On October 1, 2015, the EPA revised the primary NAAQS for ozone from an eight-hour standard at 0.075 ppm to an eight-hour standard at 0.070 ppm. The EPA also revised the secondary NAAQS for ozone, intended to protect public welfare, to 0.070 ppm (equivalent to the primary standard).
Based on preliminary air monitoring data for 2015, four areas in Texas would not meet the new ozone standard: Dallas-Fort Worth, Houston-Galveston-Brazoria, San Antonio, and El Paso. Recommendations from states on the attainment status of each county within the state with regard to the new standard are scheduled to be due to the EPA by October 1, 2016. States’ recommendations will likely be based on the latest complete monitoring data available at that time (2013-2015). Nonattainment designations for the 2015 ozone NAAQS are scheduled to be final by October 1, 2017 and will be based on the latest air monitoring data (2014-2016) available at that time.