Singapore haze remains unhealthy despite showers, with PSI forecast to hit 220

The PSI shows how polluted Singapore’s air is over a 24-hour period. Today’s readings ranged from 130 in northern Singapore to 199 in the west, placing the island in the unhealthy range. The forecast of 150 to 220 means unhealthy conditions are expected to continue, with some areas possibly entering the very unhealthy range.

The western region reached a PSI of 199, just below the very unhealthy threshold. Hourly PM2.5 also reached 243 micrograms per cubic metre at 2pm, although showers may have prevented it from exceeding 251, the very high band threshold. This shows that short-term pollution was also severe.

The outlook is mixed. Showers and shifting winds may reduce smoke arriving from Kalimantan, but haze from Sumatra may still drift towards Singapore. More showers are expected early next week, while weakening southeast or southerly winds could further reduce Kalimantan smoke transport.

The Pollutant Standards Index, or PSI, converts several air-pollution measurements into one number describing overall air quality. It helps the public understand whether outdoor conditions are relatively safe or potentially harmful. In this article, Singapore’s 24-hour PSI is unhealthy, and tomorrow’s forecast may reach the very unhealthy range.

On the commonly used PSI scale, 101 to 200 is unhealthy, while 201 to 300 is very unhealthy. A PSI of 199 is therefore at the top of the unhealthy band. A forecast of 220 would fall into the very unhealthy band. These categories describe increasing concern, rather than measuring the amount of smoke alone.

Unhealthy air can aggravate breathing and heart problems, especially for sensitive people. Very unhealthy air presents a broader public-health concern. The article reports PSI values from 130 to 199 today and advises people to check current PM2.5 readings before outdoor activities.

The reported pollution is high by Singapore’s PSI categories. Today’s 24-hour PSI ranged from 130 in northern Singapore to 199 in the western region. Under the commonly used scale, both are unhealthy, with 199 near the upper edge of that band. The forecast range of 150 to 220 indicates continued unhealthy air and possible very unhealthy conditions.

The hourly PM2.5 readings show how sharply pollution can change during a day. In the west, the concentration rose from 111 to 158µg/m3 at 11am, then reached 243µg/m3 at 2pm. Showers may have kept it below the very high hourly band, defined in the article as above 251µg/m3.

A PSI of 199 is not 199 percent pollution, nor is 220 a concentration measurement. They are index values. A forecast of 220 crosses from unhealthy into very unhealthy, so people should follow updated readings and limit exposure when pollution is high.

Unhealthy and very unhealthy haze means people may breathe air containing elevated pollution. Exposure can irritate the eyes, nose, throat, and lungs. It can also worsen coughing, asthma, and other existing breathing conditions. People with heart or lung disease, older adults, children, and pregnant people may be more sensitive. These health effects are established guidance; the article itself does not list specific symptoms.

The article reports western hourly PM2.5 reaching 243µg/m3 and a 24-hour PSI as high as 199. Such readings indicate that outdoor air contains substantial pollution. During outdoor exercise, people usually breathe more deeply and rapidly, so they may take in more polluted air than when resting indoors.

Limiting outdoor activities lowers exposure while conditions are poor. People should check the latest PM2.5 readings before going outside, as the article advises. Showers may temporarily reduce airborne pollution, but smoke from Kalimantan and Sumatra can continue drifting towards Singapore.

Showers can temporarily improve air quality by removing some suspended particles from the atmosphere. Raindrops capture particles as they fall, and wet conditions can also help settle particles onto surfaces. This does not extinguish distant fires or remove every particle, so pollution can return when smoke continues arriving.

In Singapore, the western hourly PM2.5 concentration rose to 243µg/m3 at 2pm. The article says thundery showers possibly kept it from crossing into the very high band, defined there as above 251µg/m3. This is a concrete example of rain interrupting a rise in airborne pollution.

The benefit depends on where and how much rain falls, and on continuing winds. Forecast showers over Singapore and nearby areas may reduce haze. However, smoke haze from Sumatra may still drift in, while showers over Kalimantan could also help reduce smoke transport by affecting local conditions.

Winds move smoke from fire areas through the atmosphere. When air flows from Kalimantan or Sumatra towards Singapore, it can carry smoke across the sea and into Singapore. The article links the haze to fires in Kalimantan and says south-easterly winds helped the smoke drift towards Singapore.

The wind direction controls the route and amount of smoke transported. NEA expects winds tomorrow to shift from the south-southeast or south. That change could reduce smoke haze moving from Kalimantan to Singapore. Smoke haze from Sumatra, however, may still drift towards the island under the changing regional airflow.

In the first two days of the coming week, winds are expected to gradually weaken and blow from the southeast or south. NEA says this could further decrease Kalimantan smoke transport, although Sumatra haze may continue drifting towards Singapore. Showers are also forecast over Singapore and parts of Kalimantan.

PM2.5 refers to fine particles with a diameter of 2.5 micrometres or less. They are much smaller than visible dust and can remain suspended in air. Because they are light and tiny, moving air can carry them over long distances, including from fires in Kalimantan or Sumatra towards Singapore. The article reports PM2.5 readings by region and hour.

The western reading stayed in the elevated band for 18 hours, rose to 158µg/m3 at 11am, and reached 243µg/m3 at 2pm. These measurements show how concentrations can build as smoke arrives. Showers may wash some particles down, while changing winds can alter how much smoke reaches Singapore.

Fine particles matter because people can inhale them. Health authorities therefore use PM2.5 readings to guide decisions about outdoor activity. The article advises the public to check the latest concentration readings. Although fires continued elsewhere, weather conditions could temporarily reduce transport and airborne levels in Singapore.