By Lydia Lam & Tan Tam Mei, The New Paper, The Straits Times,
PHOTO: LIANHE ZAOBAO
Many remain puzzled at the source of the smell and smoke, despite assurances from the National Environment Agency (NEA) and the Singapore Civil Defence Force (SCDF) that there were no toxic industrial substances in the air and air quality had been within safety limits.
From as early as 4pm, residents living in northern areas including Seletar, Yishun and Sengkang started reporting about the acrid smell and the smoke, which spread to central areas such as Bishan around 6pm and to western areas like Clementi around 8pm.
Picture posted by TODAY on 25 September 2017 at 8:31 PMhttps://4.bp.blogspot.com/-MBoTfW1-1a0/WcncBImwByI/AAAAAAAAoFU/KQdc-GT2JNwCxH4k9nBCjIyRNx9DgoRQACLcBGAs/s1600/20170925_smellsengkang.jpg
One of them was Ms Lelavathi Annamali, an Ang Mo Kio Avenue 8 resident, who said she started smelling a "strong kerosene smell" around 6pm and that her home became smoky, which stung her eyes and affected her throat.
"The smell is very bad inside the house and is affecting the clothes too," said the 68-year-old retiree.
Ms Tina Lim, 49, who works in a bank, said there was a "strong burnt smell" when she reached her Sengkang home at 5.30pm.
"It did not smell like haze," she said. "It was like something was burning."
Mr Osman Ahmad, a 59-year-old security guard at Seletar Country Club, told The Straits Times he noticed the smell of burning chemicals when he left his home in Pasir Panjang around 2pm.
When he stopped to transfer buses at Seletar, he noticed the stench was stronger and that people at the bus stop were covering their mouths and noses with tissues and handkerchiefs.
He said: "You could see a layer of smoke on the highway. It looked like a morning fog, which was beautiful but very smelly."
The SCDF and the NEA had deployed officers to investigate upon receiving calls.
In an update at 10.34pm, the NEA said winds converged over the northern half of Singapore from about 3pm, which may have led to smells accumulating in the northern area.
It added that it would continue to monitor the situation closely.
ST understands that the fumes are believed to be from Johor Baru.
 Lydia Lam & Tan Tam Mei, The Straits Times, Strong 'burning' stench worries Singaporeans, posted on 26 September 2017 at 06:00 am, http://www.tnp.sg/news/singapore/strong-burning-stench-worries-singaporeans