Measure PSI at different altitudes

The National Environment Agency (NEA) publishes Pollutant Standards Index (PSI) readings horizontally across various regions of the island. But at what altitude is the PSI measured?

Smoke and haze rise, hence, the PSI at ground level, on the road and at the park can be substantially different from that at a rooftop garden cafe at a high-rise hotel.

Singapore is densely populated with high-rise buildings. There are HDB flats that are 40 storeys high. HDB has also built roof gardens above multi-storey carparks.

Condominiums and Design, Build and Sell Scheme apartments have open balconies. Penthouse open roofs are common, too.

Open-air dining at high-rise hotels is popular here.

Hence, if the PSI is measured at ground level to be marginally safe, it may be at a hazardous level on top of tall buildings.

Could the NEA provide PSI readings at average altitudes for normal activities, as well as at higher altitudes for high-rise living and activities?

Aaron Ang Chin Guan

A version of this article appeared in the print edition of The Straits Times on October 24, 2015, with the headline 'Measure PSI at different altitudes'. Print Edition | Subscribe