Photo: archive photo
The Bennett Bridge was suffocated by smoke from a forest fire in August 2019
Exposure to air pollution in Canada is causing nearly 8,000 deaths a year, according to a new study.
The research, published today in a report by the Health Effects Institute (HEI), looked at the mortality of 7.1 million Canadians over the past 25 years.
Long-term exposure to particles (PM2.5) was found to be most harmful when combined with other pollutants such as ozone. As of 2016, it caused 7,848 deaths a year, although it’s probably a lower estimate compared to what Canada is experiencing now.
But it was found that even low concentrations of PM2.5, a pollutant released into the air by forest fires, wood stoves and fossil fuel emissions from cars and trucks, help increase the risk of death in people who already they suffer from cardiovascular and heart diseases. , diabetes, pneumonia or a respiratory illness such as COPD.
“There really isn’t a safe level of air pollution,” said the study’s lead author, Michael Brauer, a professor in the School of Population and Public Health at the University of British Columbia.
Brauer and colleagues combined satellite data, local air samples, and atmospheric modeling to measure PM2.5 concentrations across Canada from 1981 to 2016.
After analyzing the data, the researchers found that cities had particle concentrations nearly three to eight times higher than rural areas. Until 1990, the highest concentrations of PM2.5 were found in large cities, such as Vancouver, Toronto, Hamilton, and Quebec City.
And while these levels of pollutants declined in the following years, it was found that even low levels increased the risk of premature death.
“We harvested the low fruit”
Brauer’s data temper the results of a study published last year, in which Health Canada estimated that all forms of air pollution contribute to the early deaths of 15,300 Canadians each year.
In this study, the BC interior suffers from some of the biggest consequences of air pollution in the country.
Between 2013 and 2018, the 10 census divisions in the country with the most exposure to PM2.5 were all inside BC, according to a 2021 Health Canada analysis of the impacts of air pollution on the world. human health.
Of these, half of the census divisions, including Central Kootenay, where Nelson is located, were among the top 10 parts of the country with the highest per capita rates of premature death.
Brauer said climate change, from rising temperatures in cities to devastating forest fires, threatens much of the progress that has been made in recent decades.
“We picked the low fruit,” he said. “With a warmer climate, things probably won’t get better without more aggressive action … And the faster we decarbonise. we will eliminate these health impacts faster. “
The growing impact of bad forest fire seasons has led some medical professionals to rethink the way they diagnose health crises. After a record heat wave and a brutal fire season, a BC doctor even diagnosed a patient as suffering from “climate change.”
“A lot of people at the Kootenays thought this would be a good place to hide while the rest of the world collapses. But of course it’s hitting us here, just like in many places, and we’re really seeing the impacts,” he said. said Dr. Kyle Merritt, head of Nelson’s Kootenay Lake Hospital.
The overall number of deaths from air pollution is likely to be much higher
Worldwide each year, the World Health Organization (WHO) estimates that outdoor air pollution causes about 4.2 million deaths. Brauer’s research would increase this estimate by a further 1.5 million.
However, few jurisdictions have air quality standards that reflect the risk Brauer encountered in his study. Canada’s 2012 ambient air quality standards set a path to reducing air pollutants in a gradual approach by 2025. Current standards recommend PM2.5 concentrations below 8.8 micrograms per meter square.
In the US, national standards stand at 12 micrograms per square meter.
Meanwhile, recently updated WHO standards reduce this threshold to 5 micrograms per square meter.
But none of these pollution limits meet the 2.5 micrograms per square meter limit, beyond which Brauer says it increases the risk of mortality.
This should be a signal to regulators both in Canada and around the world that air quality standards need to be strengthened, Brauer said.
“Globally, it means we have to keep up with that,” he said. “This will be there, even relatively clean countries, Western Europe, North America … there is still a significant impact.”
Photo: contributed
PM2.5 concentrations decreased during the study period, but even low exposure levels significantly affected the risk of premature death. Brauer et al. (2022)
The UBC-led study is the latest in a series of HEI-supported studies that study how even low levels of outdoor air pollution affect human health.
The first, a 2021 study that looked at the effects of particulate matter, carbon black, nitrogen dioxide and ozone in 11 European countries, found “significant” links between those exposed to low levels of pollution and mortality. early in people with cardiovascular and respiratory diseases. and lung cancer.
The second report, published earlier this year and focused on the United States, tracked the low levels of exposure to air pollution in 68.5 million large Americans. Once again, history repeated itself: even low levels of particulate exposure increase the risk of death.