What is AQI?

Air Quality Index (AQI) is a number used to communicate how polluted the air is. As the AQI increases, a higher percentage of the population is likely to experience negative health effects.

Different countries have their own air quality indices, corresponding to different national air quality standards. The scale used in the Blueair Friend app is based on the Environmental Protection Agency's scale. This AQI is divided into six categories indicating increasing levels of health concern. An AQI value over 300 represents hazardous air quality. Below 50 means the air quality is good.