Air quality in Singapore has deteriorated over the last two days, with winds from the north-east and east carrying haze to the city state.
The 24-hour Pollutant Standards Index reached a high of 84 in northern Singapore on Wednesday evening, AsiaOne reported.
Although haze is still moderate, it's exasperated by strong burning smell. This time the haze may not have wafted in from Sumatra in Indonesia, but from Malaysia's Borneo, the reports said.
Early signs of haze cropped up on March 17, but scientists at the National University of Singapore (NUS) had dispelled fears saying burning smell might have come from Singapore's own backyard.
Last year, PSI levels, the measure of air quality, rose above 300, levels seen as quite hazardous.
Meanwhile, the SDF said it extinguished as many as 20 vegetation fires in a single day on Tuesday, but most of these were relatively minor.
Erik Velasco, a research scientist from the Singapore-MIT Alliance for Research and Technology, said the haze hazard could get worse later in the year.
"Because of the magnitude of El Nino this year, we must be prepared for a new period of intense haze similar to last year's, once the winds start blowing from the south and south-west, bringing plumes from Sumatra and Kalimantan," she said, according to AsiaOne.
Earlier this month officials said Singapore suffered losses of about S$700 million due to large-scale haze that enveloped the city state during 2015.
Environment and Water Resources Minister Masagos Zulkifli said greater bilateral cooperation was required to address this annual hazard.
The minister's revelation came even as Indonesia warned that it expects dryer than normal weather this season.
Choking smog drifts off into Singapore and Malaysian cities, sometimes even up to Taiwan and Bangkok, every year as farmers start fires to clear land for palm oil plantations.
Here's a Reuters Factbox that gives a detailed account of the cost of Indonesia fires every year.