Daily Air Quality Index summaries from EPA monitors in Warren, New Jersey, 1980–2025.
78%
Good days in 2025
37
Median daily AQI, 2025
1
Days above 100 in 2025
360
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Warren, New Jersey on 360 days. 279 of those days (78%) were in the Good range, and the median daily AQI was 37. That median is lower than the typical monitored county in New Jersey (median 40 across 15 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 239 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 1980–2011 versus 75% in 2023–2025.
Years with fewer than 120 monitored days (2004, 2005, 2006, 2007, 2008, 2009…) 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
239
66%
Fine particles (PM2.5)
106
29%
Nitrogen dioxide (NO₂)
15
4%
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
360
279
80
1
0
0
0
37
61
105
Ozone
2024
357
284
71
2
0
0
0
36
56
108
Ozone
2023
361
241
114
1
5
0
0
41
61
197
PM2.5
2022
363
241
122
0
0
0
0
43
60
86
PM2.5
2021
358
237
120
1
0
0
0
42
61
136
PM2.5
2020
361
287
74
0
0
0
0
38
56
100
PM2.5
2019
364
279
84
1
0
0
0
39
57
103
PM2.5
2018
357
250
106
1
0
0
0
40
64
112
PM2.5
2017
364
253
110
1
0
0
0
42
60
101
PM2.5
2016
366
205
158
3
0
0
0
48
63
119
PM2.5
2015
363
298
64
1
0
0
0
35
58
115
Ozone
2014
365
309
56
0
0
0
0
37
55
92
Ozone
2013
365
264
99
2
0
0
0
39
62
115
PM2.5
2012
362
202
159
1
0
0
0
47
69
129
PM2.5
2011
362
199
159
3
1
0
0
47
69
154
PM2.5
2010
163
97
65
1
0
0
0
41
65
112
PM2.5
2009
117
75
42
0
0
0
0
41
64
86
PM2.5
2008
112
57
54
1
0
0
0
49
75
106
PM2.5
2007
108
41
66
1
0
0
0
55
83
125
PM2.5
2006
117
61
54
2
0
0
0
49
77
111
PM2.5
2005
117
43
72
2
0
0
0
56
80
124
PM2.5
2004
110
46
62
2
0
0
0
52
80
105
PM2.5
2003
110
47
61
1
1
0
0
54
82
156
PM2.5
2002
118
44
70
3
1
0
0
54
83
172
PM2.5
2001
103
40
61
2
0
0
0
55
83
111
PM2.5
2000
104
31
70
3
0
0
0
57
79
126
PM2.5
1999
24
9
15
0
0
0
0
54
72
92
PM2.5
1998
35
32
3
0
0
0
0
21
48
56
PM10
1997
56
55
1
0
0
0
0
19
41
65
PM10
1996
60
59
1
0
0
0
0
22
34
51
PM10
1995
60
58
2
0
0
0
0
20
42
60
PM10
1994
55
52
3
0
0
0
0
22
44
62
PM10
1993
57
54
3
0
0
0
0
24
41
59
PM10
1992
25
25
0
0
0
0
0
24
44
45
PM10
1982
32
31
1
0
0
0
0
23
44
78
CO
1981
90
54
36
0
0
0
0
42
81
99
NO2
1980
347
251
94
2
0
0
0
36
68
106
NO2
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 Jersey with a similar median AQI in 2025
