The air quality in Malaysia is reported as the API (Air Pollutant Index) or in Malay as IPU (Indeks Pencemaran Udara). Four of the index's pollutant components (i.e., carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide) are reported in ppmv but PM2.5 particulate matter is reported in g/m3
If the API exceeds 500, a state of emergency is declared in the reporting area. Usually, this means that non-essential government services are suspended, and all ports in the affected area are closed. There may also be a prohibition on private sector commercial and industrial activities in the reporting area excluding the food sector.