COG, in partnership with the District Department of Energy & Environment, Maryland Department of the Environment, and Virginia Department of Environmental Quality, provides daily air quality forecasts for the metropolitan Washington region. Forecasts are available year-round and are based on the national Air Quality Index.
The Air Quality Index (AQI) is a national index for reporting forecasted and daily air quality. It explains how clean or polluted the air is, and highlights associated health concerns. The AQI focuses on health effects that can happen within a few hours or days after breathing polluted air. It is divided into several color-coded categories, which correspond to different levels of health concerns.
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Air Quality Index
Levels of Health Concern
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Numerical
Value
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Meaning
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Good
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0-50
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Air quality is considered good, and air pollution poses little or no risk.
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Moderate
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51-100
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Air quality may pose a moderate health risk, especially for those who are unusually sensitive to air pollution.
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Unhealthy for
Sensitive Groups
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101-150
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Members of sensitive groups, children and adults with respiratory and heart ailments, may experience health effects and should limit time spent outside. The general public is not likely to be affected.
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Unhealthy
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151-200
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Everyone may experience health effects and should limit their outdoor activity; members of sensitive groups may experience more serious health effects.
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Very Unhealthy
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201-300
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Everyone may experience more serious health effects and should avoid outdoor activities, especially individuals with heart and breathing ailments, children, and older adults.
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Additional Air Quality Resources: