Maryland · AirNow reporting area

Maryland Piedmont, MD air quality

The Air Quality Index in Maryland Piedmont is 17 (Good) as of 4:00 AM EDT on Wed, Oct 28, with Ground-level ozone (O3) as the main pollutant. Today's forecast: AQI 55, Moderate (PM2.5). Tomorrow: AQI 55, Moderate (PM2.5). Preliminary data from the EPA AirNow program, reported by Maryland Department of the Environment.

Updated Oct 28, 2026, 4:11 AM EDT (snapshot)

Current AQI

AQI now

17Good

4:00 AM EDT, Wed, Oct 28

By pollutant

  • Ozone: 17Good

Yesterday's highest AQI

44Good

Ozone, Tue, Oct 27

What this AQI means for your health

Good (AQI 0–50). Air pollution is low and is not expected to affect health. A good day to be active outside.

These are general guidelines based on EPA's AQI categories, written in our own words. See the full AQI scale.

Air quality forecast

Daily AQI forecast issued by Maryland Department of the Environment. Some areas forecast a category without a number.

AQI forecast for Maryland Piedmont
DayForecastPollutants
Today, Wed, Oct 2855ModeratePM2.5 55
Tomorrow, Thu, Oct 2955ModeratePM2.5 55
Fri, Oct 3050GoodPM2.5 50

Monitor readings

Latest hourly NowCast AQI at 2 monitors assigned to or near this area. NowCast weighs recent hours more heavily so it reacts faster to changes. Distance is from the area's center point.

Monitors for Maryland Piedmont (hour starting, local time)
MonitorHourPM2.5 AQIOzone AQIPM10 AQIPM2.5 µg/m³Miles
Frederick Airport3 AM—3——5
South Carroll3 AM—17——15

Last 12 hours

Highest hourly NowCast AQI among the monitors above, for each hour (EDT).

Hourly AQI, highest monitor
Hour startingPM2.5 AQIOzone AQIPM10 AQIMonitors
3 AM—17—2
2 AM—16—2
1 AM—13—2
12 AM—14—2
11 PM—13—2
10 PM—16—2
9 PM—29—2
8 PM—28—2
7 PM—32—2
6 PM—37—2
5 PM—44—2
4 PM—45—2

Hourly monitor values from AirNow HourlyAQObs files, latest hour Oct 28, 2026, 3:00 AM EDT. Single-hour readings can be missing or revised.

Protecting yourself on bad air days

When the AQI is high, spend less time being active outdoors, keep windows closed if the outdoor air is worse than indoors, and run a portable HEPA air cleaner or your central system with a high-efficiency filter (MERV 13 or higher if your system can handle it). When fine particles or smoke are the problem, a well-fitted N95 respirator gives much better protection than a cloth or surgical mask. Read more on our wildfire smoke page.

Shopping for an air cleaner? Compare air purifiers on OpenPicks, our sister site.

Nearby areas

Hagerstown Region, MD

65Moderate

33 miles away

Suburban DC, MD

59Moderate

35 miles away

Martinsburg, WV

0Good

35 miles away

Northern Virginia, VA

59Moderate

40 miles away

Northern Virginia and DC, DC

57Moderate

42 miles away

Metro Baltimore, MD

43Good

43 miles away

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Sources

  • Current AQI, yesterday's maximum and forecasts: U.S. EPA AirNow reporting area file (files.airnowtech.org), as of Oct 28, 2026, 4:11 AM EDT.
  • Monitor readings: AirNow HourlyAQObs files (hourly NowCast AQI and raw concentrations).
  • Reporting agencies: Maryland Department of the Environment. These agencies own the data and are the authority for forecasts and advisories.
  • Values are shown as received from AirNow. See AirNow partners for the full list of agencies.

Preliminary data. AirNow readings and forecasts come from federal, state, local and tribal air quality agencies. They are not fully verified, may change, and must not be used for regulatory or official decisions; official data are in EPA's Air Quality System. For the latest official readings and advisories, check AirNow.gov and your state or local air agency.

This page is general information, not medical advice. If you have symptoms or a health condition, follow your doctor's guidance.

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