Bands will help public interpret readings better, says NEA, three-hour PSI to be phased out
From Monday (June 27), one-hour readings of fine particulate matter, or PM2.5, will come with bands indicating if levels are normal, elevated, high or very high.
This is to help the public to interpret one-hour PM2.5 better, and to plan their immediate activities.
Under the new banding, one-hour PM2.5 concentrations of 55 micrograms per cubic metre and below are “normal”; readings of 56 to 150 are “elevated”; readings of 151 to 250 are “high”; and anything above 250 is “very high”.
But the one-hour readings are not tied to health advisories, which apply only to 24-hour Pollutant Standards Index (PSI) readings because studies on sub-daily PM2.5 exposure still do not provide a sufficient evidence base, said the National Environment Agency (NEA).
The 24-hour PSI forecast will also continue to be used for major decisions such as the closure of schools.
The one-hour PM2.5 readings will come with a general guide stating that each person’s reaction to pollutants may vary. Hence, the level of physical activity should be according to one’s health status and those with chronic heart or lung diseases should have medication handy. Healthy individuals exposed to high levels of haze particles may get irritation of the eyes, nose and throat.
Although the PSI includes other pollutants like sulphur dioxide and carbon monoxide, PM2.5 is the air pollutant of concern during haze episodes. The highest one-hour PM2.5 recorded in Singapore last year was 471 on Oct 19, when the region was affected by forest and plantation fires raging in Indonesia.
With the introduction of bands for one-hour PM2.5, the NEA will do away with three-hour PSI readings as they will “no longer be relevant”. They will be phased out by the end of the year.
The haze microsite, www.haze.gov.sg, and NEA’s myENV app will feature the new one-hour PM2.5 bands.