To protect human health

To protect the environment

To promote economic growth

To improve air quality

Particulate matter

Ozone

Carbon dioxide

Sulfur dioxide

A federal law in the United States that regulates air emissions from stationary and mobile sources

A state law in California that regulates air emissions from vehicles

An international treaty that sets limits on air pollution

A non-profit organization that advocates for clean air

A set of limits on air pollution levels set by the U.S. Environmental Protection Agency (EPA)

A set of limits on air pollution levels set by the World Health Organization (WHO)

A set of limits on air pollution levels set by the European Union (EU)

A set of limits on air pollution levels set by the United Nations (UN)

To protect human health

To protect the environment

To promote economic growth

To improve air quality

Particulate matter, ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead

Particulate matter, ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and mercury

Particulate matter, ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and arsenic

Particulate matter, ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and benzene

Primary air pollutants are emitted directly from sources, while secondary air pollutants are formed in the atmosphere from chemical reactions between primary air pollutants

Primary air pollutants are emitted from natural sources, while secondary air pollutants are emitted from human-made sources

Primary air pollutants are harmful to human health, while secondary air pollutants are not

Primary air pollutants are regulated by the NAAQS, while secondary air pollutants are not

Fossil fuel combustion, industrial processes, and construction activities

Motor vehicles, power plants, and wildfires

Agriculture, forestry, and mining activities

All of the above

Motor vehicles, power plants, and industrial facilities

Sunlight, heat, and volatile organic compounds (VOCs)

Natural sources, such as trees and plants

All of the above

Motor vehicles, power plants, and industrial facilities

Sunlight, heat, and volatile organic compounds (VOCs)

Natural sources, such as trees and plants

All of the above

Fossil fuel combustion, industrial processes, and smelting activities

Motor vehicles, power plants, and wildfires

Agriculture, forestry, and mining activities

All of the above

Motor vehicles, power plants, and industrial facilities

Sunlight, heat, and volatile organic compounds (VOCs)

Natural sources, such as trees and plants

All of the above

Motor vehicles, smelters, and battery manufacturing facilities

Power plants, industrial facilities, and mining activities

Agriculture, forestry, and construction activities

All of the above

Respiratory problems, such as asthma and bronchitis

Cardiovascular problems, such as heart attacks and strokes

Cancer

All of the above

Respiratory problems, such as asthma and bronchitis

Cardiovascular problems, such as heart attacks and strokes

Cancer

All of the above

Headaches, dizziness, and fatigue

Nausea, vomiting, and diarrhea

Heart problems, such as chest pain and shortness of breath

All of the above

Respiratory problems, such as asthma and bronchitis

Cardiovascular problems, such as heart attacks and strokes

Cancer

All of the above

Respiratory problems, such as asthma and bronchitis

Cardiovascular problems, such as heart attacks and strokes

Cancer

All of the above

Brain damage, especially in children

Kidney damage

Reproductive problems

All of the above