What is the Ozone Transport Region and Why Are States Suing the EPA to Enforce It?

Although the issue of pollution carriage was first addressed by the EPA in 1990, there appears to be a growing concern among state regulatory authorities that the current measures taken by the EPA are not stringent enough.  This article will provide an overview of existing regulations and current complaints against the EPA in an effort to inform readers of this re-emerging air quality regulation issue.

What is the Ozone Transport Region?

In 1990, Congress established the Ozone Transport Region (OTR) in the federal Clean Air Act (Section 184(a)) in order to address air pollution in downwind states that is caused by activities in upwind states.  The OTR is essentially a single, 13-state ozone nonattainment area.  The original member states of the OTR are: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, parts of Virginia and the District of Columbia.

The Clean Air Act contains what is known as a “good neighbor” provision, which 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 adopt measures to alleviate this contribution and include these measures in its State Implementation Plan. EPA must approve these plans.

How do air emissions travel from their source to the Ozone Transport Region?

Scientific studies have uncovered a rich complexity in the interaction of meteorology and topography with ozone formation and transport. The evolution of severe ozone episodes in the eastern United States often begins with the movement of a large high pressure area from the Midwest to the middle or southern Atlantic states, where it assimilates into and becomes an extension of the Atlantic (Bermuda) high pressure system. During its movement east, the air mass accumulates air pollutants emitted by large coal-fired power plants and other sources located outside the Ozone Transport Region. As the air mass passes over the eastern United States, sources within the Ozone Transport Region contribute to the air pollution burden.

These expansive weather systems favor the formation of ozone by creating a vast area of clear skies and high temperatures. These two prerequisites for abundant ozone formation are further compounded by a circulation pattern favorable for pollution transport over large distances. In the worst cases, the high pressure systems stall over the eastern United States for days, creating ozone episodes of strong intensity and long duration.

One transport mechanism that has fairly recently come to light and can play a key role in moving pollution long distances is the nocturnal low level jet stream. The jet is a regional scale phenomenon of higher wind speeds that often forms during ozone events a few hundred meters above the ground just above the stable nocturnal boundary layer. It can convey air pollution several hundreds of miles overnight from the southwest to the northeast, directly in line with the major population centers of the Northeast Corridor stretching from Washington, D.C. to Boston, Massachusetts. The nocturnal low level jet extends the entire length of the corridor from Virginia to Maine, and has been observed as far south as Georgia. It can thus be a transport mechanism for bringing ozone and other air pollutants into the Ozone Transport Region from outside the region, as well as move locally formed air pollution from one part of the Ozone Transport Region to another. Other transport mechanisms occur over smaller scales. These include land, sea, mountain, and valley breezes that can selectively affect relatively local areas. They play a vital role in drawing ozone-laden air into some areas, such as coastal Maine, that are far removed from major emission source regions.

What measures have been enacted to enforce the OTR?

During the 1990s, air quality planners began developing and implementing coordinated regional and local control strategies for NOx and VOC emissions that went beyond the previous emphasis on urban-only measures. These measures have resulted in significant improvements in air quality across the Ozone Transport Region. Measured NOx emissions and ambient concentrations have dropped between 1997 and 2005, and the frequency and magnitude of ozone exceedances have declined within the Ozone Transport Region.

In 2014, the State Collaborative on Ozone Transport (SCOOT) was formed from 26 eastern and Midwestern states.  SCOOT’s effort has focused on ensuring that large coal-fired power plants that have purchased pollution controls run those controls when ozone is a problem. Under current laws, many power plants in upwind states can operate without the controls running and nonetheless comply with their long-term pollution limits.

In 2015, environmental officials from SCOOT states asked power plants in their states to increase the use of their controls for nitrogen oxides (NOx), which help to form ozone. This voluntary approach did not work.

Efforts to minimize the upwind pollution transport issue are ongoing.

Emerging State Complaints Regarding Upwind Pollution

On October 27, 2017, EPA denied a petition from Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island and Vermont under section 176A(a) of the Clean Air Act (CAA). The petition asks the EPA to add Illinois, Indiana, Kentucky, Michigan, North Carolina, Ohio, Tennessee, West Virginia and a portion of Virginia to the Ozone Transport Region (OTR), alleging that these states significantly contribute to violations of the 2008 ozone national ambient air quality standards (NAAQS) in the OTR.

On December 26, 2017, eight northeastern states filed against the EPA to cause them to tighten regulations on Midwestern states whose air emissions are blamed for increased smog pollution thanks to prevailing air currents.  In their suit filed on December 26, the coalition of “downwind” states urged the U.S. Court of Appeals for the District of Columbia Circuit to review Pruitt’s denial of the petition, arguing that it is unlawful to vacate it.

On January 9, 2018, Delaware publicly stated its intent to sue the EPA for failing to curb the upwind air pollution generated by power plants in neighboring Pennsylvania and West Virginia.




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