According to my mother, it was reported in the Singapore media that a strange smell was detected in Punggol. It was believed to have originated from southern Johor.
Just now, I was at a party at a relative's place. He had invited a friend along. This friend works at a plastics plant in Pasir Gudang. When I mentioned the strange smell over Punggol, he straightaway said his workplace was responsible.
So Punggolites, get your act together. Lodge a complaint about air pollution by a foreign entity. Remember the haze from Indonesia? As long as the wind blows in your direction, the pollutants will come your way.
Hougang and Sengkang also can smell. Especially those facing North, Northeast. Situation get worse during the NE monsoon period where the winds blow from Malaysia into Singapore.