Despite "significantly" improved air quality, as determined by the U.S. Environmental Protection Agency (EPA), Dallas-Fort Worth (DFW) is facing reclassification as being in "severe nonattainment" of an eight-hour ozone standard of 84 parts per billion (ppb).
EPA is taking public comment on the proposed reclassification during a 30-day period to begin once its notice is published in the Federal Register, the agency said Tuesday.
EPA has been working with Texas Commission on Environmental Quality (TCEQ), North Central Texas Council of Governments, elected officials and statewide environmental organizations in preparation for the proposed action. While DFW's air quality has steadily improved as its population grows, the area missed a June 2013 deadline to attain the 1997 ozone standard, EPA said. Because the area did not meet the deadline of June 15, 2013, to attain the 1997 standard, the Clean Air Act requires EPA to reclassify DFW as a severe nonattainment area.
The agency revised the eight-hour health-based standard for ozone in 2008. In 2013, EPA proposed for public comment guidelines for the revised standard, including plans to revoke the 1997 ozone standard for all purposes and to no longer reclassify areas under the old standard. However, the proposal still is not final.
TCEQ developed a plan for the revised 2008 ozone standard and is expected to submit it to EPA for review by July.
DFW air quality has significantly improved over the last decade. Ten years ago, the eight-hour average was 98 ppb; the preliminary value for 2010-2014 is 81 ppb. During that time, DFW has also been among the fastest-growing regions in the country.
While some critics have pointed to natural gas development in the Barnett Shale, over much of which DFW lies, the natural gas industry disputes the assertion. However, according to TCEQ data, vehicular emissions far exceed those from Barnett Shale natural gas development activities.
According to EPA, the area's improved air quality came through a combination of federal measures to clean up fuels and reduce emissions from engines, state measures to reduce emissions from stationary sources, and efforts of the public during ozone season -- including using public transport, refueling in the evenings, and properly maintaining their vehicles.