AUSTRALIA – The choking haze blanketing Sydney is turning Australia’s biggest city into a veritable laboratory, offering the world better insight into the health effects of toxic air from wildfires.
Doctors are warning of a wave of lung and heart-related deaths as smoke from wildfires burning across the region envelops Sydney. There’s been a spike in emergency room visits and, longer term, the crisis may harm unborn babies and trigger an increase in cardiovascular disease, research suggests.
While cities from Beijing to New Delhi have demonstrated the risks of toxic air, studies have largely focused on the polluting effects of burning gasoline and coal. In contrast, the suffocating haze in Sydney has been caused by the combustion of at least 2.7 million hectares (6.7 million acres) of carbon-dense bushland over the past month.
“Australia is well-placed to do studies where it’s just wood smoke because we don’t have that additional fossil-fuel component,” said Ivan Hanigan, a data scientist at the University of Sydney who focuses on the health impacts of air pollution and extreme weather. “We’re heading into uncharted territory of just consistent, long-term exposure, which Sydney hasn’t had before.”
With wildfires a persistent and growing threat in other spots around the world, including California and Alaska, the research findings from Australia could give scientists an opportunity to gain critical insights. Sydney’s air quality is typically very good, so researchers should be able to identify how a single, very large hit of pollution can change an individual’s health trajectory.
Read More: Sydney Air Pollution Is So Bad It’s Setting Off Fire Alarms
More than 10% of the forests in New South Wales state’s national parks, including a fifth of the Blue Mountains world heritage area that flanks western Sydney, have been burned in the fires, the Guardian newspaper reported earlier this month, citing state government data. On Tuesday, as smoke shrouded the harbor bridge and opera house, Sydney recorded pollution levels 12 times higher than the threshold for “hazardous.”
Polluted air poisons 9 out of 10 people globally, and kills more than 7 million prematurely every year, according to the World Health Organization. Rapidly industrializing countries carry the heaviest burden because of the emissions from power plants, factories, automobiles, and biomass burning for land clearance.
The main cause of illness is exposure to small particulates of 2.5 micrometers or less in diameter, so-called PM2.5 matter, that can embed deep into the lungs and cause inflammation, heightening the risk of cardiovascular and respiratory disease, and cancers.
Read More: From London to Delhi, Dirty Air Is the ‘New Tobacco’
Besides the fine PM2.5 particulates, wildfire smoke contains hundreds of other components, and is more strongly associated with worsening asthma symptoms than matter from sources such as vehicle emissions.
“We know that wildfire fine-particulate matter differs from that produced, for example, from coal combustion,” said Joan Casey, an assistant professor of environmental health sciences at Columbia University’s Mailman School of Public Health in New York. “What’s more interesting is how these extreme air pollution episodes in regions with relatively little air pollution at baseline may lead to both short- and long-term health consequences.”
Casey, who lived in California during the state’s devastating 2018 wildfire season, said researchers may be able to follow pollution-exposed Sydneysiders over a number of years to gauge the effects on their health.
“This type of data can help health-care systems prepare and respond to such events more effectively,” Casey said in an email. “It can also inform policies we should put in place to protect public health.”
Donna Green, who researches human-environment interactions at the University of New South Wales, said she plans to install a “network of new air pollution monitors” to conduct detailed analysis of the effects across metropolitan Sydney focusing on particular groups, such as school-age children and outdoor workers.
Certain age groups may be more vulnerable to harm from wildfire smoke, according to the U.S. Environmental Protection Agency. Risk is generally higher during childhood, lower in young adulthood, and greater in middle age through old age as the incidence of heart and lung disease, hypertension, and diabetes increases. Pregnant women are also more vulnerable.
Hospital and ambulance call-out data for Dec. 5-11 show a surge in demand for emergency services for asthma and other breathing problems compared with the five-year average, said Richard Broome, director of environmental health with the New South Wales state health department. Emergency department presentations were 48% higher, while subsequent hospital admissions increased 28%, and ambulance calls jumped 41%.
“This is an unprecedented event for Sydney,” Broome said in a telephone interview.
Still, for most people, even “very high levels” of pollution rarely cause more than “relatively mild symptoms, like sore eyes, nose, throat, and a cough,” he said. Risks worsen for individuals with emphysema, angina and other pre-existing conditions.
Data needed to discern the immediate effects across Sydney’s 5.2 million residents may take months to collate and analyze, according to Green at the University of New South Wales.
“Although there can’t be much doubt there will be many excess deaths in this spring-summer season from the indirect impacts of the air pollution, the additional sickness and disease at the population level over coming years is likely to be the big unknown,” she said in an email.