Air quality to remain in moderate to low unhealthy range on Wednesday: NEA

Air quality to remain in moderate to low unhealthy range on Wednesday: NEA Moderate to dense smoke plumes continue to be observed from fires in southern and central Sumatra and Kalimantan, said NEA. SINGAPORE: Air quality in Singapore remained in the moderate range on Tuesday (Sep 8), with the National Environment Agency (NEA) forecasting the 24-hour Pollutant Standards Index (PSI) for Wednesday to be in the moderate to low unhealthy range. The 24-hour PSI was between 62 and 74 as at 6pm on Tuesday. In Its health advisory, NEA said that if the air quality over the next 24-hours is in the moderate range, all groups - healthy people, the elderly, pregnant women, children and those with chronic lung or heart disease - can continue with normal activities. If the air quality is unhealthy, healthy individuals should reduce prolonged or strenuous outdoor physical exertion. In such instances, the elderly, pregnant women and children should minimise such activities, and those with chronic lung and heart disease should avoid them altogether. NEA said that moderate to dense smoke plumes continue to be observed from fires in southern and central Sumatra and Kalimantan, with some smoke haze drifting towards Singapore from isolated nearby fires. “With dry conditions expected to persist over southern Sumatra and parts of Kalimantan in the coming days, there remains a risk of smoke haze,” said NEA. NEA added that the health impact of haze depends on a person's health status, the PSI level, and the length and intensity of outdoor activity. It advised the public to check the one-hour PM2.5 concentration readings for immediate outdoor activities, and to use the 24-hour PSI forecast and corresponding health advisories when planning outdoor activities for the next day. NEA began issuing daily haze advisories on Sep 4 after the 24-hour PSI in the central region crossed into the unhealthy band of 101 to 200 at 7am, marking the first time the PSI had breached the level since Oct 8, 2023. Air quality deteriorated steadily throughout the day, with the central, eastern and western regions all recording unhealthy PSI levels by midnight. The 24-hour PSI is Singapore's indicator of daily air quality and forms the basis of NEA's daily health advisories. It is calculated using six air pollutants - PM2.5, PM10, ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide. The 1-hour PM2.5 reading, on the other hand, is the hourly average of the PM2.5 pollutant levels. PM2.5 is fine particulate matter with a diameter of 2.5 micrometres or shorter, and is the dominant pollutant during haze that causes harm to health. While the 24-hour PSI is an average of the past 24 hours, the one-hour PM2.5 reading reflects the air quality at a single point in time. A 24-hour PSI reading is considered "very unhealthy" when it is within the 201-300 range, and "hazardous" when it goes over 300.