The Maryland Healthy Air Act

The Maryland Healthy Air Act (Annotated Code of Maryland Environment Title 2 Ambient Air Quality Control Subtitle 10 Health Air Act Sections 2-1001 - 2-1005) was developed with the purpose of bringing Maryland into attainment with the National Ambient Air Quality Standards (NAAQS) for ozone and fine particulate matter by the federal deadline of 2010.  The act and the subsequent regulations also requires the reduction of mercury emissions from coal-fired electric generating units and significantly reduces atmospheric deposition of nitrogen to the Chesapeake Bay and other waters of the State. 

The Healthy Air Act is the toughest power plant emission law on the east coast.  The HAA requires reductions in nitrogen oxide (NOx), sulfur dioxide (SO2), and mercury emissions from large coal burning power plants.  The Healthy Air Act also requires that Maryland become involved in the Regional Greenhouse Gas Initiative (RGGI) which is aimed at reducing greenhouse gas emissions.

NOx is the most important pollutant contributing to Maryland’s ground-level ozone or “smog” problem and also contributes significantly to nitrogen pollution in the Chesapeake Bay. SO2 is the most important contributor to Maryland’s fine particulate air pollution problem and also has a significant role in creating regional haze that degrades visibility.

The Maryland Department of the Environment (MDE) is charged with implementing the HAA through regulations. The HAA regulations constitute the most sweeping air pollution emission reduction measure in Maryland history.  The HAA regulations became effective on July 16, 2007. 

Overview of Expected Emission Reductions

Over 95 percent of the air pollution emitted from Maryland’s power plants comes from the largest and oldest coal burning plants.  The emission reductions from the Healthy Air Act come in two phases.  The first phase requires reductions in the 2009/2010 timeframe and, compared to a 2002 emissions baseline, reduce NOx emissions by almost 70%, SO2 emissions by 80%, and mercury emissions by 80%.

The second phase of emission controls occurs in the 2012/ 2013 timeframe.  At full implementation, the HAA will reduce NOx emissions by approximately 75% from 2002 levels, SO2 emissions will be reduced by approximately 85% from 2002 levels, and mercury emissions will be reduced by 90%.

Frequently Asked Questions

What’s the solution to cut air pollution in Maryland?
The Maryland Healthy Air Act is the most sweeping air quality law in Maryland history.  Under this law, Maryland is indeed doing our part locally to meet national health-based standards for ozone and fine particulate by the 2010 deadline.  The Healthy Air Act also protects the Chesapeake Bay by reducing nitrogen and mercury pollution from the air. Additionally, the Act helps to improve visibility throughout scenic areas in Maryland and other states.  

Which emission sources are affected by the rule?
The Healthy Air Act impacts Maryland’s largest coal-burning power plants, which account for over 95% of the state’s power plant emissions. Facilities covered include: Constellation Energy Group’s Brandon Shores, Crane, and Wagner plants; Mirant Corporation’s Chalk Point, Morgantown and Dickerson plants: and the R Paul Smith Plant located in Washington County, Maryland.

Which pollutants are covered by this rule and how much pollution will be reduced?
The Healthy Air Act requires year-round emission controls that will significantly reduce nitrogen oxides (NOx), sulfur dioxide (SO2), and mercury from power plants located in Maryland. NOx emissions in Maryland will be reduced almost 70% in 2009. A second phase of NOx control will reduce emissions by a total of 75% by 2012.

 SO2 emissions will be reduced by 80% in 2010 with a second phase of controls in 2013, which will increase the emission reduction to 85%. When the rule is adopted, mercury emissions will be reduced by 80% in 2010. A second phase of controls will reduce mercury emissions by 90% by 2013.  All of the above emission reductions are based on a comparison to a 2002 emissions baseline.

How does the Healthy Air Act compare to the federal Clean Air Rule?
The Maryland Healthy Air Act will provide larger reductions in NOx, SO2 and mercury in a faster timeframe than the federal Clean Air Interstate Rule (CAIR) and Clean Air Mercury Rule (CAMR). The Maryland Healthy Air Act prohibits Maryland power plants from acquiring out-of-state emissions allowances (trading credits) in lieu of adding pollution controls locally. This means cleaner air in Maryland.

Does the rule bring Maryland closer to meeting federal air quality standards?
The Maryland Healthy Air Act is the cornerstone of Maryland’s plan to meet the 1997 federal ozone and fine particle standards. Local emission reductions from the Healthy Air Act will provide more than 90% of the reductions needed in Maryland to comply with the 2010 ozone and fine particle standards. Maryland is working with the Ozone Transport Commission on a suite of emission control measures to achieve the remaining 10%.

What is Maryland doing to address pollution in upwind states?
The Ozone Transport Commission (OTC) Multi-Pollutant Workgroup, chaired by Maryland, has been working over the past several years to develop a regional power plant control program that is more aggressive than the federal approach because EPA's analysis of CAIR shows that Maryland, as well as several other states, will not comply with the new ozone standard with CAIR alone.  This effort has expanded to include states beyond the Ozone Transport Region including the Midwest and Texas, through a multi-state collaborative process.

Clean Power Rule PosterHow does the Healthy Air Act benefit the Chesapeake Bay?
More than one-third of the pollution entering the Chesapeake Bay comes from the air. Pollutants released into the air (primarily from power plants and vehicle emissions) eventually make their way back down to the earth’s surface and are dispersed onto the land and transported into waterways. The emission controls on power plants will reduce nitrogen entering the Bay by up to 900,000 pounds each year and will reduce mercury significantly.

Why do we need to reduce NOx and SO2?
SO2 and NOx contribute to the formation of fine particles and NOx contributes to the formation of ground-level ozone. Fine particles and ground-level ozone are associated with thousands of premature deaths and illnesses nationally each year. In Maryland alone, as many as 390 premature deaths are anticipated each year as a result of fine particles and ground-level ozone. Additionally, these pollutants reduce visibility and damage sensitive ecosystems.

What are the adverse health effects of long-term exposure to fine particulates and ozone?
Adverse health effects that relate to both fine particles and ozone include emergency room visits, hospital admissions, and restricted activity days. Adverse health effects associated specifically with ozone include decreased lung function, asthma attacks, and throat and eye irritation. Excess fine particles can cause premature mortality, heart attacks, upper and lower respiratory symptoms, and asthma exacerbations.

Where can I find more information about air quality in Maryland?
The quality of our local air affects the way we live and breathe. Millions of people live in areas where ground level ozone, very small particles, and toxic pollutants pose serious health concerns. Visit our Air and Radiological Health Information Center to learn more about how MDE ensures the air is safe to breathe for all who live in and visit Maryland.


Contact Information

For additional information on Maryland's Healthy Air Act, please call 410-537-3245.​


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