The Malaysian Meteorological Department reported that the air pollutant index (API) recorded at 3pm yesterday showed the levels in Nilai at 112, Seremban 104, Banting 116, Port Klang 135, Putrajaya 107 and Shah Alam 101.
An API reading of between 0 and 50 is considered good, 51 to 100 moderate, 101 to 200 unhealthy, 201 to 300 very unhealthy, and 301 and above hazardous. Unhealthy API levels may lead to chest discomfort, coughs and shortness of breath.
The API readings are calculated based on five major air pollutants: sulphur dioxide (SO2), nitrogen dioxide (NO2), ground level ozone (O3), carbon monoxide (CO) and particulate matter with a diameter below 10 micrometres (PM10).
Most of these pollutants come from various sources such as industries, motor vehicles, open burning and power generation.
The concentrations of these five pollutants are measured in 52 air quality stations throughout Malaysia, mainly located in industrial and urban areas.
A check with the department also showed that except for isolated rain in coastal areas in Sabah, no rain is expected for the peninsula and Sarawak. It has not rained in the Klang Valley in over a week.