The ambient air quality measurement in Malaysia is described in terms of Air Pollutant Index (API). The API is developed in easily understood ranges of values as a means of reporting the quality of air instead of using the actual concentration of air pollutants. This index also reflects its effect on human health ranging from good to hazardous and also can be categorized according to the action criteria as stipulated in the National Haze Action Plan. The Malaysian API system closely follows the Pollutant Standard Index (PSI) developed by the United States Environmental Protection Agency (US-EPA)1.

The air pollutant index scale and terms used in describing the air quality levels are as in figure 1.

https://www.doe.gov.my/portalv1/en/info-umum/english-air-pollutant-index-api/100