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Who’s most at risk during extreme heat?

People with mental illnesses like schizophrenia died at greater rates during the 2021 heat dome, a new study shows.
Paramedics attend an emergency call in Vancouver’s West End during the June 2021 heat wave. Recent research shows that people with schizophrenia had a heightened risk of dying during this heat dome.

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.”