Woo Sian Boon Today Online 24 Apr 13;
SINGAPORE — Hourly updates of the haze situation here are now being made available by the National Environment Agency (NEA) — more than a month ahead of the traditional dry season when the region’s burning activities are more pronounced. The service, which began yesterday, comes after forest fires in Sumatra over the past few days.
Air quality remained good yesterday, as the three-hourly Pollutant Standards Index (PSI) readings between 7am and 7pm fluctuated between 40 and 46, reaching the peak at 2pm. As at 7pm, the reading was 44. Readings below 50 are classified as “good”, higher than 50 is “moderate” while anything above 100 is “unhealthy”. The level of PM2.5, or very fine particulate matter, was between 24 to 28 micrograms per cubic metre, yesterday.
Although air quality has mostly remained good since the beginning of this year, the smoggy conditions and burning smell experienced across the island last Friday led to many concerns that the haze was back.
According to the NEA yesterday, Singapore is “unlikely to be affected by significant trans-boundary haze” as the increase in rainfall over the last few days which has “helped to suppress hotspot activities” is expected to continue “for the next few days”. However, it added that “brief slight haziness” is possible, especially during the mornings. “This is due to the accumulation of particulate matter and/or mist as the low-level winds are forecast to be light and variable,” said the agency.
The NEA also said that while the region’s burning activities occur throughout the year, these will be more pronounced during the traditional dry season, which typically lasts between June and October.
While the severity and duration of the dry season varies from year to year, it is characterised by prevailing winds that generally blow from the south-east and south-west.
“During periods of dry weather conditions, increased burning activities tend to occur in the region and the smoke haze from these fires can be carried over to Singapore by prevailing winds,” said the NEA.
It added that the impact of the haze is dependent on factors such as the proximity and extent of the fires, the strength and direction of the prevailing winds, and the incidence and amount of rainfall.
Given the recent forest fires in Sumatra, and in order to provide the public with timely information about the haze, the NEA has decided that it would make available three-hour PSI readings on its website and smart phone application starting yesterday.
The three-hour PSI readings will be updated from 7am to 7pm daily.
