Is the Pollutant Standards Index (PSI) an effective measure of air quality here? That was a question some netizens posed as the haze worsened yesterday.
Several, like Mr Phil Askey, have noted that the PSI does not factor in fine particles called PM2.5. They believe this means the PSI is not a good reflection of air quality here.
PM2.5 particles, about one-thirtieth the width of a human hair, are more dangerous as they can enter the lungs or bloodstream more easily than larger dust particles.
He said the Air Quality Index (AQI), for instance, takes into account PM2.5 concentrations.
There is no international consensus on air-quality indexes.The PSI was developed by the United States Environmental Protection Agency, but the US switched to the AQI in 1999
In a report by The Straits Times in 2010, the NEA said it was studying other indexes that measure air quality.
NEA had said that the PSI has served Singapore well when it comes to issuing health advisories to the public.
NEA also noted then that the public has become used to the PSI over the years. Full story
