Daily Air Quality Index summaries from EPA monitors in Black Hawk, Iowa, 1991–2025.
53%
Good days in 2025
49
Median daily AQI, 2025
2
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Black Hawk, Iowa on 365 days. 195 of those days (53%) were in the Good range, and the median daily AQI was 49. That median is higher than the typical monitored county in Iowa (median 43.5 across 14 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 365 days. Across the years with fuller monitoring, the share of Good days rose: an average of 48% in 2000–2002 versus 51% in 2023–2025.
Years with fewer than 120 monitored days (1996, 1997, 1998, 1999, 2003, 2007…) 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)
365
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
365
195
168
1
1
0
0
49
63
158
PM2.5
2024
365
215
150
0
0
0
0
47
59
87
PM2.5
2023
354
147
200
4
3
0
0
53
68
187
PM2.5
2022
364
232
132
0
0
0
0
44
59
84
PM2.5
2021
365
211
154
0
0
0
0
47
63
96
PM2.5
2020
366
239
127
0
0
0
0
42
59
92
PM2.5
2019
363
238
125
0
0
0
0
41
63
85
PM2.5
2018
365
140
225
0
0
0
0
53
66
84
PM2.5
2017
363
108
255
0
0
0
0
54
66
84
PM2.5
2016
364
179
184
1
0
0
0
51
62
118
PM2.5
2015
362
84
276
2
0
0
0
56
71
111
PM2.5
2014
364
91
272
1
0
0
0
56
71
117
PM2.5
2013
363
156
204
3
0
0
0
53
66
124
PM2.5
2012
362
160
202
0
0
0
0
52
68
99
PM2.5
2011
361
150
211
0
0
0
0
53
68
100
PM2.5
2010
360
161
192
7
0
0
0
52
74
113
PM2.5
2009
339
157
179
3
0
0
0
52
72
120
PM2.5
2008
131
73
56
2
0
0
0
47
65
115
PM2.5
2007
119
48
69
1
1
0
0
53
76
156
PM2.5
2006
121
69
51
1
0
0
0
46
65
102
PM2.5
2005
121
58
61
2
0
0
0
52
78
145
PM2.5
2004
122
70
51
1
0
0
0
44
65
108
PM2.5
2003
117
54
63
0
0
0
0
52
70
100
PM2.5
2002
122
58
64
0
0
0
0
53
72
82
PM2.5
2001
121
55
65
1
0
0
0
52
78
149
PM2.5
2000
123
64
58
1
0
0
0
49
77
102
PM2.5
1999
116
50
66
0
0
0
0
54
72
99
PM2.5
1998
53
52
1
0
0
0
0
25
43
60
PM10
1997
58
57
1
0
0
0
0
31
44
55
PM10
1996
57
55
2
0
0
0
0
26
44
69
PM10
1995
55
50
5
0
0
0
0
31
48
68
PM10
1994
51
49
2
0
0
0
0
25
41
56
PM10
1993
57
55
2
0
0
0
0
27
44
51
PM10
1992
42
35
7
0
0
0
0
28
54
68
PM10
1991
48
43
5
0
0
0
0
30
52
71
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 Iowa with a similar median AQI in 2025
