Singapore's central region returns to unhealthy air quality as Sumatra and Kalimantan fires send haze

Air quality in central Singapore re-entered the unhealthy range at 9pm on 4 October 2026, with the 24-hour Pollutant Standards Index (PSI) in the central region reaching 101; other regions — east (82), west (83), south (76), north (78) — remained at moderate levels. The National Environment Agency said moderate to dense smoke plumes from southern Sumatra continued to drift toward Singapore, with additional smoke observed from fires in Kalimantan. The 24-hour PSI forecast was for the high moderate to low unhealthy range on Monday, with dry weather expected to persist.