Haze watch: Air quality worsens across Singapore, PSI at unhealthy levels in all 5 regions

Air quality in Singapore has deteriorated through Monday (Oct 5) evening, with all five regions recording 24-hour Pollutant Standards Index (PSI) at unhealthy levels.At 9pm, PSI in northern (103) and southern (101) Singapore slipped into the range, after the eastern region entered the unhealthy range at 6pm.PSI readings in central (128), western (125) and eastern (109) Singapore remain in the unhealthy range.Meanwhile, one-hour PM2.5 ranged between 78 and 117, with the central region recording the highest concentration reading.