An air quality index (AQI) is a measure of the quality of air in the environment which is used by regulatory agencies and governmental authorities to inform the people about the air pollution and the currently and the forecast situation of air pollution of any area. Public health risks correspond to these air quality indices, the risks increase with an increase in AQI. Each country has its own air quality indices depending upon its national air quality standards.
The AQI is a metric for daily air quality monitoring. It shows you how safe or dirty the air is, and what might be a problem for you with related health consequences.
Air quality indices range from 0 to 500. Higher value of AQI refers to the greater degree of air pollution and the greater the risk for humans. For example an AQI value of 50 denotes healthy air quality with no human health risk, whereas a value of 300 and more of AQI demonstrates the more polluted air quality and has harmful effects and greater health risks. The value of 100 of AQI is a standard value that is set by the EPA and is considered as safe value for the public health.