The U.S. Environmental Protection Agency (EPA) has proposed moving the Dallas-Ft. Worth, Texas region into the severe category regarding the area’s non-attainment of the 1997 eight-hour, 84-parts-per-billion (ppb) standard of ozone.
“EPA has been coordinating closely with Texas Commission on Environmental Quality (TCEQ), North Central Texas Council of Governments, elected officials and statewide environmental organizations in preparation for today’s [Feb. 10, 2015] proposed action,” the EPA wrote in its “EPA Proposes to Move DFW Area into Severe Ozone Category” news release. “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. 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 first thing I’d be asking is why the DFW region has not met even this old ozone standard. In 2008, the standard was tightened to 75 ppb. The 75 ppb standard, itself even more stringent than the one preceding it, may still not be health protective enough. A decision regarding supplanting the newer standard with something tougher (purported to be between 65 and 70 ppb) is expected to be rendered no later than Oct. this year.
“EPA revised the 8-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, this proposal still is not final,” wrote the EPA in the release.
As for how much air quality in the Dallas-Ft. Worth area has improved, the eight-hour average in 2005 was 98 ppb. Meanwhile, for the 2010 through 2014 period, the average is 81 ppb, but that’s a preliminary value, according to the EPA. “During that time, DFW has also been among the fastest-growing regions in the country.”
So, quick review: DFW air quality is steadily improving though area failed to meet 84-ppb ozone health standard as of June 15, 2013 deadline. Preliminarily, though, as I understand it, the standard is met with the 2010-2014 average being 81 ppb. EPA, apparently, is still required to declare DFW as a severe non-attainment area for ozone as per CAA dictate.
Owing to the improvement are federal, state and citizen efforts aimed at helping clean up area air. Federal efforts came in the form of measures to reduce engine emissions and make fuels cleaner; state emissions-reduction efforts were stationary sources sector-based; while the public did its part “during the ozone season” by keeping vehicles properly maintained, by putting off until evenings vehicle refueling and by “using public transport,” the EPA stressed.
Area traffic can at times be considerable, that with abundant horizontal residential development (sprawl, in other words), and warm temperatures makes the area ripe for ozone formation.
Adds the EPA: “In DFW, mobile sources such as cars and trucks are the biggest emitters of ozone ‘ingredients.’ Breathing ozone can trigger a variety of health problems, particularly for children, the elderly, and people of all ages who have lung diseases such as asthma. Ground-level ozone contributes to the formation of smog, and can harm sensitive vegetation and ecosystems.”
Image above: W. R. Howell, Jr.