Also referred to as air quality index (AQI). This is a measure of different levels of concentration of air pollutants in the air. This index by another name was originally established in 1976. With each pollutant level, there is a warning depending on the concentration and its effects to the public. Alert levels can be found for any of five pollutants and the levels have colour and number indicators that warn the public. The pollutants upon which the air quality index is based are ground-level ozone, particulate matter, carbon monoxide, sulphur dioxide, and nitrogen dioxide. The AQI levels are:

(>301) Maroon = Hazardous

(201-300) Purple = Very Unhealthy

(151-200) Red = Unhealthy

(101-150) Orange = Unhealthy for Sensitive Groups

(51-100) Yellow = Moderate

(0-50) Green = Good.