Haze conditions worsened in Singapore on Monday evening, 5 October, with the eastern region also entering the unhealthy range.
At 6pm, the 24-hour Pollutant Standards Index, or PSI, in the east reached 101. This meant three regions were in the unhealthy band, with the west at 120 and the central region at 122.
The north and south remained in the moderate range, at 94 and 95 respectively.
PM2.5 readings were also elevated across all five regions at 6pm, ranging from 75 in the south to 97 in the central region.
East Joins West and Central Regions
Air quality is considered unhealthy when the 24-hour PSI is between 101 and 200.
Earlier on 5 October, the unhealthy readings were mainly in the central and western parts of Singapore. CNA reported that at noon, the central region had a PSI reading of 117, while the west recorded 108.
By 6pm, the east had crossed into the unhealthy range too, according to The Straits Times’ report based on NEA readings.
The readings at 6pm were:
- North: 94
- South: 95
- East: 101
- West: 120
- Central: 122
The one-hour PM2.5 readings at the same time were:
- North: 77
- South: 75
- East: 79
- West: 79
- Central: 97
For context, PM2.5 refers to fine particles that are 2.5 micrometres or smaller. During haze episodes, this is the main pollutant people are usually concerned about because it can enter the respiratory system more easily than larger particles.
What the Readings Mean
NEA advises the public to use the one-hour PM2.5 reading for immediate outdoor activities, and the 24-hour PSI forecast when planning activities for the next day.
A one-hour PM2.5 reading of 56 to 150 is classified as “elevated”. Since all five regions were within this band at 6pm, people planning outdoor activities should check the latest reading before heading out.
For healthy people, NEA’s haze guidance says that when the 24-hour PSI is in the unhealthy range, they should reduce prolonged or strenuous outdoor physical exertion.
Elderly people, pregnant women and children should minimise prolonged or strenuous outdoor physical exertion. People with chronic heart or lung disease should avoid it.
When the one-hour PM2.5 reading is elevated, healthy people are advised to reduce strenuous outdoor activity for the next hour. Vulnerable groups should avoid strenuous outdoor activity for that period.
Smoke Haze Could Continue
In its 5 October haze update, the Meteorological Service Singapore said dry conditions were observed over Singapore during the day.
As at 6pm, NEA recorded one-hour PM2.5 readings of 75 to 97 micrograms per cubic metre, all in the elevated band. The 24-hour PSI was between 94 and 122, which placed Singapore in the moderate to unhealthy range.
Moderate to dense smoke plumes from southern Sumatra were observed drifting towards Singapore. Smoke haze was also seen from fires in Kalimantan.
Dry conditions were expected to continue over southern Sumatra and Kalimantan. With prevailing winds expected from the south-east or east-south-east, smoke haze could continue to drift towards Singapore.
The 24-hour PSI for Singapore was forecast to be in the high moderate to mid unhealthy range.
In other words, this is not yet the kind of haze situation where you panic-buy masks like it is 2013, but it is definitely the kind where checking myENV before exercising outdoors is a good idea.
