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The Ontario government is proposing to add regulations to the province’s Occupational Health and Safety Act to limit “heat stress” and heat-related illnesses as climate change pushes global temperatures higher.

According to a proposal posted Tuesday, the Ministry of Labour, Immigration, Training and Skills Development is conducting a regulatory impact analysis of the amendments to identify and assess “potential benefits and costs.”

Ministry spokesperson Anuradha Dhar wrote in a statement to The Globe and Mail that “employers and supervisors have a duty to take every precaution reasonable in the circumstances for the protection of a worker, including protection in hot environments.”

The most significant proposal is the introduction of heat stress exposure limits based on guidelines from the American Conference of Governmental Industrial Hygienists.

However, some experts believe the proposals may not do enough to protect workers or truly take into account the nuanced ways heat affects people’s health.

Glen Kenny, a professor of physiology at the University of Ottawa and the lead investigator of Operation Heat Shield Canada, which looks at the impact of rising global temperatures in Canada, said the U.S. association’s guidelines are limited and provide insufficient protection for younger and older workers.

“We’re hanging our hat on a guideline that’s already flawed,” Prof. Kenny said. “The guidelines assume that everybody is the same. It’s not true.”

Prof. Kenny said the human body’s ability to dissipate heat decreases 5 per cent per decade as we age. Women are also less capable of dissipating heat than men, as are people with poorer overall physical health and pre-existing conditions such as diabetes.

What are the health risks of extreme heat?

The three most important factors that determine how everyone experiences heat stress, Prof. Kenny said, are the temperature of the environment, the clothing someone is wearing and the work effort – nuances that are not reflected in the U.S. guidelines.

He said the guidelines and technologies used by many companies are outdated – but he does applaud the government for attempting to address the issue.

“I have to give them credit for bringing awareness,” he said.

Still, the ministry just isn’t going far enough, he added. “I’m getting questions from people – they don’t understand how this is going to be applied. It hasn’t really changed much.”

Anna Gunz, an associate professor at the Schulich School of Medicine and Dentistry at Western University, said there are lots of obvious ways heat affects the human body, but the less obvious ways can have longer lasting and more dangerous outcomes and may not be accounted for in the ministry’s proposal.

“There are other diagnoses that people aren’t necessarily aware of. For example, in the heat waves there is an increased incidence of out-of-hospital cardiac arrest,” Dr. Gunz said.

Strokes, pneumonia and respiratory attacks can also be associated with heat stroke and other heat-related illnesses, Dr. Gunz said. She points out that the manifestation of these conditions can be delayed after heat exposure, particularly among workers in hot indoor environments such as factories, greenhouses and shipping containers.

“There’s lag times that we see. So it might not be attributed to their workplace, but it still might be associated with the stress that they were under,” Dr. Gunz said.

The lag times mean the conditions are often not accounted for in medical records and workplace policies, affecting insurance coverage and compensation for workers who may require time off.

Dr. Gunz said regulations must properly define working conditions and ensure accessibility to cooling measures so workers can take breaks and lower their body temperatures when working in hot environments.

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