Which of the following is NOT a criteria pollutant according to the Clean Air Act?

Chlorofluorocarbons (CFCs) are not considered criteria pollutants under the Clean Air Act. Criteria pollutants are specific air pollutants regulated by the United States Environmental Protection Agency (EPA) because of their widespread nature and potential to harm human health and the environment.

The Clean Air Act identifies six criteria pollutants, which include lead, carbon monoxide, ozone, nitrogen dioxide, sulfur dioxide, and particulate matter. These pollutants are monitored and assessed based on health and environmental standards. CFCs, on the other hand, were primarily targeted for regulation due to their role in ozone depletion in the stratosphere, rather than direct health impacts in the troposphere.

Consequently, while CFCs are regulated under different provisions related to stratospheric ozone protection, they do not fit into the category of criteria pollutants that are subject to the same monitoring and standards as the other listed options. This distinction highlights the specific focus of criteria pollutants in relation to immediate air quality and public health concerns, separate from those substances related to longer-term environmental impacts.