Haze update for Sept 4: 24-hour PSI forecast to be in moderate to unhealthy range

Singapore's 24-hour Pollutant Standard Index (PSI) on Friday (Sept 4) morning entered into the unhealthy range for the first time since Oct 8, 2023, prompting the National Environment Agency (NEA) to begin daily haze advisories.

This includes the 24-hour PSI forecast for members of public to plan their activities and events for the next 24 hours, the agency said in an update just before noon on Friday.

In its first forecast on Friday evening, NEA said dry conditions are expected to continue for the coming days, adding that Singapore may continue to be affected by transboundary haze under the prevailing south-easterly or southerly winds, if the fires in the southern and central parts of Sumatra and various parts of Kalimantan persist.

It also forecast the 24-hour PSI for Singapore to be in the higher end of the moderate to the middle of the unhealthy range. 

Checks on NEA's haze microsite indicate that the 24-hour PSI reading of 116 for the central region remains in the unhealthy range.

Across the north, east, south and west regions, PSI remains in the moderate range, with regions in the east and west having readings of 98 and 95 respectively — that borders the unhealthy range.

General advisory

NEA said that the health impact of haze is dependent on one's health status, the PSI level, and the length and intensity of outdoor activity. 

It advised those who are immediately planning to conduct or participate in outdoor activities to check the 1-hour PM2.5 concentration readings and person guide.

Meanwhile, those who are planning for outdoor activities for the next day should use the 24-hour PSI forecast and the corresponding health advisories for planning.

Category-based advisory 

Based on the 24-hour-PSI forecast on Friday, healthy persons can continue with normal activities if PSI remains in the moderate range. 

However, they should reduce prolonged or strenuous outdoor physical exertion if PSI crosses into the unhealthy range.

Elderly persons, pregnant women and children can also continue with normal activities if the PSI remains in the moderate range. 

They should minimise prolonged or strenuous outdoor physical exertion if the PSI is in the unhealthy range.

Those with chronic lung or heart disease may similarly continue with normal activities when the PSI is moderate. 

But they should avoid prolonged or strenuous outdoor physical exertion if the PSI reading crosses into the unhealthy range.

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