SINGAPORE- The National Environment Agency (NEA) has set out bands and descriptors for hourly PM2.5 readings, to help the public better plan for their activities.
The level of 1-hour PM2.5 concentrations will range from "normal" to "very high".
The range of 0-55 micrograms per metre cube, for instance, will be described as "normal" while anything above 251 micrograms per cubic metre will be described as "very high".
Minister for the Environment and Water Resources Masagos Zulkifli on Monday (June 27) announced the new bands, which are available on the NEA website.
However, the concentration bands will only come with a general guide. The 24-hour Pollutant Standards Index (PSI) reading will still be used by authorities here as the reference for health advisories.
With the introduction of bands and descriptors, the three-hour PSI reading will be phased out by the end of this year.
Mr Masagos made the announcement during a visit to the Metrological Service Singapore's (MSS) headquarters at Changi Airport Terminal 2 on Monday.
PM2.5 is one of six pollutants, which also include ozone, carbon monoxide and sulphur dioxide, that the PSI measures.
PM2.5 pollutants are smaller than 2.5 microns in diameter, or a 30th the diameter of a human hair, and the body is not equipped to filter them out, unlike coarser particles.
Long-term exposure to them on a regular basis has been linked to increased risk of death from complications such as lung cancer or heart disease.
While there have been recent studies on shorter PM2.5 exposure, the NEA has said that the results of these studies do not provide enough evidence for developing health advisories for hourly PM2.5 concentration readings.
The NEA will provide additional information on the haze microsite (www.haze.gov.sg) and myENV app on the new bands and descriptors.
During his visit, Mr Masagos viewed a presentation and demonstration of new technologies that improve the monitoring of weather and haze.
For instance, the Himawari-8 satellite - rolled out in July last year - provides updates of haze and weather every 10 minutes compared to hourly updates from the previous satellite MTSAT-2.
An aerosol Lidar (Light Detection and Ranging) surveying system, recently installed on Jurong Island, will also measure the thickness of smoke haze.
It can measure the vertical extent of haze in the atmosphere for heights of up to 12km.