Pennington County, South Dakota air quality history
Daily Air Quality Index summaries from EPA monitors in Pennington, South Dakota, 1985–2025.
77%
Good days in 2025
32
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 Pennington, South Dakota on 364 days. 282 of those days (77%) were in the Good range, and the median daily AQI was 32. That median is lower than the typical monitored county in South Dakota (median 35.5 across 10 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 221 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1985–1987 versus 68% in 2023–2025.
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)
221
61%
Coarse particles (PM10)
139
38%
Nitrogen dioxide (NO₂)
4
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
364
282
81
1
0
0
0
32
62
107
PM2.5
2024
366
248
114
4
0
0
0
36
68
111
PM2.5
2023
365
216
140
5
4
0
0
45
70
172
PM2.5
2022
363
238
123
2
0
0
0
40
69
116
PM2.5
2021
365
244
114
5
1
1
0
39
73
202
PM2.5
2020
366
264
102
0
0
0
0
35
64
92
PM2.5
2019
361
267
90
4
0
0
0
33
61
117
PM10
2018
365
263
100
2
0
0
0
36
61
118
PM2.5
2017
365
264
96
4
1
0
0
37
59
152
PM2.5
2016
366
284
81
1
0
0
0
33
58
101
PM2.5
2015
365
182
180
3
0
0
0
51
65
120
PM2.5
2014
365
258
107
0
0
0
0
38
59
89
PM2.5
2013
365
214
151
0
0
0
0
44
61
94
PM2.5
2012
366
259
107
0
0
0
0
38
59
79
PM2.5
2011
364
288
76
0
0
0
0
33
56
94
PM10
2010
365
298
67
0
0
0
0
33
55
93
PM2.5
2009
365
247
118
0
0
0
0
37
60
92
PM2.5
2008
364
292
71
0
1
0
0
32
58
156
PM10
2007
362
262
100
0
0
0
0
35
57
78
PM10
2006
365
258
105
2
0
0
0
44
61
108
Ozone
2005
363
240
121
2
0
0
0
44
64
119
PM10
2004
366
229
136
1
0
0
0
45
66
102
PM10
2003
331
207
118
6
0
0
0
45
77
122
PM10
2002
347
212
129
6
0
0
0
45
74
122
PM10
2001
354
248
104
2
0
0
0
37
63
109
PM10
2000
366
248
117
0
0
1
0
42
65
247
PM10
1999
240
157
81
2
0
0
0
42
65
111
PM10
1998
365
332
33
0
0
0
0
26
50
87
PM10
1997
365
262
101
2
0
0
0
35
65
135
PM10
1996
366
278
85
3
0
0
0
34
58
137
PM10
1995
364
287
77
0
0
0
0
34
57
99
PM10
1994
360
275
85
0
0
0
0
36
59
95
PM10
1993
362
311
51
0
0
0
0
22
55
92
PM10
1992
359
302
55
2
0
0
0
27
54
118
PM10
1991
263
237
24
2
0
0
0
21
50
110
PM10
1990
171
140
31
0
0
0
0
25
57
80
PM10
1989
167
152
15
0
0
0
0
21
45
72
PM10
1988
158
145
13
0
0
0
0
24
49
86
PM10
1987
171
158
13
0
0
0
0
27
45
93
PM10
1986
169
153
16
0
0
0
0
24
50
93
PM10
1985
156
130
26
0
0
0
0
33
57
81
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 South Dakota with a similar median AQI in 2025
