Haze watch: PSI enters unhealthy range in central, western Singapore

Barely a day after 24-hour Pollutant Standards Index (PSI) returned to the moderate range on Sunday morning, air quality again deteriorated overnight. PSI in central Singapore entered the unhealthy range at 1am on Monday (Oct 5) morning, with the western region following suit at 6am.At 8am, PSI readings in northern (85), southern (87), and eastern (91) Singapore are in the moderate range, while the central (113) and western (104) regions recorded unhealthy readings.Meanwhile, one-hour PM2.5 is also in the elevated band in central (83) and western (58) Singapore, but concentration readings in the northern, eastern and southern regions are in the normal band.In its daily haze situation update on Sunday evening, the National Environment Agency said the country's 24-hour PSI is expected to be in the high-moderate to low-unhealthy range.