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Alamo area struggles to remain in compliance with ozone standard

Special to the Courier

July 15 marked the midway point in the Ozone Season - that time of year stretching from April through September when the area's most prevalent form of air pollution, ozone, tends to spike. At the midway milestone, the San Antonio-New Braunfels Metropolitan Statistical Area (MSA) is in compliance with federal standards. The prevalence of cloudy skies and cooler temperatures this spring helped keep our ozone levels low. However, remaining in compliance is a tenuous situation, first because the season is only half over, and second because the ozone standards are about to change.
"According to the current standards of the Environmental Protection Agency set in 2008," explains Brenda Williams, Interim Director of Natural Resources at the Alamo Area Council of Governments (AACOG), "our status is based on a three year average of the fourth highest eight-hour daily ozone reading per year at the areas three regulatory monitors. To remain within the federal standards, that three year average at each monitor must be lower than 76 parts per billion."
As of July 15, the fourth highest daily maximum eight-hour ozone concentrations measured at the area's three regulatory monitoring sites during the 2015 Ozone Season were 66 ppb at the San Antonio Northwest monitor, 67 ppb at the Camp Bullis monitor, and 60 ppb at the Calaveras Lake monitor. When those fourth highest readings are averaged with the fourth highest readings from 2013 and 2014, the three year averages were 70 ppb at San Antonio Northwest, 74 ppb at Camp Bullis, and 64 at Calaveras Lake. (Source: http://www.tceq.state.tx.us/cgi-bin/compliance/monops/8hr_attainment.pl)
If the current ozone season were now over, the three-year average at none of the regulatory monitors would be exceeding the standard of 75 ppb for ground level ozone. That's good news, because unlike the ozone in the Earth's upper atmosphere that protects us from the sun's ultraviolet rays, ozone at ground level is a health hazard that can cause respiratory irritation and pain, trigger or even cause asthma, and reduce lung capacity and function. As Williams points out, however, "several months still remain in the ozone season, with the worst peaks in ozone typically occurring in September. It will be a challenge to remain in compliance with the current standards through the end of the season."
In addition, the EPA has stated that it will lower the acceptable threshold for ozone to somewhere between 65 and 70 ppb later in this year, in the interests of better protecting public health and the environment. It is expected that next year's attainment status for the MSA (which would be an average of the fourth highest eight hour average readings of 2014, 2015, and 2016), will be based on that new standard.
Failure to meet air quality standards will likely result in steps that local governments would be required to implement in order to reduce pollution and regain our clean air status. For example, new or expanding manufacturers may be required to secure pollution reductions to offset their proposed growth, and transportation planners may be required to prove that adding capacity to the roadway system would not increase pollution from cars and trucks to qualify for federal highway funds for roadway improvements.
Ground-level ozone forms in intense sunlight when nitrogen oxides (such as those found in gasoline exhaust and other emissions from fossil fuel combustion), combine with volatile organic compounds (such as those found in gasoline vapors and solvent fumes). It builds up in the air we breathe when winds are light or the air is still.
The City of San Antonio, the Alamo Area Metropolitan Planning Organization, and other area governmental entities represented on AACOG's Air Improvement Resources (AIR) Committee are developing strategies for improving air quality. "Keeping our levels of air pollution down is a challenge that requires a shared commitment from regional agencies and businesses, as well as individuals," said Williams.