Protecting Public Health and the Environment.

Air Pollutants

An air pollutant is any substance in the air that can cause harm to humans or the environment. Pollutants may be natural or human-made and may take the form of solid particles, liquid droplets, or gases. Natural sources of air pollution include smoke from wildfires, dust, and even volcanic ash. Human-made sources of air pollution include emissions from vehicles and factories; dust from unpaved roads, agriculture, or construction sites; and smoke from human-caused fires.

In Idaho, pollutants of concern include particulate emissions from vehicles and industrial sources that get trapped by wintertime inversions, chemicals and particulates from smoke from fires, and ground-level ozone that forms during hot summer days.

Breathing elevated levels of air pollutants can adversely affect human health, especially among sensitive populations such as children, the elderly, and those with heart or lung diseases. Potential health problems include lung damage, birth defects, nerve damage, reduced immunity, and an increased risk of developing cancer.

The following information provides an overview of various types of air pollutants and their health impacts.

Air Toxics

Air toxics is a term that refers to the 188 hazardous air pollutants (HAPs) listed in the Clean Air Act (CAA) of 1990 that are known or suspected of causing cancer or other serious health effects. The pollutants listed as HAPs include industrial chemicals, solvents, metals, pesticides, and combustion by-products. Learn more.

Criteria Pollutants

EPA has set health-based National Ambient Air Quality Standards (NAAQS) for six pollutants: carbon monoxide, lead, ozone, nitrogen dioxide, particulate matter, and sulfur dioxide. Learn more.


Fugitive Dust

Fugitive dust is particulate matter, or particle pollution, that becomes airborne from activities such as construction, commercial mining, driving on unpaved roads, demolition, and soil and wind erosion. Under certain conditions and in certain quantities, fugitive dust can be harmful to human health and a public nuisance. Learn more.

Greenhouse Gases

Gases that absorb and trap heat in the atmosphere are often called greenhouse gases. Many of these gases are naturally occurring and are essential to life on earth by providing a blanket for marine and terrestrial organisms. Without them, temperatures on earth would be intolerably cold. However, when their concentrations become too high, they may contribute to global warming. Learn more.


    One of the most common forms of air pollution—haze—degrades visibility in many American cities and scenic areas. Haze is caused when sunlight encounters tiny pollution particles in the air, which reduce the clarity and color of what we see. Learn more.


    Odors are a concern for Idahoans and a frequent source of citizen complaints. Odors are generated by a wide range of operations, including livestock feedlots, wastewater treatment plants, and various other industries. Learn more.

    Vehicle Emissions

    Vehicles emit many pollutants into the air. While emissions from an individual vehicle may be minimal, emissions from many vehicles on the road at one time can have a serious impact on air quality. Learn more.

    Visible Emissions

    A wide range of industries produce visible emissions. They are introduced into the atmosphere by sources such as stacks, vents, and conveyor lines. Learn more.