0.070 parts per million

The Clean Air Act regulates ozone as a criteria pollutant. The U.S. EPA sets National Ambient Air Quality Standards (NAAQS) for ozone, including both primary standards to protect public health and secondary standards to protect the environment.

Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth’s upper atmosphere. (the stratosphere) and lower atmosphere (the troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways.

EPA has established national ambient air quality standards (NAAQS) for six of the most common air pollutants— carbon monoxide, lead, ground-level ozone, particulate matter, nitrogen dioxide, and sulfur dioxide—known as “criteria” air pollutants (or simply “criteria pollutants”).

The Environmental Protection Agency (EPA) said it was withdrawing the “once-in always-in” policy under the Clean Air Act, which dictated how major sources of hazardous air pollutants are regulated.

In June 2019, EPA issued the final Affordable Clean Energy rule (ACE) and repealed the Clean Power Plan.

EPA that carbon dioxide and other greenhouse gases are pollutants that can be regulated under the Clean Air Act.

For more than forty-five years the Clean Air Act has cut pollution as the U.S. economy has grown. Clean Air Act programs have lowered levels of six common pollutants — particles, ozone, lead, carbon monoxide, nitrogen dioxide and sulfur dioxide — as well as numerous toxic pollutants.

The Clean Air Act has helped: cut ground-level ozone, a dangerous component of smog, by more than 25 percent since 1980; reduce mercury emissions by 45 percent since 1990; reduce the lead content in gasoline, which has cut lead air pollution by 92 percent since 1980.

160,000 lives

Clean Air Act Benefit-Cost Studies Fewer premature deaths and illnesses means Americans experience longer lives, better quality of life, lower medical expenses, fewer school absences, and better worker productivity. Peer-reviewed studies show that the Act has been a good economic investment for America.