Hazy skies expected sporadically today

SINGAPORE — While the smoggy conditions that persisted overnight from Saturday eased yesterday morning, hazy skies are still expected sporadically today, the National Environment Agency (NEA) said in its advisory yesterday evening.

Prevailing winds are forecast to be light and variable in direction today, which could blow in haze from the region from time to time, it said. The overall 24-hour Pollutant Standards Index (PSI) is expected to remain in the high end of the moderate range and the low end of the unhealthy range today, with thundery showers projected in the afternoon.

PSI readings between 50 and 100 fall under the moderate air quality band. Anything above that up to 200 is considered unhealthy air quality.

At 7pm, the one-hour concentrations of PM2.5 air pollutants — tiny particles smaller than 2.5 microns in diameter — were 28 to 42 ug/m3.

For the most of yesterday, air quality hovered in or close to the unhealthy range. A change in the prevailing wind direction and showers over parts of Singapore in the late afternoon saw the 24-hour PSI dip just into the moderate range of 86 to 99 as at 7pm.

Between 9am and 10am, however, that reading was as high as 92 to 105. The last time the 24-hour PSI persisted in the moderate to unhealthy range was on Oct 7, when it hit a high of 107-125 at 9am.

Given the air quality forecast for the next 24 hours, the NEA said healthy people 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. Joy Fang