Daily Air Quality Index summaries from EPA monitors in Sagadahoc, Maine, 1990–2025.
95%
Good days in 2025
35
Median daily AQI, 2025
1
Days above 100 in 2025
217
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Sagadahoc, Maine on 217 days. 207 of those days (95%) were in the Good range, and the median daily AQI was 35. That median is about the same as the typical monitored county in Maine (median 34 across 11 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 217 days. Across the years with fuller monitoring, the share of Good days rose: an average of 79% in 1991–1995 versus 94% in 2023–2025.
EPA did not report an AQI for every day of 2025 here (217 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.
Years with fewer than 120 monitored days (1990, 1993) 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
217
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
217
207
9
1
0
0
0
35
47
108
Ozone
2024
202
190
12
0
0
0
0
35
46
93
Ozone
2023
208
193
15
0
0
0
0
39
49
100
Ozone
2022
169
159
10
0
0
0
0
32
47
93
Ozone
2015
203
198
5
0
0
0
0
35
46
74
Ozone
2014
187
180
7
0
0
0
0
31
46
80
Ozone
2013
205
195
9
1
0
0
0
35
45
108
Ozone
2012
210
201
9
0
0
0
0
36
47
90
Ozone
2011
179
165
14
0
0
0
0
32
48
87
Ozone
2010
213
201
11
1
0
0
0
38
47
101
Ozone
2009
183
176
7
0
0
0
0
34
47
97
Ozone
2008
142
126
13
3
0
0
0
36
54
105
Ozone
2007
129
108
12
8
1
0
0
32
71
179
Ozone
2006
182
159
22
1
0
0
0
38
58
108
Ozone
2005
167
139
22
5
1
0
0
36
77
159
Ozone
2004
183
144
32
6
1
0
0
39
80
169
Ozone
2003
166
143
18
4
1
0
0
37
61
156
Ozone
2002
174
143
21
5
5
0
0
35
87
190
Ozone
2000
182
147
27
7
1
0
0
39
74
154
Ozone
1999
172
133
26
9
3
1
0
43
87
203
Ozone
1998
178
120
43
11
2
2
0
46
93
212
Ozone
1997
175
127
36
5
5
2
0
42
87
212
Ozone
1996
181
116
48
13
4
0
0
45
97
179
Ozone
1995
171
122
29
15
3
2
0
41
105
222
Ozone
1994
178
121
37
13
7
0
0
44
112
190
Ozone
1993
112
79
16
11
5
1
0
37
122
205
Ozone
1991
238
235
3
0
0
0
0
16
28
56
PM10
1990
105
105
0
0
0
0
0
13
27
38
PM10
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 Maine with a similar median AQI in 2025
