Air Quality Index
Air Quality Index
The Air Quality Index (AQI) is a numerical scale used for reporting daily air quality. It provides a standardized public health-based index for reporting air quality.
Pronunciation
- IPA: /ɛər kwɒlɪti ɪndɛks/
Etymology
The term "Air Quality Index" is derived from the English language. "Air" comes from the Old English ǣr, "Quality" comes from the Latin qualitas, and "Index" comes from the Latin index, meaning 'pointer' or 'indicator'.
Definition
The AQI focuses on health effects that may be experienced within a few hours or days after breathing polluted air. It uses a set of air quality standards, established by environmental health agencies, for five major air pollutants regulated by the Clean Air Act. These pollutants are ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide.
Related Terms
Calculation
The AQI is calculated for each pollutant separately. Each AQI value is then compared and the highest is reported as the AQI for that day. The higher the AQI value, the greater the level of air pollution and the greater the health concern.
Health Implications
An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the level EPA has set to protect public health. AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy, at first for certain sensitive groups of people, then for everyone as AQI values get higher.
See Also
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