As some brave Canadians undertake polar bear dips on New Year's Day amid frigid weather, an expert in how humans adapt to extreme temperatures says the biggest concern won't be the day's mercury reading.
"It's probably more the organization of the polar bear plunge that is more important," said Stephen Cheung, a professor at Brock University in St. Catharines, Ont., who also serves as the Canada Research Chair in environmental ergonomics, which is the study of humans in extreme environments.
He said because most people will only be in the water for a minute or two, they aren't at risk of getting hypothermia.
Cheung said it's important for plunges to have first responders on site in case something goes awry, which is something the polar dip taking place in Herring Cove, N.S., will have.
Cheung previously taught at Dalhousie University and lived in Herring Cove, and praised how the Herring Cove Polar Bear Dip is run.
Having backup is key, which is why people taking the plunge on their own with nobody around is a bad idea.
"Those kinds of unsupervised polar bear swims can be a lot more hazardous because you have no backup if anything goes wrong," said Cheung.
How to prepare for the dip
For people waiting to take the plunge, Cheung said they should be wearing as much clothing as possible. After taking a dip, they'll want to towel off and get out of the clothes they were wearing in the water.
"When your clothes are wet, when your skin is wet, that's gonna suck away heat a lot faster," said Cheung.
On site, if there's a beach bonfire happening, that will do the trick. Alternatively, warming up indoors or hopping into a hot tub are also acceptable, said Cheung.
He said using a hot tub is fine because the individual wouldn't have hypothermia, so there wouldn't be any risks with the sudden temperature increase.
At the Digby Neck Polar Bear Dip, there will be a beach fire to start the warming-up process. Afterwards, participants will head to a home for a post-dip party where there will be a fire burning, and chili and chowder served up.
Monday's weather forecast
CBC meteorologist Kalin Mitchell said Monday's weather will certainly be putting the "polar" in polar bear dips.
Around the coast, temperatures are expected to be –10 C at sunrise, and with the wind chill it will feel like –17. By noon, the temperature should be closer to –7 C, –13 with the wind chill.
Robert MacLellan is one of the organizers of the Herring Cove Polar Bear Dip. He said the temperature isn't the big thing to worry about.
"Whether or not it's a sunny day or a slightly colder day, the difference in temperature isn't that acute," he said.
Dippers worried about wind
MacLellan said the wind is the biggest concern.
According to Mitchell, the winds will be steady from the northwest and be around 20 km/h through the morning, but should become lighter by noon.
"That's not bad," said MacLellan.
This is the 24th year for the Herring Cove Polar Bear Dip and he said they've done many plunges in colder temperatures.
How the human body responds to cold temperatures
So, what happens when people take the plunge?
"Your skin temperature drops very quickly and that sends a response to your brain and it triggers what's often called a cold-shock response.… The cold-shock response involves, really, a fight-or-flight response to an extreme, so you'd have a very high breathing rate, it will be very hard to control your breathing, so there's that hyperventilation response," said Cheung.
The body's heart rate will skyrocket, which is why polar bear dips aren't good ideas for people with heart problems.
Cheung said one of the reasons why polar dips can be risky are that if people are hyperventilating, they may not be able to hold their breath, which could lead them to ingest water and drown.
Booze is a bad idea
One thing people must not do is drink alcohol beforehand.
"That's the absolute biggest no-no," said Cheung.
Besides having poor motor control and not being as stable, alcohol will cause the body to lose heat faster.