The US Environmental Protection Agency has approved Texas’s state implementation plan (SIP) to limit emissions of substances leading to the formation of ground-level ozone. EPA’s Sept. 23 approval effectively said the plan will let the state meet 2015 National Ambient Air Quality Standards (NAAQS) and comply with the 1970 Clean Air Act.
“Texas understands how to run an effective air quality program,” EPA Regional Administrator Ken McQueen, who is based in Dallas, said. “This plan shows the state’s continued commitment to protecting communities throughout the state by meeting federal air quality requirements.”
McQueen said this type of SIP is commonly referred to as an infrastructure SIP because it addresses the basic requirements of state air-quality management programs, such as air-quality monitoring and enforcement. States are required to submit a SIP within 3 years after a new or revised NAAQS to ensure the state meets its responsibilities under the Clean Air Act.
EPA approved Texas’ infrastructure SIP except for certain portions relating to interstate transport of air pollutants. The remaining parts of the plan will be addressed in future, separate actions, McQueen said.
Ground-level ozone is not emitted directly into the air but is formed when nitrogen oxides (NOx) and volatile organic compounds (VOC) react in the presence of sunlight. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOCs, EPA noted.
It said that nationally, the concentration of ground-level ozone decreased 17% from 2000 to 2017. Levels of all other air pollutants regulated under NAAQS—carbon monoxide, lead, nitrogen dioxide, particulate matter and sulfur dioxide—also have fallen substantially thanks to the various quality management and control strategies developed and implemented at the local, state, regional, and national level, EPA said.
