An
air quality index (AQI) is a number used by
government agencies to communicate to the public how
polluted the air currently is or how polluted it is forecast to become. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects. Different countries have their own air quality indices, corresponding to different national air quality standards. Some of these are the
Air Quality Health Index (Canada), the
Air Pollution Index (Malaysia), and the
Pollutant Standards Index (Singapore).