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Air Quality Index (AQI) Legend and Additional Information


New York State Air Quality Hotline: (800) 535-1345

More information from this division:


  • Air Quality Index
  • Fine Particles
  • Ozone
  • More Information...
  • Air Quality Index

    The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. It was created as an easy way to correlate levels of different pollutants to one scale; the higher the AQI value, the greater the health concern. When levels of ozone and/or fine particles are expected to exceed an AQI value of 100, an Air Quality Health Advisory is issued alerting sensitive groups to take the necessary precautions.


    Air Quality Index (AQI) Values

    Levels of Health Concern

    Cautionary Statement

    When the AQI is in this range...

    ...air quality conditions are:

    ...according to Air Quality level

    0 to 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk.
    51 to 100 Moderate Air quality is acceptable, however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
    101 to 150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected.
    151 to 200 Unhealthy Everyone may begin to experience health effects, members of sensitive groups may experience more serious health effects.
    201 to 300 Very Unhealthy Health alert: everyone may experience more serious health effects.
    301 to 500 Hazardous Health Warnings of emergency conditions. The entire population is more likely to be affected.

    Source: EPA




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    Fine Particles

    Fine Particle pollution (also known as "fine particles") in the air includes a mixture of solids and liquid droplets. Some particles are emitted directly; others are formed in the atmosphere when other pollutants react. Particles come in a wide range of sizes. Those less than 2.5 micrometers in diameter are so small that they can get into the lungs, potentially causing serious health problems. 2.5 micrometers is 1/7th the width of a single human hair.


    AQI Values

    Levels of Health Concern

    Cautionary Statements

    0 to 50 Good None.
    51 to 100 Moderate Unusually sensitive people should consider reducing prolonged or heavy exertion.
    101 to 150 Unhealthy for Sensitive Groups People with heart or lung disease, older adults, and children should reduce prolonged or heavy exertion.
    151 to 200 Unhealthy People with heart or lung disease, older adults, and children should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion.
    201 to 300 Very Unhealthy People with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion.
    301 to 500 Hazardous People with heart or lung disease, older adults, and children should remain indoors and keep activity levels low. Everyone else should avoid all physical activity outdoors.

    Source: EPA




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    Ozone

    Ozone is a gas composed of three atoms of oxygen. Ozone occurs both in the Earth's upper atmosphere and at ground level. Ozone can be good or bad, depending on where it's found.

    GOOD OZONE

    Ozone occurs naturally in the Earth's upper atmosphere 6 to 30 miles above the Earth's surface where it forms a protective layer that shields us from the sun's harmful ultraviolet rays. This beneficial ozone is gradually being destroyed by man-made chemicals. An area where the protective ozone layer has been significantly depleted for example, over the North or South pole's sometimes called the ozone hole.

    BAD OZONE

    In the Earth's lower atmosphere, near ground level, ozone is formed when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight. Ozone at ground level is a harmful air pollutant.


    AQI Values

    Levels of Health Concern

    Cautionary Statements

    0 to 50 Good None.
    51 to 100 Moderate Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors.
    101 to 150 Unhealthy for Sensitive Groups Active Children and adults, and people with lung disease, such as asthma, should reduce prolonged or heavy exertion outdoors.
    151 to 200 Unhealthy Active children and adults, and people with lung disease, such as asthma, should avoid prolonged or heavy exertion outdoors. Everyone else, especially children, should reduce prolonged or heavy exertion outdoors.
    201 to 300 Very Unhealthy Active children and adults, and people with lung disease, such as asthma, should avoid all outdoor exertion. Everyone else, especially children, should avoid prolonged or heavy exertion outdoors.
    301 to 500 Hazardous Everyone should avoid all physical activity outdoors.

    Source: EPA




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    More Information

    EPA Websiteleaves DEC's web site

    NYS Air Monitoring Website

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