FAQs on the Haze June 20 2013
Q1) What is PSI?
PSI stands for 'Pollutant Standards Index'. It is an index developed by the United States Environmental Protection Agency (USEPA) to provide accurate, timely and easily understandable information about daily levels of air pollution.
The ambient air in Singapore is monitored through a telemetric network of air monitoring stations strategically located in different parts of Singapore.
Air pollutants such as sulphur dioxide, nitrogen dioxide, ozone, carbon monoxide and particulate matter called PM10 (particulate matter of 10 microns or smaller in size) are used in the determination of the index.
The PSI value gives an indication of the air quality as shown:
PSI Value |
PSI Descriptor |
| 0 to 50 | Good |
| 51 to 100 | Moderate |
| 101 to 200 | Unhealthy |
| 201 to 300 | Very unhealthy |
| Above 300 | Hazardous |
Q2) How are the 5 regions (north, south, east west and central) for PSI determined?
Region |
Town Centres |
| North | Kranji, Woodlands, Sembawang, Yishun, Seletar and Punggol |
| South | Holland, Queenstown, Pasir Panjang, Sentosa and City |
| East | Serangoon, Hougang, Pasir Ris, Tampines, Kallang, Katong, Macpherson, Bedok, Pulau Ubin and Pulau Tekong |
| West | Lim Chu Kang, Choa Chu Kang, Tuas, Jurong East, Jurong West, Jurong Industrial Estate, Bukit Batok, Ulu Pandan, West Coast and Clementi |
| Central | Bukit Panjang, Pierce Reservoir, Ang Mo Kio, Bishan, MacRitchie, Toa Payoh and Bukit Timah |
Q3) Where can I get the latest PSI in Singapore?
