22 October 2015

A Walk In The Haze

Monday (19 October) was an evening to remember.

My friends and I attended a function in the western part of Singapore. When we entered the air-conditioned room, the latest (i.e., 7 pm) 24-hour PSI (west) was 125, the 3-hour PSI was 77 and the 1-hour PM2.5 (west) was 48 micrograms per cubic metre (equivalent to a 1-hour PSI of 91).

When the function ended two hours later, we found the air outdoors thick with haze.

16 October 2015

NEA's Stubborn Refusal To Publish 1-Hour PSI

National Environmental Agency ("NEA") has rejected calls to publish the 1-hour PSI, explaining as follows:

"Since April [2014], the 24-hour Pollutant Standards Index (PSI), three-hour PSI and one-hour PM2.5 concentrations have been published hourly, on the hour, on the NEA website ….

The scale used to convert PM2.5 concentrations to the PSI has been derived based on health studies of exposure over a 24-hour period. This is why the NEA uses the 24-hour average concentrations to compute the PSI.