About Air Pollution

All human activities add gases and particles to the air we breathe. When these gases and particles, or air pollutants, accumulate in the air in high enough concentrations, they can harm us and our environment.

In response to the identification of air pollution as a national problem that needed a comprehensive program to address it, Congress passed the Clean Air Act and the U.S. Environmental Protection Agency was established to implement it and other environmental laws.

As part of the Clean Air Act, all communities in the U.S. must meet the National Ambient Air Quality Standards (NAAQS) for six major (aka "criteria") air pollutants. Here is the current NAAQS status in Louisville for those air pollutants.

Human-generated (also called "anthropogenic") sources of air pollution can be broken down into two categories: Mobile and stationary.

Mobile sources of air pollution include most forms of transportation such as on-road vehicles like automobiles and trucks, as well as non-road equipment like tractors, backhoes, trains, and airplanes.

Stationary sources of air pollution consist of non-moving sources, such as power plants, industrial facilities, gas stations, and paint booths. Stationary sources are further divided into two classifications: point sources and area sources.

Point sources are large stationary sources of emissions that have specific locations and release pollutants in quantities above a certain emission threshold. Point sources include large factories and electric power plants.

Area sources represent numerous facilities or activities that individually release small amounts of a given pollutant, but collectively can result in significant amounts of emissions. For example, dry cleaners, vehicle refinishing, gasoline-dispensing facilities, and residential heating will not typically qualify as point sources, but collectively the various emissions from these sources are classified as area sources.

The Air Pollution Control District monitors our local air and reports the daily air quality using the Air Quality Index as a guide.

Visit our Glossary of Air Pollution Terms and Abbreviations for an extensive collection of words, phrases, acronyms and abbreviations used in air pollution control and air pollution monitoring.