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.

Louisville Metro, like all communities in the U.S., must meet the National Ambient Air Quality Standards (NAAQS) for six major air pollutants as set forth in the Clean Air Act. 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 sources of air pollution include most forms of transportation such as onroad vehicles like automobiles and trucks, as well as nonroad equipment including 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.

Large stationary sources of emissions that have specific locations and release pollutants in quantities above a certain emission threshold are known as point sources. Those facilities or activities whose individual emissions do not qualify them as point sources are called area sources.

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. Click here for more forecast information as well as on the AQI and on how you can be better informed about local air quality.

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