air quality index (AQI), an online, color-coded index created by the U.S. Environmental Protection Agency (EPA) that communicates whether the relative air quality and air pollution level in a given area is healthy or unhealthy. Maps of local AQI values are updated every 8 or 24 hours, depending on the pollutant, and provide an indication of the groups of people most likely to be affected by current air conditions. Many countries worldwide utilize the U.S. AQI standards to report local air quality. The AQI was first released by the United States government in 1999, though the EPA had been tracking ...(100 of 394 words) Access the full article Help support true facts by becoming a member. Subscribe today!