Canada’s health care system could be a lot greener, experts say.

According to a new report, the health care system is the third-highest-emitting health system per capita in the world — behind Australia and the U.S. — but it represents not quite five per cent of Canada’s total greenhouse gas emissions.

By comparison, Canada’s agricultural sector accounts for about 10 per cent of emissions, the transportation industry 24 per cent and the oil and gas industry 27 per cent, according to government data.

Health care is relatively efficient, though, as it accounts for around 11 per cent of economic expenditure, but only five per cent of emissions, one study found.

But that doesn’t mean it can’t do better, the authors say.

“We all have a responsibility to do our fair share,” said Dr. Courtney Howard, an emergency room doctor in Yellowknife and lead author of the 2019 Countdown on Climate Change Briefing for Canadian Policymakers.

“It’s like a budget. Five per cent over time adds up,”

The report is part of the Lancet’s annual Countdown on Health and Climate Change Report, released Wednesday. This year’s report found that children around the world were at risk from climate change, including from malnutrition as a result of a changing food supply and infectious diseases that are expected to spread more easily.

Canada’s country report suggests that we cut back on emissions in the transportation sector, develop better plans to deal with wildfires, and clean up the health care system itself.

“One of the first things they taught me in med school was ‘do no harm,’” Howard said. “And so we want to be consistent with that in terms of how we’re actually conducting our own operation.”

Hospitals and acute care facilities are big contributors to emissions in health care, she said. Aside from basic things like keeping the lights on, what goes on in an operating room can also have a big impact.

A recent study comparing three operating rooms in Vancouver, Minnesota and the U.K. found that anesthetic gases used during surgery contributed significantly to a hospital’s carbon footprint.

So, too, did the ventilation systems in the operating room, which completely circulate the air many times a day. They constituted about 52 per cent of an inpatient hospital’s energy use.