Singapore haze: 1-hour PM2.5 readings in elevated range across all regions

On Friday, October 9, Singapore experienced hazy conditions as PM2.5 readings across all five regions remained in the elevated range during the early morning hours, according to the National Environment Agency (NEA). The 1-hour PM2.5 readings ranged from 92 in the north to 145 in the west, with the central region at 143, the south at 138, and the east at 105.

These readings were notably higher during the early hours before improving by 7am. The 24-hour Pollutant Standard Index (PSI) readings also fell within the unhealthy range, from 111 to 163. The NEA advises those planning outdoor activities to check hourly PM2.5 levels and to reduce strenuous activity for an hour if levels are elevated.

The 24-hour PSI, which measures overall daily air quality, is calculated using six pollutants including PM2.5. When the 1-hour PM2.5 levels are elevated, healthy individuals should limit strenuous outdoor activity for the next hour, while the elderly, pregnant women, children, and those with heart or lung conditions should avoid such activity.

The 24-hour PSI is Singapore's primary indicator of air quality and informs daily health advisories. The PM2.5 pollutant is the primary contributor to haze-related health risks, with a 24-hour PSI of 101-200 considered unhealthy, 201-300 very unhealthy, and above 300 hazardous. The 1-hour PM2.5 reading is classified into four bands, with elevated levels ranging from 56 to 150.

The NEA noted that smoke plumes from southern Sumatra and West Kalimantan were drifting towards Singapore due to dry conditions and prevailing winds, with the 24-hour PSI forecasted to remain in an unhealthy range.