Haze update Sept 17: Singapore air quality remains moderate, 24-hour PSI forecast to reach low unhealthy levels

Singapore’s air quality remained in the moderate range on Thursday (Sept 17), extending the improvement in conditions seen since Wednesday afternoon.Data from the National Environment Agency (NEA) shows that the 24-hour Pollutant Standards Index (PSI) at 6pm stood between 68 and 95 at 6pm — in the moderate range — with the highest reading of 95 recorded in central Singapore.AsiaOne’s checks on the 24-hour PSI hourly data show that air quality in central Singapore had been gradually deteriorating since 8am, with PSI readings edging closer to the unhealthy threshold.Meanwhile, one-hour PM2.5 concentration readings were in the elevated band for three regions at 6pm — central (99), western (66) and southern (58) Singapore. The two remaining regions recorded one-hour PM2.5 readings in the normal band.In its daily haze situation update on Thursday evening, NEA said Singapore’s 24-hour PSI is forecast to be in the high moderate to low unhealthy range.Explaining this, NEA said smoke haze was observed to have drifted from southern and central Sumatra towards Singapore during its weather satellite pass at 2.17pm.