Climate & Environment

Singapore Air Quality Rises to Unhealthy Levels Across Entire Island

By Daniel Lai

The 24‑hour PSI in southern Singapore reached 101 at midday on Oct. 6, placing the whole island in the unhealthy range. By 5 pm, PSI readings in all regions remained between 102 and 135. The PSI, a rolling average of six key pollutants, is considered unhealthy when it falls between 101 and 200. PM2.5 levels, which indicate immediate air quality, were elevated in the south, east, west and central regions at midday and crossed into the elevated band at 4 pm. At 5 pm, hourly PM2.5 readings ranged from 73 to 103; a range of 56 to 150 denotes elevated fine‑particle concentrations. Between 9 pm and midnight on Oct. 4, the entire island was shrouded in unhealthy air, peaking at a PSI of 136 in the central region. Only the central and west regions have remained in the unhealthy band for at least 24 hours. In its Oct. 5 haze advisory, the National Environment Agency forecast a “high moderate to mid unhealthy” 24‑hour PSI, citing prevailing south‑east or east‑south‑east winds and dry conditions over Kalimantan and southern Sumatra, where moderate to dense smoke plumes drift toward Singapore. The PSI entered the unhealthy range four weeks earlier, hitting 101 in central Singapore on Sept. 4, and the highest reading of the year—164 in central Singapore—was recorded on Sept. 29. These September readings mark the first time since October 2023 that Singapore’s PSI has reached unhealthy levels due to haze. Authorities had warned of haze risk between June and October because of warmer, drier conditions from El Niño and the Indian Ocean Dipole. Experts predict that the 2026 “Godzilla” El Niño event could extend the haze period by reducing rainfall and raising temperatures in October‑November. In non‑El Niño years, the dry south‑west monsoon usually ends by September and the rainy north‑east monsoon begins in late November. The Meteorological Service Singapore told The Straits Times that strong El Niño events tend to delay the end of the dry season in southern ASEAN, with a transition expected only in late October or early November for Singapore, later than in the previous two years.