WASHINGTON (DC News Now) — The Air Quality Index is used for reporting on the daily air conditions, how clean or polluted the air is, and how it will affect you and your outdoor activities.

The Environmental Protection Agency established the index, which is based on the measurement of five major air pollutants, under the Clean Air Act. Those pollutants are: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide. The index is broken into six categories or codes: green, yellow, orange, red, purple, and maroon.

The colors represent a numbered scale, with green being good and maroon meaning hazardous.

An Air Quality Index of zero to 50, or Code Green, means the air is good and there is little to no risk. Between 50 to 100 is Code Yellow, which means the air quality is moderate; however, it may pose a risk for those who are unusually sensitive to air pollution.

Code Orange is between 101 to 150 and while the general public is not likely to be affected, it may cause health effects to sensitive groups. When the Air Quality Index is between 151 to 200, it is Code Red, meaning it is unhealthy.

The general public may experience health effects and it could be serious for members of sensitive groups.

Code Purple ranges from 201 to 300 on the index scale and is considered to be very unhealthy, as the risk of health effects is increased for everyone.

The most hazardous is Code Maroon which ranges from 301 to 500 and everyone is likely to be affected.

To check the air quality where you live, visit AirNow.