Under the Clean Air Act, EPA establishes air quality standards to protect public health and the environment. EPA has set national air quality standards for six common air pollutants. These include:
- carbon monoxide,
- nitrogen dioxide,
- particulate matter (also known as particle pollution), and
- sulfur dioxide.
Each year EPA tracks the levels of these pollutants in the air and how much of each pollutant (or the pollutants that form them) is emitted from various pollution sources. The Agency looks at these numbers year after year to see how the pollutants have changed over time. EPA posts the results of our analyses to this web site.
Air Quality and Emissions Progress Continues in 2011
National average air quality continues to improve as emissions decline through 2011.
Basic Information - Information about air quality standards for the six common air pollutants, also called criteria pollutants.
Air Quality Trends by Pollutant:
- Carbon Monoxide (CO)
- Ground-level Ozone (O3)
- Lead (Pb)
- Nitrogen Dioxide (NO2)
- Particulate Matter (PM)
- Sulfur Dioxide (SO2)
Where You Live - View local-area air trends for the six common air pollutants.
Reports and Data - View and download current and past Air Trends Reports, EPA's "report card" on the status of air quality and air pollutant emissions.
Special Studies - Links to special study topics regarding policy-relevant information related to air quality trends.
Air Quality Data and Regulatory Statistics:
- Design Values - Statistics that describe the air quality status of a given area relative to the level of EPA's National Ambient Air Quality Standards.
- Air Quality Monitoring Information - Trends data and statistics for cities and counties.
- Air Quality Index (AQI) Information - Numbers of days with AQI values greater than 100 and trends for cities.
Acronyms - A list of common acronyms used throughout the Air Trends site.