Haze update Sept 18: Singapore air quality moderate; 24-hour PSI forecast in high-moderate to low-unhealthy range
Singapore's air quality remained in the moderate range on Friday (Sept 18).The 24-hour Pollutant Standards Index (PSI) turned unhealthy in central Singapore at 9pm on Thursday night, remaining in that range for about four hours. As at 5pm on Friday, the 24-hour PSI ranged from 64 to 86 — in the moderate range — with central Singapore recording the highest PSI of 86. This was followed by western Singapore, with a PSI reading of 79.Meanwhile, one-hour PM2.5 concentration readings ranged between 31 to 61, in the normal to elevated bands.Central Singapore was the only region in the elevated band, while the other four regions remained in the normal band as at 5pm.The one-hour PM2.5 reading reflects current air quality and should be used when deciding whether to carry out outdoor activities in the next few hours.