Air quality ‘unhealthy’: 3-hour PSI level reaches 153 at 7pm

SINGAPORE – Air quality entered the unhealthy range today (Oct 6), with the three-hour Pollutant Standards Index (PSI) reaching 153 at 7pm, the highest in the latest bout of haze to hit Singapore in recent weeks.

The three-hour PSI crept upwards steadily from the morning, rising from the mid-50s to 88 at noon, first breaching the unhealthy level at 1pm. The 3-hour PSI then continued rising. At 8pm, the three-hour PSI was at 149. The 24-hour PSI at 8pm for overall Singapore was 83-94.

In an update at 8pm, the National Environment Agency (NEA) said the PM2.5 levels are elevated in all regions of Singapore, with the one-hour concentrations of PM2.5 rising to 131μg/m3 in the southern region of Singapore. "The haziness was due to smoke haze blown in from central Sumatra by the prevailing southwesterly winds," said the NEA. Earlier on today, the NEA noted the "significant deterioration in the air quality in most regions of Singapore".

A total of 97 and 74 hotspots were detected in Sumatra and Kalimantan, respectively, today. Smoke haze from central Sumatra continued to be blown by the prevailing winds across the Straits of Malacca towards Singapore and the southern part of Peninsular Malaysia. Widespread smoke haze is also visible in the southern and eastern parts of Kalimantan.

The NEA said it "has requested the Indonesian authorities for an urgent update on the ground situation in Sumatra, and to take immediate action to suppress the fires".

Hazy conditions in Singapore are expected to persist overnight. For tomorrow, the prevailing winds are forecast to blow from the south or south-west, and hazy conditions can still be expected for Singapore. The overall air quality for the next 24 hours is expected to be in the unhealthy range.

The NEA advised that given the air quality forecast for tomorrow, healthy persons should reduce prolonged or strenuous outdoor physical exertion. The elderly, pregnant women and children should minimise prolonged or strenuous outdoor physical exertion, while those with chronic lung or heart disease should avoid prolonged or strenuous outdoor physical exertion. Persons who are not feeling well, especially the elderly and children, and those with chronic heart or lung conditions, should seek medical attention.

A PSI reading of 101 to 200 falls within the unhealthy range, while a 51 to 100 reading is considered moderate.

Facebook user Davy Devaraj said the air at upper thomson has a "strong burning smell", while Twitter user @1RSingapore said a there was a "strong burning smell" in the air at Yew Tee at about 2.50pm. Twitter user @isnani said the haze is " very bad today. You can see it. You can smell it."