Haze in Singapore: Air quality at unhealthy range in three regions

Haze in Singapore: Air quality at unhealthy range in three regions Air quality in parts of Singapore on Saturday (Sep 5) started the day in the unhealthy range, with the 24-hour Pollutant Standards Index (PSI) at 120 in the central region at 6am SINGAPORE: Air quality in parts of Singapore on Saturday (Sep 5) started the day in the unhealthy range, with the 24-hour Pollutant Standards Index (PSI) at 120 in the central region at 6am, according to the National Environment Agency (NEA). The 24-hour PSI crossed into the unhealthy band of 101 to 200 at 7am on Friday, marking the first time the PSI had breached the level since Oct 8, 2023. This prompted the NEA on Friday to start issuing daily haze advisories, including a 24-hour PSI forecast, to help the public plan activities and events for the following day. In the first daily advisory on Friday evening, NEA said Singapore could continue to be affected by transboundary haze, with the 24-hour PSI forecast to be at the higher end of the moderate to the middle of the unhealthy range. As of 6am on Saturday, the PSI in the west was also in the unhealthy range at 103, while the eastern region had a reading of 102. The other regions remained in the moderate range, with the PSI at 86 in the north and 88 in the south. 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. In an earlier joint media release issued on behalf of agencies in the Haze Task Force (HTF), NEA said those in the task force have implemented their respective action plans and advisories to protect public health and well-being. NEA's daily haze advisories will include the 24-hour PSI forecast, which can be used by the public to plan their activities and events for the next 24 hours.