The United States reports air quality using a measure called the Air Quality Index. The AQI runs from zero to 500, with higher numbers indicating more air pollution — thus presenting a more significant health concern. Generally speaking, an AQI value below 50 represents good air quality, and air quality becomes hazardous when the AQI tops 300. However, anything below 100 is typically satisfactory.
AQI values fall into six color-coded categories.
If you want to stay up to date on air pollution in Maryland, you have a couple of options. You can check Maryland’s Department of the Environment to get real-time updates or check the weather app on your smartphone.
What Contributes to Air Quality?
Many variables affect a region’s air quality, including the following.
- Popular local industries: Cities with businesses that create more pollution, such as power plants or factories, may have worse air quality than more rural areas.
- Population density: Population density also influences a location’s air quality. More people means more human-induced pollution, resulting from things like vehicle emissions, tobacco smoke, candle and fireplace emissions, non-energy-saving appliances, non-HEPA air filters and electricity use.
- Geography: An area’s physical location affects its air quality. For instance, areas that get a lot of sunlight can result in the development of smog, and arid cities that don’t get much rain do not benefit from its capability to wash away pollutants. That’s why Los Angeles consistently has one of the highest AQIs in the United States.
Ranking the Best Maryland Counties by Air Quality
The American Lung Association creates report cards to display air quality and pollution in the United States. In these “State of the Air” reports, they assign each county in a specific state a letter grade depending on how often they experienced high-ozone days over three years. The most recent data collected was between 2018 and 2020.
The following counties boast some of the best air quality in Maryland, receiving letter grades of A or B.
- Garrett: Garrett County received an A on its air quality report card. Garrett County did not experience any high-ozone days between 2018 and 2020. Cities in this county include Friendsville, Oakland, Grantville and Accident.
- Washington: Washington County — not Washington, D.C. — was the only other Maryland county to receive an A on its State of the Air report. Cities in Washington County include Hagerstown, Williamsport, Sharpsburg and Smithsburg.
- Calvert: Calvert County received a B on the American Lung Association report card. Calvert County had one orange ozone day during the reporting period. This region is primarily rural, and the air is often much cleaner than the other areas surrounding D.C.
- Charles: Like Calvert, the cities in Charles County received a B on the State of the Air report. Some cities in Charles County include La Plata, Waldorf and Saint Charles.
- Frederick: The Frederick and South Carroll areas mark a transition from Maryland’s higher terrain of the west to the lower coastal plain of the southeast. This area is not typically susceptible to the plumes of pollution that are relatively common in urban areas, and its lower score reflects that.
- Montgomery: South of Frederick, Montgomery County experienced few orange ozone days during the research period. Montgomery County is home to over 1 million people, showing that densely populated areas do not inherently have unhealthy air quality.
What Maryland Counties Have the Unhealthiest Air Quality?
While Maryland’s ozone pollution levels have improved significantly since 2004, some areas still experience unhealthy air quality.
Many of the counties that experience the unhealthiest air quality in Maryland — including Harford, Cecil and Anne Arundel — are near Baltimore and Baltimore City. Here is some more information regarding how the American Lung Association classifies these areas.
- Prince George’s: Prince George’s County is right outside Washington, D.C., possibly contributing to higher unhealthy air quality levels. Prince George’s County averages 5.2 high-ozone days per year.
- Harford: East of Baltimore County, Harford County recorded 20 orange ozone days during the research period. Its F score also comes from a higher annual weighted average number of high-ozone days, at 6.7 per year.
- Cecil: East of Harford, Cecil County experienced a weighted average of 3.3 high-ozone days per year between 2018 and 2020. The county also faced 10 orange ozone days in the same period.
- Anne Arundel: South of Baltimore City County, Anne Arundel County recorded 14 orange ozone days and one red. Its annual weighted average of high-ozone days is 5.2 per year, based on the research.
- Baltimore: Baltimore County and Baltimore City County received an F on the State of the Air Report Card for 2018 and 2020. On average, Baltimore County experienced 5.0 high-ozone days per year, with 15 orange ozone days.
- Baltimore City: The metro Baltimore area is more susceptible to air pollution because of its population density and nearby power plants. Baltimore City County’s average high-ozone days were lower than Baltimore County’s, at 4.3 days annually between 2018 and 2022. The county also faced 13 orange ozone days in the same period.
- Washington, D.C.: Though not technically a Maryland county, Washington, D.C., is still a significant part of the state! The District of Columbia received an F on the State of the Air report, with nine orange days and one red day during the reporting period.
Indoor Air Quality Services Can Improve the Air Quality in Your Home
While taking environmentally friendly steps outside your home — like sharing transportation — can help improve outdoor air quality, you may be wondering the best steps you can take to improve the air quality inside your home, too.
Dust, pollen, mildew, bacteria and mold are present in almost every home and can adversely affect your family’s health. If this concerns you, the experts at Metro Services HVAC can help! We offer the following affordable, outstanding solutions to help improve your indoor air quality:
- Duct cleaning
- Humidifiers and dehumidifiers
- Air filters
- Electronic air cleaners and air purifiers
If you’re ready to improve your home’s IAQ, request your estimate today! Our team is excited to provide you with the air quality solutions to make your home a better place to live in.