Daily Air Quality Index summaries from EPA monitors in Dubois, Indiana, 1984–2025.
70%
Good days in 2025
39
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 Dubois, Indiana on 363 days. 253 of those days (70%) were in the Good range, and the median daily AQI was 39. 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 fine particles (PM2.5) on 363 days. Across the years with fuller monitoring, the share of Good days rose: an average of 21% in 2004–2006 versus 69% in 2023–2025.
Years with fewer than 120 monitored days (2002, 2003, 2009, 2010, 2011, 2018…) 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)
363
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
363
253
110
0
0
0
0
39
58
88
PM2.5
2024
366
265
101
0
0
0
0
39
57
70
PM2.5
2023
239
152
86
1
0
0
0
44
60
130
PM2.5
2022
123
80
43
0
0
0
0
42
58
88
PM2.5
2021
125
77
48
0
0
0
0
43
64
94
PM2.5
2020
123
78
45
0
0
0
0
44
59
71
PM2.5
2019
120
76
44
0
0
0
0
43
59
73
PM2.5
2018
119
71
48
0
0
0
0
42
62
89
PM2.5
2017
120
83
37
0
0
0
0
42
60
72
PM2.5
2016
127
78
49
0
0
0
0
44
60
76
PM2.5
2015
122
65
57
0
0
0
0
47
64
79
PM2.5
2014
122
49
73
0
0
0
0
53
69
97
PM2.5
2013
120
49
71
0
0
0
0
54
68
78
PM2.5
2012
123
50
73
0
0
0
0
53
68
82
PM2.5
2011
119
41
77
1
0
0
0
56
74
109
PM2.5
2010
119
30
89
0
0
0
0
58
78
92
PM2.5
2009
115
29
86
0
0
0
0
57
70
95
PM2.5
2008
285
80
205
0
0
0
0
57
74
93
PM2.5
2007
332
70
254
8
0
0
0
60
79
116
PM2.5
2006
122
28
92
2
0
0
0
58
78
127
PM2.5
2005
120
19
95
5
1
0
0
63
89
152
PM2.5
2004
120
29
90
1
0
0
0
59
82
109
PM2.5
2003
118
30
82
6
0
0
0
60
82
144
PM2.5
2002
114
23
88
3
0
0
0
60
81
126
PM2.5
2001
95
30
63
2
0
0
0
57
84
114
PM2.5
2000
117
15
96
6
0
0
0
64
82
133
PM2.5
1999
58
57
1
0
0
0
0
21
43
52
PM10
1998
58
58
0
0
0
0
0
24
42
47
PM10
1997
54
53
1
0
0
0
0
19
38
59
PM10
1996
55
55
0
0
0
0
0
21
37
50
PM10
1995
51
47
4
0
0
0
0
24
48
58
PM10
1994
49
48
1
0
0
0
0
28
46
77
PM10
1993
56
52
4
0
0
0
0
24
44
56
PM10
1992
56
52
4
0
0
0
0
26
44
55
PM10
1991
47
42
5
0
0
0
0
34
51
61
PM10
1990
47
40
7
0
0
0
0
31
54
65
PM10
1989
54
48
6
0
0
0
0
31
51
68
PM10
1988
59
50
9
0
0
0
0
29
57
73
PM10
1987
57
45
12
0
0
0
0
36
59
72
PM10
1986
55
47
8
0
0
0
0
38
54
78
PM10
1985
57
35
22
0
0
0
0
42
63
66
PM10
1984
40
32
8
0
0
0
0
36
68
83
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 Indiana with a similar median AQI in 2025
