Air pollution

Atmosphere

The layer of gases that surround the planet, relatively thin compared to the size of Earth.

Primary Pollutants

Polluting compounds that come directly from sources such as smoke-stacks or exhaust pipes.

Secondary Pollutants

Pollutants that form in the atmosphere from chemical reactions of primary pollutants, sunlight, and water.

Ozone Layer

A region within the stratosphere with higher concentrations of ozone that absorbs UV radiation from the sun.

Air Pollution

Material added to the atmosphere that can affect climate and harm organisms, including humans.

Industrial Smog

Smog produced by industrial pollution, mainly from burning sulfur-rich fossil fuels.

Photochemical Smog

Smog formed from the reaction of sunlight with pollutants, such as nitrogen oxides and volatile organic compounds.

Acid Deposition

The deposition of acidic pollutants from the atmosphere, resulting in acid rain, fog, or snow.

Urban Heat Island Effect

A phenomenon where urban areas become hotter than their rural surroundings due to human activities.

Clean Air Act

A U.S. law established to regulate and set standards for air quality and reduce air pollution.

Criteria Air Pollutants

Six pollutants for which the EPA is required to set acceptable levels due to their impact on public health and the environment: SO2, NOx, CO, Pb, PM, and ozone.

Carbon Monoxide (CO)

A colorless, odorless gas resulting from incomplete burning of fossil fuels, hazardous to human health.

Lead (Pb)

A neurotoxicant released from metal smelting and burning waste, hazardous to health.

Sulfur Dioxide (SO2)

A colorless gas produced from burning sulfur-containing fossil fuels; a respiratory irritant and precursor to acid rain.

Nitrogen Oxides (NOx)

Pollutants formed from burning fossil fuels, contributing to smog and respiratory issues.

Particulate Matter (PM)

Tiny particles suspended in air, generated from fuel combustion that can harm human health.