Northampton County, Pennsylvania air quality history
Daily Air Quality Index summaries from EPA monitors in Northampton, Pennsylvania, 1980–2025.
72%
Good days in 2025
38
Median daily AQI, 2025
2
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 Northampton, Pennsylvania on 365 days. 263 of those days (72%) were in the Good range, and the median daily AQI was 38. That median is about the same as the typical monitored county in Pennsylvania (median 40 across 38 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 212 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 1980–1982 versus 69% in 2023–2025.
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
212
58%
Fine particles (PM2.5)
148
41%
Nitrogen dioxide (NO₂)
5
1%
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
263
100
2
0
0
0
38
64
122
Ozone
2024
366
278
87
1
0
0
0
39
58
105
Ozone
2023
362
209
146
2
4
0
1
46
68
368
PM2.5
2022
358
224
132
2
0
0
0
45
64
118
PM2.5
2021
365
214
147
4
0
0
0
45
67
148
PM2.5
2020
365
260
104
1
0
0
0
41
59
117
PM2.5
2019
363
238
122
3
0
0
0
44
66
114
PM2.5
2018
365
194
166
5
0
0
0
48
77
136
PM2.5
2017
365
105
259
1
0
0
0
56
76
119
PM2.5
2016
366
153
203
9
0
1
0
53
77
242
PM2.5
2015
365
124
236
5
0
0
0
56
80
119
PM2.5
2014
365
148
214
3
0
0
0
53
74
118
PM2.5
2013
365
126
232
7
0
0
0
55
74
134
PM2.5
2012
366
99
253
13
1
0
0
57
82
151
PM2.5
2011
365
107
247
9
2
0
0
58
85
153
PM2.5
2010
365
112
229
22
2
0
0
58
90
172
PM2.5
2009
365
154
208
3
0
0
0
53
76
117
PM2.5
2008
366
143
208
14
1
0
0
55
80
172
PM2.5
2007
365
131
202
30
2
0
0
55
98
169
PM2.5
2006
365
158
189
15
3
0
0
54
85
185
PM2.5
2005
365
119
223
18
5
0
0
58
93
159
PM2.5
2004
366
115
223
24
4
0
0
57
93
200
PM2.5
2003
365
115
222
24
2
2
0
58
93
203
PM2.5
2002
365
123
199
26
16
1
0
57
112
201
PM2.5
2001
365
126
193
33
13
0
0
58
115
200
PM2.5
2000
366
152
187
22
3
2
0
54
93
212
PM2.5
1999
365
190
131
24
16
4
0
48
115
217
Ozone
1998
365
280
44
32
9
0
0
37
105
185
NO2
1997
290
215
49
17
9
0
0
39
100
192
Ozone
1996
312
223
57
26
6
0
0
44
101
192
Ozone
1995
362
259
64
23
13
3
0
42
108
207
NO2
1994
364
219
103
36
5
1
0
45
103
202
NO2
1993
365
279
47
35
4
0
0
40
101
197
NO2
1992
366
298
49
17
2
0
0
37
71
182
NO2
1991
365
264
67
21
10
3
0
40
100
208
NO2
1990
365
303
36
19
7
0
0
32
74
185
Ozone
1989
365
291
48
18
8
0
0
32
80
164
Ozone
1988
366
268
41
24
17
16
0
36
140
252
Ozone
1987
365
278
48
22
14
3
0
34
105
213
Ozone
1986
364
282
47
23
12
0
0
33
100
200
Ozone
1985
365
238
73
36
17
1
0
42
129
201
Ozone
1984
366
243
77
32
9
5
0
44
108
260
NO2
1983
365
240
60
28
24
13
0
42
151
225
NO2
1982
365
255
77
23
8
2
0
43
93
219
NO2
1981
358
212
117
21
8
0
0
45
93
192
NO2
1980
351
199
84
27
33
8
0
47
156
270
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 Pennsylvania with a similar median AQI in 2025
