By Neil Carman
With the 2016 ozone season half over, the Houston and Dallas-Fort Worth (DFW) areas have by far the most high ozone days in the state compared to urban areas with just a few exceedance days: San Antonio, El Paso, Beaumont-Port Arthur, and East Texas. The statewide total is 86 exceedances during 27 days. The 2016 ozone season is using a new EPA standard of 70 ppb for eight hours, and frankly, I expected more exceedances than we have seen in all the large urban areas. However, each year, vehicles are cleaner and ozone levels reflect the fact that most people are driving less polluting cars and trucks. Smoking vehicles are becoming a rare sight whereas it used to be common.
For a quick refresher on what ozone is and why it’s dangerous, check out our ozone issue page.
Houston has observed 15 days and 46 exceedances with peak 8-hour levels at 89 parts per billion (ppb). The Houston area’s exceedances are significant since nine monitors have violated the three-year average (2014-16) of 70 ppb compared to 13 monitors violating it in 2013-15. This evidence supports why the Houston area will be in nonattainment for the new EPA ozone standard, and Houston is still not meeting the 2008 standard of 75 ppb. Houston’s peak ozone events continue to be centered in highly industrialized Harris County where the air pollution problems have been the worst in the eight-county region for decades.
DFW has reported nine high ozone days and 28 exceedances but has measured the highest levels in Texas at 95 ppb. The DFW area’s exceedances are significant since 10 monitors have violated the three-year average (2014-16) of 70 ppb compared to 12 monitors violating it in 2013-15. The DFW area receives a significant ozone pollution impact from coal plants in East Texas and Central Texas, and it appears that a lower transport effect has occurred this year. The ozone evidence supports why the DFW area will be in nonattainment for the new EPA ozone standard, and that DFW is still not meeting the 2008 standard of 75 ppb.
August tends to be the worst ozone month for reasons that are unknown, and in recent years, both Houston and DFW areas have had high numbers of bad air days in August and ozone at some of the highest 8-hour peaks each year.
Neil Carman is the Clean Air Program Director of the Sierra Club's Lone Star Chapter.