Daily Air Quality Index summaries from EPA monitors in Madison, Indiana, 1989–2025.
71%
Good days in 2025
41
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 Madison, Indiana on 365 days. 260 of those days (71%) were in the Good range, and the median daily AQI was 41. That median is about the same as the typical monitored county in Indiana (median 41 across 33 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 192 days. Across the years with fuller monitoring, the share of Good days rose: an average of 59% in 1989–1994 versus 66% in 2023–2025.
Years with fewer than 120 monitored days (1990, 1991, 1992) 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
Ozone
192
53%
Fine particles (PM2.5)
173
47%
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
260
103
2
0
0
0
41
61
122
Ozone
2024
365
263
102
0
0
0
0
42
60
97
Ozone
2023
365
203
150
10
1
1
0
48
71
229
PM2.5
2022
365
224
137
4
0
0
0
45
66
133
PM2.5
2021
364
199
165
0
0
0
0
48
67
97
PM2.5
2020
366
233
133
0
0
0
0
44
59
97
PM2.5
2019
365
216
148
1
0
0
0
47
61
101
PM2.5
2018
365
199
159
7
0
0
0
48
63
136
PM2.5
2017
365
201
163
1
0
0
0
48
62
105
PM2.5
2016
358
224
134
0
0
0
0
44
64
97
PM2.5
2015
363
202
161
0
0
0
0
45
65
89
PM2.5
2014
335
151
182
2
0
0
0
52
71
141
PM2.5
2013
363
156
206
1
0
0
0
52
67
118
PM2.5
2012
352
146
196
9
1
0
0
53
80
151
PM2.5
2011
318
134
178
6
0
0
0
54
77
112
PM2.5
2010
290
136
154
0
0
0
0
53
75
100
PM2.5
2009
240
154
86
0
0
0
0
45
68
91
Ozone
2008
361
132
229
0
0
0
0
55
74
98
PM2.5
2007
350
106
229
15
0
0
0
60
90
150
PM2.5
2006
237
130
100
7
0
0
0
49
82
129
Ozone
2005
237
108
106
22
1
0
0
58
100
161
Ozone
2004
241
125
109
7
0
0
0
49
82
122
Ozone
2003
241
102
118
13
8
0
0
54
91
190
Ozone
2002
224
81
100
27
14
2
0
61
136
204
Ozone
2001
202
76
104
18
4
0
0
59
104
192
Ozone
2000
240
108
119
12
1
0
0
54
87
164
Ozone
1999
229
89
92
37
11
0
0
58
140
185
Ozone
1998
211
94
79
25
11
2
0
61
133
203
Ozone
1997
212
156
40
14
2
0
0
43
93
179
Ozone
1996
211
111
53
33
13
1
0
49
133
208
Ozone
1995
213
110
59
34
9
1
0
50
133
201
Ozone
1994
211
98
58
38
17
0
0
54
147
195
Ozone
1993
206
126
60
20
0
0
0
45
100
150
Ozone
1992
61
59
2
0
0
0
0
20
35
51
PM10
1991
60
56
4
0
0
0
0
22
47
57
PM10
1990
59
55
4
0
0
0
0
24
48
71
PM10
1989
220
150
53
15
2
0
0
44
93
154
Ozone
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 Indiana with a similar median AQI in 2025
