Air Quality Index

What is Air Quality Index (AQI):

The AQI is a tool for reporting daily air quality of any city or country. It tells how clean or polluted the air is, and what associated health effects might be a concern for public. The AQI focuses on health effects that one might experience within a few hours or days after breathing polluted air.

How Does the AQI Work?

Think of the AQI value as a yardstick (table) that runs from 0 to 500.The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI of 50 represents good air quality with little potential to affect public health, while an AQI value of 300 represents hazardous air quality.

An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the level that set by the mandated Environment Protection Agency (e.g., for Bangladesh Department of Environment) to protect public health. AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy-at first for certain sensitive groups of people, then for everyone as AQI values get higher.

Purpose of AQI

  • Daily release of air quality conditions to the public
  • Convey the health implications of air quality
  • Protect public interest and take actions to reduce emissions
  • Forecast air pollution level

In Bangladesh the AQI is based on 5 criteria pollutants; Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone (O3). The Department of Environment (DoE) has also set national ambient air quality standards for these pollutants. These standards aim to protect against adverse human health impacts. The AQI standard for Bangladesh is given as under.
Approved Air Quality Index (AQI) for Bangladesh

other monitors located in the same cities.

Air Quality
Index Levels
Numerical Value Meaning
Good 0 to 50Air quality is considered satisfactory, and air pollution poses little or no risk
Moderate 51 to 100Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Unhealthy for Sensitive Groups101 to 150 Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Unhealthy151 to 200Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
Very Unhealthy 201 to 300Health warnings of emergency conditions. The entire population is more likely to be affected.
Hazardous301 to 500Health alert: everyone may experience more serious health effects.