Daily Air Quality Index summaries from EPA monitors in Jefferson, New York, 1986–2025.
95%
Good days in 2025
34
Median daily AQI, 2025
0
Days above 100 in 2025
355
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Jefferson, New York on 355 days. 336 of those days (95%) were in the Good range, and the median daily AQI was 34. That median is about the same as the typical monitored county in New York (median 36 across 27 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 355 days. Across the years with fuller monitoring, the share of Good days rose: an average of 68% in 1987–1989 versus 96% in 2023–2025.
Years with fewer than 120 monitored days (1986) 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
355
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
355
336
19
0
0
0
0
34
47
87
Ozone
2024
363
352
11
0
0
0
0
32
44
80
Ozone
2023
362
344
17
1
0
0
0
33
44
101
Ozone
2022
360
352
8
0
0
0
0
32
43
84
Ozone
2021
351
332
19
0
0
0
0
32
46
97
Ozone
2020
360
345
15
0
0
0
0
33
44
90
Ozone
2019
205
198
7
0
0
0
0
35
46
64
Ozone
2018
329
307
20
2
0
0
0
33
47
105
Ozone
2017
326
309
15
2
0
0
0
34
46
101
Ozone
2016
332
307
23
2
0
0
0
34
48
122
Ozone
2015
364
345
19
0
0
0
0
32
47
90
Ozone
2014
363
352
10
1
0
0
0
32
44
119
Ozone
2013
361
339
22
0
0
0
0
34
47
93
Ozone
2012
362
329
23
10
0
0
0
32
49
140
Ozone
2011
361
343
15
3
0
0
0
33
45
129
Ozone
2010
356
317
29
10
0
0
0
35
51
143
Ozone
2009
324
299
22
2
1
0
0
34
48
154
Ozone
2008
291
252
35
4
0
0
0
33
58
140
Ozone
2007
244
200
28
15
1
0
0
37
74
154
Ozone
2006
229
199
25
5
0
0
0
33
58
122
Ozone
2005
217
164
36
14
3
0
0
41
93
187
Ozone
2004
216
182
30
4
0
0
0
38
74
150
Ozone
2003
221
171
33
8
7
2
0
41
87
202
Ozone
2002
230
153
50
14
10
3
0
45
112
209
Ozone
2001
244
165
48
14
15
2
0
45
108
209
Ozone
2000
257
229
22
5
1
0
0
33
51
179
Ozone
1999
266
201
42
17
6
0
0
42
93
182
Ozone
1998
237
175
52
6
4
0
0
41
87
187
Ozone
1997
243
199
25
12
7
0
0
40
77
192
Ozone
1996
247
199
39
9
0
0
0
39
77
133
Ozone
1995
246
195
39
6
5
1
0
40
77
203
Ozone
1994
250
194
40
13
3
0
0
42
93
156
Ozone
1993
256
207
36
11
2
0
0
38
71
187
Ozone
1992
251
210
30
8
3
0
0
38
67
190
Ozone
1991
241
200
23
8
7
3
0
32
90
201
Ozone
1990
249
226
17
6
0
0
0
34
50
133
Ozone
1989
243
172
48
12
10
1
0
42
97
201
Ozone
1988
236
158
38
18
13
9
0
41
147
232
Ozone
1987
237
156
44
20
10
7
0
44
129
226
Ozone
1986
115
87
21
3
4
0
0
36
84
179
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 New York with a similar median AQI in 2025
