
117
PM2.5
2018
365
157
195
12
1
0
0
53
85
153
PM2.5
2017
365
181
159
19
2
3
1
51
93
329
PM2.5
2016
366
196
165
5
0
0
0
47
73
150
PM2.5
2015
363
155
182
20
6
0
0
53
93
197
PM2.5
2014
365
186
165
13
1
0
0
49
82
151
PM2.5
2013
365
126
221
17
1
0
0
58
90
152
PM2.5
2012
366
199
161
6
0
0
0
44
79
133
PM2.5
2011
360
206
136
18
0
0
0
45
87
147
PM2.5
2010
365
162
180
22
1
0
0
54
94
156
PM2.5
2009
365
97
255
12
1
0
0
56
86
153
PM2.5
2008
366
133
217
13
3
0
0
55
90
157
PM2.5
2007
361
140
204
16
1
0
0
55
86
152
PM2.5
2006
353
183
164
6
0
0
0
49
77
129
PM2.5
2005
356
183
161
8
4
0
0
48
86
182
PM2.5
2004
357
193
154
10
0
0
0
46
78
134
PM2.5
2003
355
303
49
3
0
0
0
20
58
108
PM10
2002
345
288
50
7
0
0
0
19
68
139
PM10
2001
327
270
54
3
0
0
0
21
61
133
PM10
2000
325
291
34
0
0
0
0
17
52
90
PM10
1999
356
339
16
0
1
0
0
16
36
162
PM10
1998
242
233
8
1
0
0
0
18
36
112
PM10
1997
120
105
15
0
0
0
0
23
56
78
PM10
1996
120
110
10
0
0
0
0
25
50
77
PM10
1995
121
101
20
0
0
0
0
25
57
81
PM10
1994
121
95
26
0
0
0
0
30
59
95
PM10
1993
119
82
37
0
0
0
0
36
66
98
PM10
1992
108
87
21
0
0
0
0
32
60
90
PM10
1991
109
59
48
1
0
0
1
44
73
317
PM10
1990
120
93
27
0
0
0
0
31
58
94
PM10
1989
118
87
30
0
1
0
0
33
65
176
PM10
1988
102
57
43
2
0
0
0
44
72
115
PM10
1987
59
33
20
6
0
0
0
40
105
118
PM10
1986
43
22
17
3
0
1
0
50
95
225
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
