Much of what we typically call smog is primarily made up of ground-level ozone.
Ozone can be good or bad, depending on where it is located.
Ozone in the stratosphere high above the earth protects human health and the environment, but ground-level ozone is the main harmful ingredient in smog. TSDFs were found to be responsible for nearly 8 percent of the nation's VOC emissions. The standards for controlling the emissions from TSDFs and LQGs are more commonly known as the RCRA air emission standards. The RCRA air emission standards were promulgated in phases. The scope of the last phase of the RCRA air emission standards, Phase III, will depend on the ability of Subparts AA, BB, and CC to effectively reduce volatile organic emissions.