As waves of smoke continue to spread across Sydney's skies, many have questioned the safety of exercising outdoors.
Steve Grant, owner of Rushcutters Health gym in Sydney's east, has witnessed more people signing up in December, to avoid exercising in the hazardous air conditions outside, when they would normally wait until January.
We shouldn’t avoid exercise, but we should choose when and where we do it carefully, experts advise.Credit:Getty
“It’s definitely more challenging to get people into the [outdoor] group classes at the moment, and a lot easier to get them indoors in the airconditioning without the smoke haze,” he says.
In fact, for the first time in the 10 years the gym has been operating, they have started moving some of their outdoor classes inside.
“Those bad days have been impossible outside,” Grant says. “You actually get sore eyes, exercising in the morning if it’s smokey. We’re just doing it based on how we feel and we’re like ‘you know what, it’s just not on today’.”
Dr Arnagretta Hunter, cardiologist and member of Doctors for the Environment, says there is “uncertainty” about what exercise is and is not safe in the current conditions.
“The magnitude of this event is unprecedented,” Hunter says. “Certainly in Australia we’ve never had an air-pollution event like this.”
To put it in perspective, Hunter refers to the 2019 MJA–Lancet Countdown report on health and climate change published in November, which found that less than 300,000 Australians were exposed to air pollution from bushfires each year during the four-year periods (2001 to 2004 and 2015 to 2018).
This year, however, it is "easily 10 million people” across NSW, Queensland and the ACT.
“That number is orders of magnitude bigger than it’s ever been in Australia so we don’t have any data or Australian experience to give us adequate guidance,” Hunter explains.
“The more exposure you get, the more likely you are to have problems, either acutely or down the track, so avoiding really hazardous periods outside is a good idea."
Those with lung and heart conditions as well as pregnant women and young children are particularly at risk of becoming “unwell quite quickly”.
"For most of us, ideally it won’t have longer-term health consequences but for the vulnerable population it could be quite profound.”
Hunter says people should not stop exercising ("there is a health advantage to maintaining some sort of exercise routine … because we are looking at probably months like this") but unless your gym has positive pressure ventilation — tightly sealed with a top-line air filtration system — moving indoors may not make a significant difference.
“There’s an assumption that inside air quality is better than outside,” she says. “But when you’ve got days at a time where air pollution is this hazardous, then inside and outside, the air quality is probably about the same.”
The type of exercise and its intensity may also not make a difference.
“A lot of the people I talk to have been wondering whether cycling, which is generally less intense than running, might be a safer undertaking but it’s really unclear,” Hunter admits. “I guess the analogy is with cigarette smoking and how deeply you inhale. I don’t know if it’s ever been proven that there are big differences in the risk. I think it’s dangerous regardless. But very anecdotally a lot of runners I’ve spoken to have found it more difficult to run where air pollution is high.”
The best strategy is to exercise when air pollution is not hazardous, avoiding times when the PM (particulate matter) is 2.5 or the air quality index is over 200.
“We have to be significantly more flexible with our exercise routines than a lot of us usually are," Hunter says.
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