Nearly two years after 619 people died due to extreme heat during the 2021 B.C. heat dome, a new study shows that people with schizophrenia and other mental health disorders were most at risk.
The BC Centre for Disease Control compared deaths recorded from June 25 to July 2, 2021, with the same eight-day period from 2012 to 2020 to learn how mortality rates among those with chronic diseases differed.
The highest mortality rate was in people with schizophrenia. During the 2021 heat dome, people with schizophrenia had a risk of dying that was three times higher than the average mortality rate experienced by that demographic in previous years.
Sarah Henderson, the centre’s scientific director of environmental health services co-authored the study.
“Schizophrenia really stood head and shoulders above” the other comorbidities her team studied, she said.
“Public health messaging about extreme heat [has] specific callouts for individuals with cardiovascular disease, with respiratory disease or with diabetes. We expect all of those things to be risk factors, but you don't necessarily [see] a call out for people with schizophrenia or severe mental illness,” she added.
Henderson’s team noted the many aggravating factors those with schizophrenia could have been faced with during the heat dome.
These factors include social isolation and economic marginalization, as well as an inability to perceive the threat of heat. Of the 309 people with schizophrenia who died in the heat dome, 47 per cent reportedly also used illicit substances, which could have increased their vulnerability to extreme heat.
Antipsychotic medications prescribed to treat schizophrenia can negatively affect the body’s ability to regulate heat, though Henderson cautions that people prescribed antipsychotics should not stop taking their medication during periods of extreme heat.
Instead, she says, the public health focus should be on “checking in with people if we know a heat event is coming and help them find ways to stay cool during that event.”
In addition to revealing striking data about schizophrenia, Henderson’s team also learned how other chronic diseases could impact mortality during extreme heat.
Those with depression were slightly more likely to die during the extreme heat event.
People with substance use disorder, asthma, chronic kidney disease and diabetes also experienced higher mortality rates. Having three or more chronic diseases was also associated with increased odds of death during the extreme heat event.
Surprisingly, people with other diseases like angina, dementia and heart attacks were at decreased risk of mortality during the heat dome. Researchers theorized that this could have been because these individuals were known to be at risk from the heat event and received heightened care, such as more health checks and access to air conditioning.
Researchers also found there was a 95-per-cent increase in daily mortality overall during the extreme heat emergency.
Overlapping mental health and poverty play a role in mortality
Rowan Burdge, the provincial director of the BC Poverty Reduction Coalition, says the groups her organization serves were not only extremely impacted by the heat dome, but were unable to advocate for themselves at the provincial level.
The coalition primarily serves low-income populations as well as intersecting demographics like Black, Indigenous and other racialized people, seniors, people with disabilities and people who use drugs.
Burdge, who represented the BC Poverty Reduction Coalition on the province’s extreme heat death review panel, said risk factors like mental health, disability, drug use and poverty often go hand in hand.
“I’ve worked with many people experiencing poverty who are living in terrible material conditions… bugs and mould in their apartment or not being able to have adequate food… those things deeply impact people’s mental health for the worse,” they say.
The extreme heat death review panel report, released last year, revealed 39 per cent of heat dome deaths occurred in multi-unit buildings, while social or supportive housing and senior or long-term care homes accounted for 10 and seven per cent of deaths, respectively.
The report also made recommendations about cooling, including incentivizing building retrofits that encourage active and passive cooling and requiring new developments to meet certain cooling criteria. However, these changes won’t likely benefit those living in existing multi-unit low-income housing anytime soon, Burdge says.
“There are thousands of people living in BC Housing buildings that were made before any new adjustments to the building code — we need to be retrofitting those spaces,” Burdge said.
In addition to working with vulnerable people who were most impacted by the heat dome, Burdge has seen the affect of extreme heat on chronic disease firsthand because she has Type 1 diabetes and lives in a multi-unit apartment building that does not have air conditioning.
People with diabetes can experience increased difficulty regulating their body temperature and staying hydrated. In addition to the physiological effects of hot weather, extreme heat can also damage diabetes medicine and equipment.
“Because my sugars were high, I had headaches, dizziness, confusion — I didn’t actually have the cognitive wherewithal to realize how bad the impact was,” Burdge said.
The BCCDC study found the mortality rate among people with diabetes who died due to heat-related causes was 1.10 times higher during the extreme heat event than during the same period in previous years.
“It wasn’t until the heat had passed that I started to regain cognition and realize how the impacts had been so severe,” Burdge said.
The BCCDC is still working to get a full understanding of how the 2021 extreme heat event impacted British Columbia’s most vulnerable residents — not just those who died.
“We’ve still only focused on mortality during the event,” Henderson says. “We haven't looked at all of the people who visited the ERs and all of the people who called 911. There's this much broader health impact of the event that my group hasn't even touched yet.”
Two projects are also taking a closer look at those with schizophrenia who died during the heat dome as well as the broader risk factors for people with schizophrenia during periods with warmer temperatures.
Future-proofing in the hot seat
Environmental experts are tentatively predicting another hot summer in B.C., especially as climate change increases overall temperatures.
The extreme heat death review panel report included several recommendations for short- and long-term extreme heat mitigation strategies. The first recommendation was to introduce a co-ordinated provincial heat alert response system, which the province has begun fulfilling through its BC Provincil Heat Alert and Response System.
Other recommendations included identifying and supporting vulnerable populations at risk of dying during extreme heat emergencies, with the expectation that the Health Ministry would review the potential of issuing cooling devices like fans and air conditioning units to at-risk residents during extreme heat events.
The results of that review should have been released by Dec. 1. But the Health Ministry still hasn’t released its findings, telling a CBC reporter earlier this month the ministry needed more time to ensure “a thorough analysis and appropriate engagement is done before finalizing the report.”
Burdge says the delay is disappointing as the province heads into its second summer since the heat dome.
“For people who are low income or experiencing poverty, there really hasn't been enough put into place to change any of these outcomes,” they said.
“If we had another heat dome this summer, I don't think there would be a major reduction in the kind of death and suffering that we saw from 2021.”