Air pollution can be caused by natural sources, such as volcanic eruptions and forest fires, as well as human activities, such as burning fossil fuels and industrial emissions.

Lead is not a criteria air pollutant, as it is not regulated by the Clean Air Act.

Aerosol scattering is the term for the scattering and absorption of light by particles in the atmosphere, such as dust, smoke, and water droplets.

Acid rain is not a type of visibility impairment, as it does not affect the ability to see through the air.

Haze can be caused by natural sources, such as dust and smoke from forest fires, as well as human activities, such as burning fossil fuels and industrial emissions.

Increasing the use of coal-fired power plants is not a strategy for improving air quality, as coal-fired power plants emit a significant amount of air pollution.

Air pollution control is the term for the process of removing pollutants from the air, such as through the use of filters and scrubbers.

State Implementation Plans are not air quality standards, but rather plans developed by states to achieve the National Ambient Air Quality Standards.

Visibility assessment is the term for the process of assessing the impact of air pollution on visibility, such as through the use of computer models and field measurements.

Solar panels are not air pollution control devices, as they do not remove pollutants from the air.

Emission reduction is the term for the process of reducing the amount of pollutants emitted into the air, such as through the use of cleaner fuels and more efficient technologies.

Acid rain is not a type of visibility impairment, as it does not affect the ability to see through the air.

Smog can be caused by natural sources, such as dust and smoke from forest fires, as well as human activities, such as burning fossil fuels and industrial emissions.

Increasing the use of coal-fired power plants is not a strategy for improving visibility, as coal-fired power plants emit a significant amount of air pollution that can impair visibility.

Air pollution control is the term for the process of removing pollutants from the air, such as through the use of filters and scrubbers.