By Neil Carman
Ground level ozone continues to be the worst air pollution challenge facing Texas. The good news is that cities are making progress to clean up ozone air pollution in all areas in Texas, finally complying with the older 1-hour standard adopted in 1979 and the outdated 8-hour standard set in 1997. Now for the bad news.
Texas cities have some of the highest ozone (better known as smog) levels in the nation - not far behind the Los Angeles basin, - and 2016 is proving to be no different. Houston, San Antonio, and Port Arthur have already seen ozone this spring that exceeds the EPA’s standard. (Check out our resource page for ozone basics)
Every year, the Dallas-Fort Worth area and Houston area have the worst ozone levels in Texas with millions of people being exposed to this harmful air pollutant. Based on three years of ozone monitoring data in 2013-14-15, Dallas-Fort Worth and Houston are expected to be designated in violation of ozone “nonattainment” in 2017 when the EPA declares which American cities fail to meet the new standard.
When the EPA adopted the new 8-hour ozone standard last Fall (70 parts per billion (ppb)), it set the stage for exceedances below the old standard (75 ppb) that uses a three-year average based on a monitor’s fourth-highest daily maximum each year. Utilizing three years of ozone data (2013-15), how are these areas fairing?
Dallas-Fort Worth
Dallas-Fort Worth had 12 monitors violating the new standard with the highest violation measured in Denton County — 83 ppb — revealing a long ways to go to meet 70 ppb.
The air monitors show that the sprawling DFW area’s worst ozone is centered in Denton, Dallas, Tarrant and Collin counties, where most of the Metroplex’s six million people live and work with large volumes of commuter traffic. In addition, a cluster of dirty East Texas coal plants, Midlothian cement kilns, and thousands of natural gas wells are big contributors to the DFW metroplex ozone pollution, supplying large volumes of volatile organic chemicals and nitrogen oxides that form ozone in sunlight. DFW is now a 10-county nonattainment area and TCEQ proposes to add Hood County based on 2013-15 data.
Houston
The Houston area (eight counties) faces a similar geographic challenge but with a different mix of smog-forming sources. According to 2013-15 ozone data, Houston had 13 monitors indicating violations of the new standard with the peak measurements at Manvel Croix Park in Brazoria County to the southwest of the city — with an80 ppb average — while 10 other monitors in violation are in Harris County (Houston), one at Galveston, and another at Conroe.
A big reason for the Houston area’s ozone pollution is its being home to the largest concentration of industrial plants in the nation along the 23-mile Houston Ship Channel just east of the city. The Ship Channel has several hundred major chemical plants and petroleum refineries releasing lots of smog-forming chemicals.
Why Should Texas Communities Care?
In 2016, Texas urban areas are seeing rising ozone levels across the state, making breathing outside more risky, especially in the afternoons when ozone reaches its highest hourly peaks. Healthwise, ozone is an outdoor risk since it can harm lung tissue and even kill cells if its spikes too high. Children, sensitive breathers with lung disease, the elderly, and outdoor workers are the most in danger.
Once again, cities in Texas had among the highest ozone readings in the nation in April and May as Spring weather brought sunny warm days ripe for ozone formation. Urban air pollution dominated by ground level ozone is an ongoing challenge due to a mix of growing populations, more vehicles (albeit cleaner), and industrial pollution that come together with sunlight to create smog.
What Does the New Ozone Standard Reveal?
As of May 24, 56% of Texas ozone exceedances this year ranged from 71-75 ppb above the new standard, and the other 44% were in the 76-89 ppb range (above the old 75 ppb standard). Exceedances of the new standard mean that Texas cities that are in violation will have to finds ways to reduce smog-forming chemicals in the air from vehicles and industry. Higher ozone levels indicate the ambient air is dirtier to breathe, and clearly that means the 44% of exceedances in the 76-89 ppb range are worse than the 71-75 ppb exceedances.
During this Spring, Houston, San Antonio, and Port Arthur had multiple days with high ozone, while Dallas-Fort Worth had none as of May 24. Cities with ozone close to exceeding the standard include Austin, Waco, Temple, El Paso, Tyler, and Beaumont.
Despite the DFW area failing to observe any bad air days so far this Spring, the 8-hour ozone readings have been high enough that the 3-year average at four DFW monitoring sites exceed the new 70 ppb standard.
Meanwhile the Houston area has seen the highest 8-hour levels over twelve days spread among 16 monitors. Houston is leading the state with 35 ozone exceedances.
San Antonio also has two monitors that now reveal they exceed the new EPA standard with 3-year, 8-hour averages at 71 ppb, adding to the weight of evidence in 2013-15 that the same two sites are in violation. San Antonio’s Alamo Area Council of Governments has written to the TCEQ asking that the region not be proposed for nonattainment designation when the TCEQ sends its recommended designations to the EPA in September.
When EPA set a new 8-hour ozone standard of 70 ppb on October 1, 2015, the news meant that San Antonio and El Paso will likely join the DFW and Houston areas as having excessive ozone over 8-hour periods. Texas will go from the current 18 counties in nonattainment to at least 21 counties. But the total may be as high as 28 counties if the EPA designates the entire San Antonio-New Braunfels MSA (8-counties) in ozone nonattainment.
Stay tuned to this blog and our Facebook page for more updates on ozone violations, and be sure to sign up to receive bad air alerts on your phone.
Neil Carman is Clean Air Director at the Sierra Club’s Lone Star Chapter.