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Levels of Pollutants

Residents of rural areas typically do not have to worry about the quality of air in the area, but for those living near cities or regions with poor environmental practices, air pollution can be a large detriment to local standard of health. The United States Environmental Protection Agency (EPA) and local air quality agencies monitor air pollution around the country to provide safety instructions and environmental information to citizens and researchers.

  1. Air Quality Index

    • The EPA uses the Air Quality Index (AQI) as a tool to report daily air quality. The AQI serves as an index that provides levels with increasing levels of health concern and colors that coordinate to these levels of air quality. The Clean Air Act regulates the major air pollutants rated by the AQI. These air pollutants are "ground-level ozone, particle pollution, carbon monoxide, and sulfur dioxide," according to the EPA website. As of March 2011, the EPA is reviewing the air quality standard for nitrogen dioxide. The inclusion of this pollutant would change certain elements of the AQI.

    Levels

    • The Air Quality Index is divided into six levels. AQI levels range from zero to 500. When the AQI is in the range of zero to 50, air quality conditions are good. Levels 51 to 100 means the conditions are moderate, while 101 to 150 signals air quality that is unhealthy for sensitive groups. Unhealthy levels range from 151 to 200, while 201 to 300 is very unhealthy and 301 to 500 is hazardous. The colors that symbolize these levels are green, yellow, orange, red, purple and maroon, respectively.

    Health Concerns

    • An AQI rating of good means that the air quality is not harmful and proses minimal health risk. Moderate air quality could give health concern to a small group of people, while the third AQI level could harmfully affect people with heart or lung disease, children and older adults. If the air quality is unhealthy, most people will experience poor health effects, and very unhealthy air pollution can "trigger a health alert, meaning everyone may experience more serious health effects," according to EPA's website. When the AQI is at a hazardous level, the EPA warns that the entire population will experience bad health effects.

    Measuring AQI

    • The EPA uses the AQI to test concentrations of major pollutants at over 1,000 locations around the nation. The EPA then converts these measurements into a separate value for each pollutant. Whichever pollutant provides the highest AQI value is announced as the level for that day in a particular region. If a city has more than 350,000 people, local agencies must report the AQI to the public every day. If the AQI is above 100, these agencies must report which specific groups of people are more prone to ill health effects.

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