Singapore's western region not in unhealthy, very unhealthy PSI range for first time since Oct 5
On the 18th day after air quality first entered the unhealthy and very unhealthy ranges in western Singapore, the 24-hour Pollutant Standards Index (PSI) there has finally returned to the good-to-moderate range.Amid a spike in the number of hotspots — from 175 to 522 — in Kalimantan on Oct 4, Singapore has been recording PSI in the unhealthy to very unhealthy ranges since Oct 5.And while hourly PM2.5 and PSI readings began improving in parts of the country from Oct 18, the western region continued to be an outlier due to the prevailing winds that brought in smoke haze from southern Sumatra.The highest 24-hour PSI reading this haze season was 230 in the western region, recorded at 10am and 11am on Oct 18.At 3pm on Thursday (Oct 22), the western PSI reading was in the moderate range (99), while its hourly PM2.5 readings was in the normal band (39µg/m3).