Daily Air Quality Index summaries from EPA monitors in Allen, Ohio, 1980–2025.
67%
Good days in 2025
42
Median daily AQI, 2025
1
Days above 100 in 2025
351
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Allen, Ohio on 351 days. 235 of those days (67%) were in the Good range, and the median daily AQI was 42. That median is about the same as the typical monitored county in Ohio (median 43 across 36 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 204 days. Across the years with fuller monitoring, the share of Good days fell: an average of 83% in 1981–1983 versus 71% in 2023–2025.
Years with fewer than 120 monitored days (1980) 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)
204
58%
Ozone
147
42%
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
351
235
115
1
0
0
0
42
61
129
PM2.5
2024
359
275
84
0
0
0
0
42
58
97
Ozone
2023
365
252
105
5
3
0
0
44
67
194
PM2.5
2022
365
272
93
0
0
0
0
41
59
97
Ozone
2021
365
260
105
0
0
0
0
42
61
87
PM2.5
2020
360
289
70
1
0
0
0
40
57
105
Ozone
2019
332
229
103
0
0
0
0
44
61
97
Ozone
2018
356
260
91
5
0
0
0
42
61
119
Ozone
2017
365
298
66
1
0
0
0
38
57
112
Ozone
2016
366
297
66
3
0
0
0
37
58
122
Ozone
2015
365
288
76
1
0
0
0
38
58
105
PM2.5
2014
362
261
100
1
0
0
0
41
61
108
PM2.5
2013
362
268
92
2
0
0
0
40
61
112
PM2.5
2012
366
239
104
22
1
0
0
43
90
169
PM2.5
2011
364
246
109
9
0
0
0
41
74
119
PM2.5
2010
365
194
159
11
1
0
0
49
83
154
PM2.5
2009
232
189
39
4
0
0
0
41
67
105
Ozone
2008
239
196
42
1
0
0
0
42
67
105
Ozone
2007
237
158
61
17
1
0
0
44
97
156
Ozone
2006
240
176
55
8
1
0
0
43
80
161
Ozone
2005
238
147
68
21
2
0
0
44
100
159
Ozone
2004
235
185
45
5
0
0
0
41
74
129
Ozone
2003
225
153
57
11
4
0
0
44
90
195
Ozone
2002
232
149
48
24
11
0
0
45
122
200
Ozone
2001
231
164
55
11
1
0
0
43
80
159
Ozone
2000
235
183
45
4
3
0
0
42
74
177
Ozone
1999
234
150
48
29
7
0
0
45
119
192
Ozone
1998
237
129
67
35
6
0
0
49
119
182
Ozone
1997
235
166
47
20
2
0
0
42
100
161
Ozone
1996
231
148
51
26
6
0
0
45
108
200
Ozone
1995
232
151
48
26
7
0
0
46
112
192
Ozone
1994
238
140
59
32
7
0
0
45
119
177
Ozone
1993
237
154
59
20
4
0
0
44
101
166
Ozone
1992
217
160
40
15
2
0
0
41
87
174
Ozone
1991
200
109
60
22
9
0
0
49
119
182
Ozone
1990
208
150
40
16
2
0
0
41
100
161
Ozone
1989
211
136
56
15
4
0
0
45
93
174
Ozone
1988
203
143
33
22
4
1
0
39
112
202
Ozone
1987
212
139
41
29
3
0
0
44
112
195
Ozone
1986
272
243
26
3
0
0
0
31
51
112
Ozone
1985
302
233
54
13
2
0
0
37
87
156
Ozone
1984
299
256
33
10
0
0
0
33
64
143
Ozone
1983
311
229
47
31
4
0
0
34
105
195
Ozone
1982
289
260
16
11
2
0
0
32
54
159
Ozone
1981
139
118
15
6
0
0
0
31
67
147
Ozone
1980
31
31
0
0
0
0
0
15
24
28
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 Ohio with a similar median AQI in 2025
