Air Quality Forecast

​​Air quality forecasts provided by the Maryland Department of the Environment (MDE) are available through a variety of online sources such as AirNow, Clean Air Partners, National Weather Service, and here on the MDE's website. Real-time air quality information can be found using these online sources in addition to the Current Air Quality Conditions Map. Air quality notifications can also be sent to your inbox by signing up for AirNow's EnviroFlash.  The Clean Air Partners and AirNow apps also deliver real-time air quality conditions and forecasts to your smartphone.

What actions should be taken when poor air quality episodes are forecasted? The Air Quality Action Guide can help you choose appropriate actions to reduce your exposure to air pollution and to actively participate in minimizing air pollution levels. Remember to do your share for cleaner air!

MDE offers 3-day air quality forecasts across ten Maryland regions. These forecasts are available year-round for fine particle pollution and during April - September for ground-level ozone pollution. Ozone can be a public health concern from late spring through the early fall months as a result of plenty of sunlight and hot temperatures. These air quality forecasts and discussions are prepared by MDE meteorologists in partnership with Metropolitan Washington Council of Governments (MWCOG), DC Department of Energy and Environment (DOEE), and Virginia Department of Environmental Quality (VADEQ).

The ten regions below each receive a forecast from MDE meteorologists for fine particles and/or ozone, depending on the time of year.  These regions were implemented in Spring of 2022.

Western Maryland Region (monitor: Piney Run)
This region represents Garrett and Allegany Counties in Western Maryland.  The higher elevations in this region have different air quality characteristics than the valley areas around Hagerstown.

Hagerstown Region (monitor: Hagerstown)
A distinct airshed exists from Hagerstown, MD to Winchester, VA along interstate I-81 and several small cities there-in.  The confined nature of the valley, with mountains on both sides, makes the valley susceptible to potential poor air quality under the right conditions, distinct from higher elevations adjacent to the valley.

Maryland Piedmont Region (monitors: Frederick, South Carroll)
This region is a transition from the higher terrain to the west and lower coastal plain to the southeast.  The region is typically representative of regional air quality and not typically susceptible to heavy urban plumes of pollution, making it distinct from other areas.

Northern Baltimore Region (monitor: Padonia)
The higher elevation north of Baltimore is above the coastal plain, making the region less susceptible to poor air quality than at the lower elevations except during the right meteorological conditions. With population density relatively lower in this region, poor air quality typically stems from long range transport from out of state and transport of the Baltimore pollution plume.

Northeast Maryland Region (monitors: Edgewood, Aldino, Fair Hill)
Northeastern Maryland is particularly susceptible to air quality issues related to Chesapeake Bay “Bay Breezes".  Air pollution from Baltimore or activity on the Bay may be pushed northeastward, impacting only this region and sparing others due to the localized meteorology (winds) of the Bay.

Metro Baltimore Region (monitors: Essex, Lake Montebello, Glen Burnie)
The Baltimore area has an abundance of air pollution sources due to industry, power plants, and greater population density in and around Baltimore City.  This region may be impacted by its own pollution during atmospheric stagnation, and from polluted “Bay Breezes".

Suburban DC Region (monitors: Rockville, HU-Beltsville, Beltsville CASTNET, Howard County Near-Road, PG Equestrian Center)
Typical surface flow is from the west and/or southwest, particularly in summer, making this semi-circle to the east of DC an area susceptible to air pollution from the greater DC and northern Virginia area.

*Howard County Near-Road measures fine particles but not ozone. 

Upper Eastern Shore Region (monitor: Millington)
The Upper Eastern Shore of Maryland occasionally finds itself in the plume of the I-95 corridor from Washington DC to Baltimore.  The Baltimore plume especially can hit this northern area under the right conditions, often avoiding the Lower Eastern Shore Region.

Lower Eastern Shore Region (monitors: Horn Point, Blackwater National Wildlife Refuge CASTNET)
With distinctly different meteorological and air pollutant influences than the Upper Eastern Shore, the Lower Eastern Shore has its own airshed, and its own forecast region.

Southern Maryland Region (monitors: Southern Maryland, Calvert)
Mostly rural and outside the DC pollution plume, air quality in Southern Maryland is unique and often much cleaner than other areas of the greater DC area.


Why Forecast for 10 Regions?

The scope and character of air quality events in Maryland has drastically evolved in the last two decades.  Air quality historically exceeding federal standards over large areas is now a rarity.  Instead, smaller areas experience infrequent exceedance events.   Maryland's investments in scientific research that precipitated this cleaner air now afford the ability to forecast localized areas of poor air quality.  An air quality forecast methodology that reflects the contemporary environment also better informs Maryland public health decisions.  Changing the forecast methodology better serves the citizens of Maryland.

Technology has also advanced over the last two decades.  Information technology and communication have undergone significant transformations.  Affordable small sensors and new satellites can identify localized air quality hot spots.  Changes to the MDE forecast protocol will keep MDE ahead of and embrace these developments. 

Finally, health protection is the primary purpose of air quality forecasting.  Contemporary events with ozone and/or fine particles exceeding the National Ambient Air Quality Standards (NAAQS) only occur at one or two, often adjacent monitors.  These circumstances do not justify broad poor air quality health alerts, and do not reflect regional contemporary changes in air quality.  Air quality alerts do not eliminate traffic jams, shut down industry or turn off HVAC.  The new forecast region format can detail where those activities may produce poor air quality.  These ten regions enable a health focused approach to air quality forecasting and will facilitate action on a personal level to protect health and wellbeing for all Maryland's citizens.

History of the Department's Air Quality Forecasting Program

In 2001, the Department of the Environment, Baltimore Metropolitan Council, and regional authorities MWCOG, VADEQ, and Washington DC Department of Health launched an air quality outreach website called "Air-Watch". Air-Watch provided the public with easy access to local and national air quality information by educating citizens about potential health risks related to air pollution. Furthermore, it strived to develop awareness and encourage public participation in finding solutions to air pollution. In 2007, Air-Watch became Clean Air Partners. For more history of the Department's Air Quality Forecasting Program, see the timeline provided below.



The Department of Environment revises Maryland forecast regions to ten, creating more precise and area specific forecasts.


EPA revises the ozone 8-hour average health-based National Ambient Air Quality Standard (NAAQS) and its AQI, effective December 2015.


EPA revises the particulate matter annual health-based NAAQS and the daily fine particle pollution AQI, effective March 2013.


The Department collaborates with local National Weather Service (NWS) offices of Baltimore/Washington, Philadelphia/Mount Holly, and Wakefield, VA to provide Air Quality Alerts on the NWS Map for Maryland and Metropolitan Washington when the Department forecasts poor air quality.

Air quality forecast discussions are now provided for the Metropolitan Baltimore, Western Maryland, and Eastern Shore regions.


The Department partners up with AirNow's EnviroFlash air quality notification program to increase dissemination of air quality forecasts and current air quality conditions to the public. Users can receive notifications via email or text message.

EPA revises the ozone health-based National Ambient Air Quality Standard (NAAQS) and its AQI, effective May 2008.


Air-Watch is combined and migrated into the improved Clean Air Partners website. Air quality forecasts, notifications, and air quality information are available through the Clean Air Partners website.


The Department expands the air quality forecasting program to the Eastern Shore. The 3-day air quality forecasts are now available state-wide and year-round for the 4 regions: Metropolitan Baltimore, Metropolitan Washington, Western Maryland, and Eastern Shore.


Air quality forecasting program expands operations to include 3-day air quality forecasts year-round. The Department also adds the Western Maryland region to the program. The 3-day air quality forecasts are now available for 3 regions: Metropolitan Baltimore, Metropolitan Washington, and Western Maryland. Additionally, forecast discussions are made available for the Metropolitan Baltimore region.


Summer ozone forecasting program expands to include year-round fine particle pollution and is renamed the Air Quality Forecasting Program. Daily air quality forecasts are now available year-round. Ozone Action Day is changed to Air Quality Action Day reflecting the multi-pollutant emphasis.

National Oceanic and Atmospheric Administration (NOAA) begins to provide operational air quality forecast model guidance. These guidance products are often used by many state and local agency air quality forecasters.


Regional authorities in the Baltimore and Washington DC metropolitan areas launch an air quality outreach website called "Air-Watch" to provide the public with easy access to air quality information, education about potential health risks related to air pollution, and to raise awareness while encouraging the public to actively participate in finding solutions to air pollution.


EPA adopts the color-coded forecasting method, originally developed by the Department and the American Lung Association, as part of the federal Air Quality Index (AQI) to present air quality information and forecasts to the public.


Pilot mapping for ground-level ozone gains national recognition. EPA starts a national ground-level ozone mapping program.


Ozone Action Day program begins through the ENDZONE partnership to promote voluntary actions to reduce air pollution and protect public health.


The Department takes on the primary role in air quality forecasting for Maryland. A regional collaboration is established between the Department, MWCOG, and VADEQ to expand the ozone forecasting program to include both the Baltimore and Washington DC metropolitan areas. Based on this regional collaboration, the "ENDZONE", for End Ozone, partnership is formed.

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