Air Quality Rankings for Maryland 2026

Maryland has 16 cities with EPA air quality data. Howard, Maryland has the cleanest air with a 5-year average AQI of 37. Baltimore, Maryland has the highest AQI at 45.

#	City	5yr Avg AQI	Current AQI	Worst Pollutant	Trend	Grade
1	Howard, Maryland	37	38	PM2.5	Improving	B
2	Garrett, Maryland	39	40	Ozone	Improving	B
3	Calvert, Maryland	39	42	Ozone	Improving	B
4	Charles, Maryland	39	42	Ozone	Improving	B
5	Kent, Maryland	40	41	Ozone	Improving	B
6	Anne Arundel, Maryland	40	40	Ozone	Improving	B
7	Montgomery, Maryland	41	42	PM2.5	Improving	B
8	Dorchester, Maryland	41	44	Ozone	Improving	B
9	Prince George's, Maryland	42	44	Ozone	Improving	B
10	Washington, Maryland	42	42	PM2.5	Improving	B
11	Carroll, Maryland	42	44	Ozone	Stable	B
12	Cecil, Maryland	42	42	PM2.5	Improving	B
13	Frederick, Maryland	42	44	Ozone	Stable	B
14	Baltimore (City), Maryland	43	44	PM2.5	Improving	B
15	Harford, Maryland	44	45	PM2.5	Improving	B
16	Baltimore, Maryland	45	45	Ozone	Stable	C

Air quality data for Maryland is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
— EPA Air Quality System

Frequently Asked Questions

Howard, Maryland has the best air quality in Maryland with a 5-year average AQI of 37 and a grade of B.

Maryland has 16 cities with EPA air quality monitoring data in our database, covering multiple years of AQI measurements.

The Air Quality Index (AQI) measures five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Lower AQI values indicate cleaner air — 0-50 is "Good," while 150+ is "Unhealthy."

Sources: EPA Air Quality System (AQS)

Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.

Cleanest Cities Nationwide →All Air Quality in Maryland →