Waid Environmental News
In the field of air quality and air pollution, there are two types of ozone: tropospheric ozone, and stratospheric ozone. When you hear reports about ‘the growing hole in the ozone layer’, those studies are in reference to stratospheric ozone. The only main difference between these two ‘types’ of ozone are where they are located. The ozone layer starts at around 6 to 10 miles above the Earth’s surface, and extends up to around 30 miles. The ozone layer provides enormous benefits to all living things at the surface of the earth by blocking UV radiation that would otherwise reach the surface and cause molecular mutations. Tropospheric ozone by contrast is found at the surface of the earth. While it provides benefits to us in the stratosphere, down at the surface ozone acts mainly as a powerful oxidizing agent due to its highly reactive nature. The result of this is a degradation in human and environmental health. Ozone is what is referred to as a secondary pollutant, meaning that it is not emitted directly into the atmosphere, but instead is formed from other pollutants that are emitted.
With the passage of the Clean Air Act and it’s subsequent amendments, a federal mandated limit was placed on tropospheric ozone across the country. Counties around the country whose air exceeds the national standard are considered ‘out of attainment’ or in ‘nonattainment’ for that standard. In 2015, a new (tropospheric) ozone standard was proposed for 8-hour average concentrations of ozone. The previous 8-hour NAAQS level was set in 2008 and set a ground-level limit on ozone of 75 parts per million. The 2015 limit reduces this to 70 ppm. New attainment/nonattainment designations are now required per the Texas State Implementation Plan of the Clean Air Act, which will have a direct effect on future permitting actions within each county
Currently all counties within Texas remain with a ‘Pending’ status for the 2015 Ozone national standard. However, on August 3, 2016, the state commission (Texas Commission on Environmental Quality) took the next step forward by approving designation recommendations for all areas. TCEQ staff recommended that all counties in Texas with regulatory ozone monitors exceeding 70 ppm based on air monitoring data from 2013 to 2015 be designated as nonattainment for the 2015 ozone NAAQS. It was also recommended that all counties currently in nonattainment for the 2008 NAAQS level be designated as nonattainment for the 2015 level. This proposal will result in NEW nonattainment designations for Bexar, Hood, and El Paso Counties. The staff also recommended that the nonattainment designation for these three counties could be revised to attainment if they can meet the 2015 NAAQS level with monitoring data from 2016. The recommended designations will be provided to the governor for his consideration for submittal to the EPA by October 1, 2016
You can read the entire designation recommendation to the Governor on the TCEQ’s website here.