Air quality today could worsen from yesterday and is likely to be in the unhealthy range.
In an 8pm statement yesterday, the National Environment Agency (NEA) said that the 24-hour Pollutant Standards Index (PSI) - a measure of air quality here - is forecast to be in the low to mid level of the unhealthy range (101 to 200) today.
The agency warned that it may deteriorate further if the winds are unfavourable.
But yesterday, the 24-hour PSI was mostly in the high end of the moderate range (51-100) and the low end of the unhealthy range.
The 24-hour PSI first crossed into the unhealthy range at 11am yesterday, and at 9pm, it stood at between 91 and 105.
NEA said that yesterday's haze was "due to smoke haze from Sumatra being blown in by the prevailing south-southwesterly winds". For today, the prevailing winds are forecast to blow from the south or south-west, and hazy conditions are expected to persist.
In Sumatra's Riau province yesterday, air quality reached hazardous levels and visibility dropped as low as 100m. Flights were cancelled and schools were closed in Pekanbaru, the provincial capital, and people warned not to venture outdoors, Agence France-Presse reported.
The thick haze came from blazes on western Sumatra island and the Indonesian part of Borneo island, as lands are being cleared by burning down forests.
Indonesian legislator Hamdhani Mukhdar Said, who is in charge of environment and international relations, yesterday apologised to haze-hit Malaysia, saying he would raise the issue with Parliament to urge for more efforts to deal with the haze situation, The Star daily newspaper reported.
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