Daily Air Quality Index summaries from EPA monitors in Baltimore (City), Maryland, 1980–2025.
68%
Good days in 2025
43
Median daily AQI, 2025
2
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Baltimore (City), Maryland on 364 days. 248 of those days (68%) were in the Good range, and the median daily AQI was 43. That median is higher than the typical monitored county in Maryland (median 39.5 across 16 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 191 days. Across the years with fuller monitoring, the share of Good days rose: an average of 26% in 1980–1982 versus 68% 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
Fine particles (PM2.5)
191
52%
Ozone
162
45%
Nitrogen dioxide (NO₂)
11
3%
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
364
248
114
2
0
0
0
43
64
136
PM2.5
2024
365
258
101
6
0
0
0
42
67
112
Ozone
2023
365
242
116
4
3
0
0
44
71
192
PM2.5
2022
353
242
109
2
0
0
0
44
64
112
Ozone
2021
364
243
121
0
0
0
0
43
61
93
PM2.5
2020
363
293
70
0
0
0
0
38
56
97
PM2.5
2019
363
217
140
6
0
0
0
46
65
126
PM2.5
2018
364
182
174
8
0
0
0
51
74
129
PM2.5
2017
365
221
141
3
0
0
0
46
62
112
PM2.5
2016
366
192
168
5
1
0
0
49
73
156
PM2.5
2015
365
159
200
6
0
0
0
53
76
140
PM2.5
2014
365
146
219
0
0
0
0
52
68
95
PM2.5
2013
365
150
214
1
0
0
0
52
70
108
PM2.5
2012
366
126
235
4
1
0
0
55
77
154
PM2.5
2011
365
111
240
13
1
0
0
56
79
154
PM2.5
2010
365
129
225
10
1
0
0
55
79
187
PM2.5
2009
365
118
242
5
0
0
0
55
74
111
PM2.5
2008
366
107
255
4
0
0
0
58
78
140
PM2.5
2007
365
79
273
13
0
0
0
59
82
150
PM2.5
2006
365
86
265
14
0
0
0
59
87
150
PM2.5
2005
365
27
321
17
0
0
0
65
90
136
PM2.5
2004
366
38
310
18
0
0
0
63
91
128
PM2.5
2003
365
61
281
22
1
0
0
62
91
156
PM2.5
2002
365
56
276
22
10
1
0
63
98
213
PM2.5
2001
365
73
262
24
6
0
0
64
94
172
PM2.5
2000
365
107
237
19
2
0
0
61
90
159
PM2.5
1999
365
232
104
22
7
0
0
42
96
197
NO2
1998
365
265
81
14
5
0
0
39
80
177
NO2
1997
365
262
64
24
11
4
0
42
101
215
NO2
1996
366
270
71
19
6
0
0
42
90
174
NO2
1995
365
261
56
26
16
6
0
40
112
221
NO2
1994
365
242
108
11
3
1
0
44
80
203
NO2
1993
365
197
142
21
5
0
0
48
87
172
NO2
1992
366
224
128
14
0
0
0
47
74
150
NO2
1991
362
172
149
33
7
1
0
51
105
207
NO2
1990
365
185
130
35
14
1
0
50
112
226
NO2
1989
365
179
164
18
4
0
0
51
83
190
NO2
1988
366
145
161
31
15
14
0
55
136
251
NO2
1987
365
120
238
6
1
0
0
57
85
190
NO2
1986
365
97
226
30
11
1
0
62
102
212
NO2
1985
365
71
257
30
7
0
0
68
101
187
NO2
1984
366
82
221
49
12
2
0
66
122
206
CO
1983
350
77
216
33
19
5
0
67
125
227
CO
1982
356
100
203
45
7
1
0
68
109
202
CO
1981
365
72
240
44
7
2
0
70
108
205
CO
1980
364
114
162
59
21
8
0
69
129
234
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 Maryland with a similar median AQI in 2025
