Singapore’s Ministry of Health is steering residents toward one-hour PM2.5 readings, not only the 24-hour PSI, when deciding whether to mask up or skip outdoor exercise during the longest unhealthy-air stretch since 2015.
Channel News Asia reported on 18 October that MOH’s latest haze advisory tells the public to use hourly PM2.5 bands for immediate activities. Vulnerable groups — including the elderly, pregnant women and people with chronic heart or lung disease — should avoid outdoor exertion when hourly PM2.5 enters the high band of 151 to 250.
That nuance matters because PSI is a rolling 24-hour average of six pollutants. Western Singapore saw a season-high 24-hour PSI of 230 on 18 October, while one-hour PM2.5 elsewhere ranged from normal in the north to elevated in central and eastern regions at 5 p.m.
Why clinics are busy
General practitioners across the island have reported more haze-related visits since early October. Symptoms are mostly upper respiratory — cough, throat irritation, wheeze in asthmatics — rather than acute pollution injury, but repeated exposure still warrants medication reviews for chronic patients.
Retailers have restocked N95 inventory after CASE urged shoppers not to hoard masks earlier in the week. Pharmacies said demand spikes track hourly PM2.5 pushes on the myENV app more than evening PSI headlines.
Practical thresholds
NEA forecast the 24-hour PSI between 100 and 190 on 19 October with rain possible. Rain can knock down particulates quickly, creating windows where hourly readings improve before the 24-hour PSI catches up. Health Ministry guidance is built for that lag: check the hour, then decide on the jog or the school PE lesson.
If you feel unwell after outdoor exposure, seek medical advice and reduce strenuous activity until air quality normalises. MOH has not issued a blanket school closure order; decisions remain with institutions watching both PSI and PM2.5.
Schools and sports
MOE has left most schools open while principals suspend outdoor assemblies when hourly readings spike. Parents should watch school notifications alongside myENV, especially for asthmatic children carrying reliever inhalers.
SportSG reopened ActiveSG outdoor sites on 17 October after earlier closures, but coaches are told to shorten drills when PM2.5 enters elevated bands. The health ministry’s mask advice applies to spectators as much as athletes.
Pharmacies report steady N95 sales without the panic buying seen in 2015, partly because retailers capped bulk purchases after CASE’s advisory.