Daily Air Quality Index summaries from EPA monitors in Kent, Delaware, 1980–2025.
76%
Good days in 2025
41
Median daily AQI, 2025
4
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 Kent, Delaware on 365 days. 276 of those days (76%) were in the Good range, and the median daily AQI was 41. That median is about the same as the typical monitored county in Delaware (median 41 across 3 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 229 days. Across the years with fuller monitoring, the share of Good days fell: an average of 80% in 1980–1983 versus 71% in 2023–2025.
Years with fewer than 120 monitored days (1981) 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
229
63%
Fine particles (PM2.5)
136
37%
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
276
85
4
0
0
0
41
62
122
Ozone
2024
336
250
86
0
0
0
0
41
58
100
Ozone
2023
348
216
124
5
2
1
0
46
64
207
PM2.5
2022
364
277
87
0
0
0
0
42
58
84
PM2.5
2021
360
260
98
2
0
0
0
42
58
108
Ozone
2020
362
296
66
0
0
0
0
39
54
80
Ozone
2019
365
248
117
0
0
0
0
44
61
85
Ozone
2018
365
267
96
2
0
0
0
42
59
133
Ozone
2017
361
264
96
1
0
0
0
42
59
101
Ozone
2016
364
272
90
2
0
0
0
42
63
136
Ozone
2015
365
245
120
0
0
0
0
44
64
100
Ozone
2014
364
230
133
1
0
0
0
46
62
108
PM2.5
2013
357
221
136
0
0
0
0
46
63
100
PM2.5
2012
342
209
112
17
4
0
0
44
80
182
Ozone
2011
365
270
90
3
2
0
0
41
65
172
Ozone
2010
307
193
102
9
3
0
0
44
84
166
Ozone
2009
262
174
88
0
0
0
0
44
67
97
Ozone
2008
268
130
121
17
0
0
0
51
87
147
Ozone
2007
262
133
117
12
0
0
0
50
90
129
Ozone
2006
265
129
120
13
3
0
0
51
90
159
Ozone
2005
265
131
112
20
2
0
0
51
97
154
Ozone
2004
263
143
107
13
0
0
0
49
87
147
Ozone
2003
274
154
102
15
3
0
0
48
93
197
Ozone
2002
281
124
119
26
12
0
0
54
112
192
Ozone
2001
277
127
123
19
7
1
0
52
100
204
Ozone
2000
269
135
115
14
3
2
0
50
90
205
Ozone
1999
266
125
100
29
11
1
0
53
126
205
Ozone
1998
238
127
61
34
16
0
0
50
140
200
Ozone
1997
220
135
51
22
10
2
0
45
126
218
Ozone
1996
202
120
52
22
8
0
0
46
119
179
Ozone
1995
192
111
51
23
5
2
0
47
115
213
Ozone
1994
213
128
59
21
5
0
0
47
105
179
Ozone
1993
237
148
55
26
8
0
0
43
122
195
Ozone
1992
175
161
12
2
0
0
0
34
48
133
Ozone
1991
149
111
26
11
1
0
0
40
93
159
Ozone
1990
195
145
37
10
3
0
0
39
80
172
Ozone
1989
184
91
52
26
14
1
0
51
140
201
Ozone
1988
201
107
38
24
18
14
0
48
182
244
Ozone
1987
291
192
48
30
18
3
0
39
136
208
Ozone
1986
273
194
41
28
10
0
0
38
108
195
Ozone
1985
336
218
67
36
14
1
0
40
122
216
Ozone
1984
317
211
55
32
14
5
0
40
133
212
Ozone
1983
276
169
51
30
18
8
0
43
140
223
Ozone
1982
215
209
6
0
0
0
0
19
33
93
Ozone
1981
89
86
0
1
2
0
0
9
28
200
Ozone
1980
202
162
17
10
13
0
0
24
108
190
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 Delaware with a similar median AQI in 2025
