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On many summer nights, smog blowing in from other states collects high above sleeping Marylanders. Day breaks and the sun warms the air. Pollution that originated hundreds of miles upwind then mixes downward, combines with local pollution and degrades the air we breathe.
It’s the chain of events that leads to almost all of Maryland's unhealthy air days – but MDE is working hard to address the problem.
While the amount of air pollution generated locally has dropped dramatically, as much as 70 percent of Maryland’s pollution comes from upwind states. MDE makes it a priority to work with its counterparts from other Mid-Atlantic and Northeast states to find ways to further improve our air quality by reducing pollution from halfway across the country.
MDE has worked since the 1990s with a multi-state organization known as the Ozone Transport Commission (OTC) on regional air pollution issues. This organization is now weighing options that include encouraging tougher federal emission control standards and, in the case of some states, taking legal actions to require other states to be “good neighbors.” Both OTC and the National Association of Clean Air Agencies have passed resolutions asking the U.S. Environmental Protection Agency to adopt various categories of national control measures.
“The State of Maryland has adopted the toughest power plant and mobile source control programs in the East. We send up airplanes and balloons to measure pollution coming into the State that already violates air quality standards,” said Tad Aburn, Director of MDE's Air and Radiation Management Administration. “We need to up the ante on the air pollution transport issue to protect the health of Maryland’s citizens.”
Reducing Maryland’s air pollution
Maryland recognizes that it is important to address locally-generated air pollution before asking other states to reduce pollution that travels to Maryland. To that end, MDE has since 1990 adopted more than 100 regulations designed to reduce emissions from diverse sources including electricity generating plants, commercial printers and waste incinerators, as well as consumer products such as perfume and hair dye.
The State also passed critical legislation, such as the Maryland Healthy Air Act in 2006 and the Clean Cars Act in 2007. The Clean Cars Program requires more stringent standards for new vehicles and dramatically reduces emissions of pollutants that create unhealthy air and changes in our climate.
In response to the requirements of the Healthy Air Act, Maryland electricity generators have invested $2.6 billion in control technologies. The Healthy Air Act is the toughest power plant emission law on the East Coast and has already slashed emissions of nitrogen oxide, sulfur dioxide and mercury and helped improve air quality and the health of the Chesapeake Bay.
Last month, MDE released the Clean Air Progress in Maryland report. That report includes information on the dramatic improvement in air quality in recent years – and the need to address the transport issue.
How pollution is transported
Air pollution can travel vast distances quickly, depending on factors such as wind and weather patterns. Consider that an air monitoring station in Harford County – hundreds of miles from the Midwest and several miles from major emissions sources in Maryland – consistently records some of the highest levels of air pollution in Maryland.
There are generally three paths by which air pollution is transported into Maryland. Long-range transport typically originates in the Midwest and travels hundreds of miles on upper air wind currents. Mid-range night-time transport originates south of Maryland and travels tens to hundreds of miles on upper air wind currents. Local transport is characterized by movement between urban areas like Washington to Baltimore to Philadelphia on surface winds.
Some air pollution is transported eastward on upper air wind currents at night. Emissions from sources in distant states may be carried by a fast-moving, narrow “river” of air, typically about 1,000 feet above the surface for hundreds of miles in a single night. This pollution slowly mixes down to surface in the morning. As the transported pollution combines with the pollution generated locally, it affects that day’s air quality. A portion will form the aloft “ozone reservoir” and be a part of the next night’s transported pollution stream. The Chesapeake Bay breeze can either keep pollution over land or take pollution transported on southerly winds over the bay and direct it towards the land.
At the end of the day – particularly a hot summer one – air quality and public health are adversely affected by the interplay of pollution, weather and wind patterns. Ozone and fine particles affect the health and welfare of people and the environment across a broad region. To better protect the public health, the U.S. Environmental Protection Agency strengthened the ozone standard in 2008.
The new ozone standard
In implementing the new ozone standard, EPA designates areas as attainment (complying with the standard) or nonattainment (not complying with the standard to varying degrees) based on monitored data. Based on data from the monitor in Harford County, the Baltimore area is the lone “moderate” nonattainment area in the east.
Other large eastern cities such as Philadelphia and New York have been designated as “marginal” nonattainment areas – even though Baltimore’s locally generated air pollution is lower than in those cities. As a result of these designations, sources in the Baltimore region would be required to implement significant emissions controls at a high cost to Maryland sources, while sources in other metropolitan areas would be required to implement few if any controls.
The moderate nonattainment status puts Baltimore at an economic disadvantage. Addressing pollution regionally is important for public health and creates more of a "level playing field" economically. Research conducted by MDE, the University of Maryland, University of Maryland Baltimore County and Howard University supports the concept of air pollution transport and the need for additional national or super-regional control programs to reduce emissions and attain the new ozone standard.
Across the east, numerous control programs must be implemented, ranging from further emissions reductions from power plants, to control measures for paints and other consumer products. MDE is committed to protecting health and the environment by continuing to adopt aggressive local controls and advocating for enhanced regional programs.
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