Hazy conditions are back after a period of needed respite, as prevailing south-southeasterly winds have blown the haze from Sumatra into Singapore skies, pushing the Pollutant Standard Index (PSI) into the unhealthy range.
General view of the Singapore Central Business District area shrouded in haze. Photo: Reuters
With several upcoming runs on the calendar, runners are advised to take extra caution when exercising outdoors.
Dr Derek Li, who is also an elite marathoner, said exercising in the haze can be harmful to the lungs.
“There is a lot of very microscopic particulate matter in the air, and that actually gets into our lungs when we breathe in,” said the 33-year-old general practitioner.
“These pollutants can in theory interfere with our body's ability to extract oxygen from the air and into our bloodstream to be used. So when it's hazy, the amount of oxygen we can utilise from the air actually gets less, and that actually puts more strain on our lungs and our hearts.”
The doctor recommends people to keep a lookout for the PSI levels when deciding to exercise outdoors. This is especially so for people with health and breathing problems.
People swim in an infinity pool overlooking the skyline of the Central Business District shrouded by haze in Singapore. Photo: Reuters
“If you have any forms of allergies, whether it is skin allergies, nose sensitivities or asthma, then you need to be extra careful. Once the PSI goes above 100, then I would recommend doing your exercise indoors,” said the doctor who has a personal best of two hours 42 minutes in a marathon.
“For healthy people, you can probably handle anything up to 200 PSI in theory. But for strenuous exercise, the cut off will be about 100 PSI before you should do it indoors.”
While the N95 mask works just fine for light outdoor activities such as walking, it is not a foolproof solution for exercise.
“The breathing resistance is much higher when you wear a mask because of the filter system in the mask. You have to get used to that and realise that the breathing will be 50 per cent to even twice as hard for a particular effort level when you wear the mask,” he said.
“An N95 mask has to fit completely around your face for it to work. If the fit is off, or your face distorts during breathing when exercising, then there is potential for leakage of pollution into your breathing space. So an N95 mask is not a perfect solution for running in the haze.”
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