SINGAPORE - The air quality in Singapore has dropped into the 'moderate' range, as the Pollutant Standards Index (PSI) rose into the 52 to 59 range this morning.
The highest PSI levels were recorded in the north and east.
At 8am today, the the 24-hour PM2.5 level - which is the measure of very fine particles in the air - ranged from 51 micrograms per cubic m in the north to 39 in the south.
As these very fine particles are more hazardous to the health as they are better able to penetrate the lungs and bloodstream, a range of 40 to 65 carries a health advisory from the National Environment Agency (NEA).
NEA warned residents living in the north, east, west and central to limit prolonged or heavy outdoor exertion, especially those suffering from heart or lung disease, children and the elderly.
Singapore's PSI hit a one-year high of 79 on Sept 7.
NEA warned that periodic hazy conditions are expected to continue due to an increase in hotspot activities combined with the low level winds blowing from the southeast or southwest.
The annual haze is typically caused by farmers and logging companies burning forest areas to clear land for cultivation.
The wind blowing from these countries brings the smoke to Singapore.
The impact of the smoke haze in Singapore 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 rain.