SINGAPORE: Air quality across Singapore remained in the good to moderate range on Friday (Oct 22), with the 24-hour Pollutant Standards Index (PSI) readings in all five regions staying within that band.
As of 7am, the PSI readings ranged from 67 to 90.
Air quality across the country returned to the good and moderate level on Thursday after the PSI reading in the west dropped at 3pm.
Readings across all regions were last at this level on Oct 5.
Hourly PM2.5 readings remained within the normal range in all regions at 7am, ranging from 20 to 52.
UNHEALTHY AIR QUALITY FORECAST
On Thursday evening, the National Environment Agency (NEA) said most smoke haze from Kalimantan and Sumatra remained south of Singapore due to northeasterly and easterly winds.
The agency added that it expected the PSI to be in the unhealthy band on Friday, ranging from 101 to 150.
"As dry conditions are expected to persist over the southern parts of Sumatra and Kalimantan, smoke haze may be transported towards Singapore under prevailing southeasterly winds," it said.
Smoke haze might also drift over from Sumatra on Saturday due to expected southeasterly or southerly winds.
"However, showers over Singapore and the vicinity could help with the situation," it said.
NEA added that hazy conditions were expected to improve on Sunday due to showers and favourable winds.
ADVICE FOR VULNERABLE GROUPS
When the 24-hour PSI is in the unhealthy range, NEA advises the elderly, pregnant women and children to minimise prolonged or strenuous outdoor physical exertion.
People with chronic diseases, including heart or lung conditions, should avoid such activities.
For decisions on mask use and immediate outdoor activities, the public should refer to the one-hour PM2.5 readings instead.
When the 1-hour PM2.5 readings are in the high band, vulnerable individuals, including the elderly, pregnant women and those with chronic heart or lung conditions, should avoid outdoor activities, according to the Ministry of Health (MOH).
Those who need to go outdoors for immediate activities may wear a well-fitting N95 mask or equivalent to reduce their exposure to haze particles.
When 1-hour PM2.5 readings reach the very high band of 251 and above, healthy individuals should also minimise all outdoor activities. Those who need to venture outdoors may similarly use an N95 mask for protection.
However, MOH said N95 masks are generally not needed for commuting between home and school or work, or in indoor environments.
The ministry has also advised the elderly, pregnant women and those with severe heart or lung conditions who experience breathing difficulties to consult their doctor before using an N95 mask.
Those who experience discomfort while wearing one should take a break from using it.
Besides N95 masks, KN95, FFP2 and KF94 masks are also effective in reducing exposure to haze particles, according to MOH.
Members of the public can visit the HazeMaskGoWhere website for more information on collection locations and live updates on mask availability at the vending machines.
MOH had also issued guidance on Oct 13 on the types of masks that can be used for protection against haze.
It said surgical masks can help reduce discomfort and the risk of infections by providing a barrier against larger irritant particles.
However, if PM2.5 readings are above 250 and people need to be outdoors for several hours, MOH recommends wearing an N95 or equivalent mask.
Cloth masks generally do not filter fine particles effectively, although they can reduce discomfort by blocking larger irritant particles in the air.