Air quality index


In a number of states, the agency responsible for monitoring air quality reports results at each station in its network in terms of an air quality index (AQI; Box ATM10) for all or some of the pollutants covered by the Air NEPM. The method for assessing ambient air quality in this report is described in Box ATM13.

Box ATM10 Air quality index

An air quality index (AQI) is calculated based on the relevant Air National Environment Protection Measure (NEPM) standard, or advisory standard, for that pollutant as follows:

AQI = pollutant concentration/pollutant standard × 100

This means that, at an index value of 100, the pollutant is currently at a concentration equal to an environmental standard level. The lower the index, the better the air quality.

The AQI provides a number that is easy to compare between different pollutants, locations and time periods. Five qualitative categories are used in public reporting of air quality. The categories and the AQI ranges that they represent are listed in Table ATM5, together with a qualitative description of the associated health effects.

Each category in the AQI corresponds to a different level of air quality and associated health risk.

Table ATM5 Air quality index (AQI)


AQI range


Very good


Air quality is considered very good, and air pollution poses little or no risk



Air quality is considered good, and air pollution poses little or no risk



Air quality is acceptable. However, there may be a health concern for very sensitive people



Air quality is unhealthy for sensitive groups. The general population is not likely to be affected in this range

Very poor


Air quality is unhealthy, and everyone may begin to experience health effects. Sensitive people may experience more serious health effects

Keywood MD, Emmerson KM, Hibberd MF (2016). Ambient air quality: Air quality index. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra,, DOI 10.4226/94/58b65c70bc372