Maryland and seven other Northeast and Mid-Atlantic states have filed a petition asking the U.S. Environmental Protection Agency (EPA) to add nine upwind states to the Ozone Transport Region (OTR). If added to the Ozone Transport Region, those states would be required to take additional steps to reduce air pollution that has been found to significantly affect downwind states.

States filing the petition – all current members of the OTR – are:  Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont.

The petition It seeks to add Illinois, Indiana, Kentucky, Michigan, North Carolina, Ohio, Tennessee, Virginia and West Virginia to the Ozone Transport Region.


In May, the downwind states wrote letters to environmental officials in those nine upwind states asking them to voluntarily join the Ozone Transport Region. Officials in those states indicated a willingness to work with downwind states on technical matters relating to reducing air pollution, but no state voluntarily agreed to join the OTR.

The petition was filed as authorized by Section 176A of the federal Clean Air Act.  Section 176A permits a Governor of a State to petition the EPA Administrator to add any State or portion of a State to any air quality region established under the Clean Air Act if there is reason to believe that interstate transport significantly contributes to a violation of a National Ambient Air Quality Standard for ozone in the transport region.


The Section requires the EPA Administrator to approve or disapprove a petition within 18 months of receipt. The petition includes a request from the States that the Administrator provide an opportunity for public participation, including public notice and comment, on the petition.


States added as members of the OTR would be required to take additional steps to reduce air pollution that has been found to significantly affect downwind states. These steps can include:

  • Implementation of Reasonably Available Control Technology for stationary emissions sources. Under this requirement, State regulators require sources to meet emissions limits developed by the application of controls that are reasonably available considering current technologies and cost.
  • Broadened application of preconstruction permit application reviews under the New Source Review program, which is designed to ensure that new major sources and modifications to major sources do not slow progress toward cleaner air.
  • Inspection and maintenance programs to reduce vehicle emissions by ensuring vehicles are in good repair.


Ozone is a gas that occurs in two layers of the atmosphere. When ozone is up very high in the atmosphere it is considered “good” as it protects us from the sun’s ultra-violet rays, however when ozone occurs near ground level it is harmful to human health and our environment. Nitrogen oxides are emitted when fossil fuels are burned. Nitrogen oxides combine with volatile organic compounds to form ground-level ozone when heated by the sun.


To improve public health protection, EPA revised its primary 8-hour ozone standard from 85 parts per billion (ppb) to 75 ppb. In announcing the revision, EPA stated that the Agency estimates that the revised standards will yield health benefits valued between $2 billion and $17 billion, adding that those benefits include preventing cases of bronchitis, aggravated asthma, hospital and emergency room visits, nonfatal heart attacks and premature death, among others.


To meet the attainment deadline for the Baltimore area, which records some of the worst air quality in the eastern half of the United States, air quality must improve by 2016.



Despite gains made by Maryland to reduce air pollution from in-state sources, the State will be unable to meet the revised ozone standard unless pollution from upwind states is reduced.


  • At times, up to 70 percent of Maryland’s air pollution is due to out-of-state sources.
  • EPA modeling shows that in the Baltimore area, 49 percent of the “design value,” the calculation used to determine attainment of air quality standards, is attributable to ozone transport.
  • More than 15 years of aircraft measurements by the University of Maryland have proven that aloft air coming into Maryland contains ozone concentrations between 60 ppb and 100 ppb as the result of sources in nearby states.
  • Ozone concentrations well above the revised standard of 75 ppb have been measured repeatedly over the western boundaries of Maryland, which are upwind of the rest of the State.


The Maryland Healthy Air Act requires the State’s largest coal-burning power plants to reduce emissions of nitrogen oxide (the principal contributor to Maryland’s ozone problem and a source of nitrogen pollution to the Chesapeake Bay and local waterways), sulfur dioxide (the principal contributor to fine particulate pollution in Maryland) and mercury, a toxic metal.

The Healthy Air Act produces emissions reductions in two phases. The first phase, which occurred in the 2009-2010 timeframe, reduced emissions of nitrogen oxides by almost 70 percent and sulfur dioxide and mercury emissions by 80 percent. Those requirements are being met. In the second phase, beyond 2012, additional reductions will occur so that reductions of nitrogen oxides emissions will total about 75 percent, reductions of sulfur dioxide emissions will total 85 percent and reductions in mercury emissions will total 90 percent.


To accomplish these reductions and meet the requirements of the Healthy Air Act, Maryland utilities have invested approximately $2.6 billion in such pollution controls as state-of-the-art “scrubbers” that remove sulfur from coal-burning gases and technology that removes nitrogen oxides from smoke stacks.



The petition is one of several legal actions taken by states plagued by ozone pollution from upwind states.

These actions include support for a request for Supreme Court review of a case involving air pollution from power plants. In 2012, the U.S. Court of Appeals issued a ruling that vacated the EPA’s Cross-State Air Pollution Rule, which addresses air pollution from power plants that contributes to unhealthy air in downwind states. Maryland Department of the Environment Secretary Robert M. Summers said then that the ruling dealt a “significant blow to our ongoing efforts to improve the quality of our air in Maryland.”

Maryland supported a petition by EPA and environmental groups for the Supreme Court to review that decision – and in June the Court said that it would review the case.

Other legal steps include actions to enlarge nonattainment areas (areas that do not comply with federal air quality standards). Some downwind states have recommended to EPA that nonattainment areas not only include the area that violates the standard but also the area that causes the violation. This expands the geographic areas in which controls are applied and generally reduces control costs. EPA continues to minimize the size of nonattainment areas.

The Clean Air Act contains a “good neighbor” provision. It requires states to examine whether pollution generated in their state contributes to poor air quality in another. If a significant contribution is found, the state must include measures to alleviate this contribution in its State Implementation Plan. EPA must approve these plans. Some downwind states are challenging EPA approvals of State Implementation Plans to control air pollution for Kentucky and Tennessee because they lack a good neighbor provision as required under the Clean Air Act.