Saint Mary's County, Maryland Air Quality

An Air Quality Alert is issued by the National Weather Service on behalf of a state or local agency when pollution is expected to reach a level that harms health. An Air Stagnation Advisory means the air will not move enough to clear what is already in it.

None are in force near Saint Mary's County right now. All Maryland warnings.

Good

Nearest monitor

Calvert, 23 miles away (site 240090011)

Index measured

19 · Good

Measured at

Sun, 6:00 PM EDT

Ozone

20 ppb

Reporting area

Southern Maryland, MD, 18 miles away

Reported by

Maryland Department of the Environment

Area index

20 · Good

Measured, not modeled. AirNow observations are preliminary until the operating agency certifies them, which happens months later.

Maryland Department of the Environment's own forecast for Southern Maryland, written by a forecaster rather than read off a model.

Written by Maryland Department of the Environment for Southern Maryland and filed with AirNow.

NOAA’s National Air Quality Forecast Capability, bias-corrected against monitors, for this town’s own coordinate. The worst hour ahead is an index of 43, Good, around Mon, 1:00 PM EDT, from the run issued Sun, 8:00 AM EDT. This is a model, not a measurement.

Fine particles in micrograms per cubic meter, ozone in parts per billion as an 8-hour average. The index for each hour is EPA’s: the ozone figure is already the 8-hour average the ozone index is defined on, and the particle figure is run through EPA’s NowCast, which is how an hourly PM2.5 concentration becomes an index.

NOAA’s analysts have not drawn smoke over Saint Mary's County in satellite imagery today.

NOAA’s model forecasts near-surface smoke peaking at 0.1 µg/m³ around Mon, 3:00 PM EDT.

Smoke on the radar over Saint Mary's County

Good

Air quality is satisfactory, and air pollution poses little or no risk.

Who is affected

Nobody is expected to be affected.

What to do

It is a good day to be outside.

Index range

0 to 50

Category descriptions are the Environmental Protection Agency’s own.

What these numbers are. An index beside a monitor’s name is a measurement, published hourly by AirNow and preliminary until the operating agency certifies it. A category for today or tomorrow is a state or local agency forecaster’s own forecast for a reporting area. An hourly index is NOAA’s air quality model on a five-kilometer grid, not a reading from any instrument. Where a town has no monitor within reach, only the model figures appear, and the page says so.

The nearest towns with a page of their own, closest first.

• Lexington Park, MD5 miles
• California, MD6 miles
• Leonardtown, MD8 miles
• Solomons, MD8 miles
• Drum Point, MD9 miles
• Chesapeake Ranch Estates, MD11 miles
• Lusby, MD11 miles
• Chesapeake Ranch Estates-Drum Point, MD11 miles

Observations and daily forecasts from AirNow, the US Environmental Protection Agency’s program with NOAA, the National Park Service, NASA, tribal, state and local agencies. Hourly forecasts from NOAA’s National Air Quality Forecast Capability. Smoke analysis from NOAA’s Hazard Mapping System. Alerts from the National Weather Service. Index categories and breakpoints are EPA’s, as revised in 2024.