Emissions is the term used to describe the gases and particles put into the air by a variety of sources, including factories, power plants, motor vehicles, airplanes and natural sources such as trees and vegetation. These emissions can pose health risks and contribute to air pollution, global warming and the destruction of the ozone layer. Under the auspices of the Clean Air Act and its amendments, the EPA measures, evaluates and reports emissions data with the goal of improving air quality. The EPA also plays an important role in researching new methods of assessing the impact of air pollution emissions on the environment and developing new ways to curb these emissions.

Recommended EPA Web pages

• Emissions Measurement Center
  This is the homepage for the Emissions Measurement Center.
• Air Pollution Emissions Overview
  Provides an overview of the sources and measurement of air pollution emmissions.
• National Emissions Inventory (NEI) Air Pollutant Emissions Trends Data
  Provides information about National Emissions Inventory air pollutant emissions trends data.

Air Pollution
Certification Programs, Community Involvement, Industrial Air Pollution, New Source Review, Research, State Implementation Plans, Stationary Sources, Testing, Transboundary Pollution, Urban Air Pollution

Air Pollution Control
Abatement, Remediation, Treatment

Air Pollution Effects
Acid Rain, Climate Change, Economic Effects, Environmental Effects, Global Warming, Health Effects, Heat Island Effect, Risk Assessment

Air Pollution Legal Aspects
Compliance, Enforcement, Guidance, Legislation, Permits, Public Comment, Regulations, Reporting, Standards

Air Quality
Air Quality Criteria, Attainment, Early Action Compacts, Emission Factor, Emission Inventory, Emissions, Emissions Measurement, Emissions Trading, Measurement, Models, Monitoring, Nonattainment

Atmosphere
Carbon Sequestration, Climate Change, Global Warming, Ground Level Ozone, Ozone Depletion, Ozone Layer, Ozone Monitoring, Ozone Transport, Smog, Ultraviolet Radiation (UV)

Indoor Air Pollution
Building Related Illness, Carbon Monoxide, Environmental Tobacco Smoke, Fireplaces, Mercury, Mold, Radon, Sick Building Syndrome, Stoves, Vermiculite, World Trade Center Dust Cleanup

Mobile Sources
Airplanes, Automobiles, Diesels, Engines, Fuels, Inspection and Maintenance, Lawn and Garden Equipment, Locomotives, Marine Engines, Motorcycles, Trucks and Buses, Used Oil Recycling, Vehicle Emissions