Just a few weeks of exposure to the smoke from an intense fire has years-long respiratory and cardiovascular impacts, according to new research that sheds light on the possible long-term effects of bushfires.
Researchers studying the aftermath of the 2014 Hazelwood coalmine fire have linked exposure to fine particulate matter (PM2.5) in smoke to an increased risk over the following five years of needing to visit an emergency department for respiratory problems.
PM2.5 are tiny particles with a diameter of 2.5 micrometres or fewer, which are breathed into the lungs and can enter the bloodstream.
An increase in PM2.5 of 10 micrograms a cubic metre was associated with a 10% increase in respiratory presentations over half a decade, the study found.
Among people who had been exposed, the risk of emergency presentations for cardiovascular diseases including ischaemic heart disease was elevated for two and a half years after the fire.
The findings add to the emerging but limited evidence to date on the long-term health impacts of PM2.5 exposure from fires. Wildfire smoke and mine fire smoke “have a similar spectrum of toxic components”, the study’s authors wrote.
The Hazelwood coalmine was ignited by a bushfire in 2014 and burned for 45 days, resulting in plumes of smoke and ash over the Latrobe Valley in Victoria. Previous analysis has shown that 24-hour PM2.5 levels exceeded the Australian air quality standard of 25 micrograms a cubic metre in parts of the town of Morwell on 23 of those days, sometimes reaching levels 19 times the limit.
The research, published in the journal Environmental Research, compared the hospital records of 2,725 Latrobe Valley residents from 2009 to 2019 against data about their smoke exposure during the mine fire.
The study’s corresponding author, Yuming Guo, a professor of global environmental health and biostatistics at Monash University, said: “[With] just six weeks’ exposure to the coalmine fire smoke, there were long-term effects for human health.”
The Hazelwood research showed that the particulate matter in coalmine smoke was of higher health risk than other sources of PM2.5, he said.
“Because both coalmine fire and wildfire smoke have a higher concentration than background PM2.5, the issues … are very serious for the general population and also for vulnerable people [such as pregnant women, elderly people, or those with pre-existing health conditions].”
Guo said governments and communities would need to do more to prepare for future fires, given that amid the climate emergency bushfires are beginning earlier and the intensity of fire weather is increasing.
“People are sensitive to coalmine fire smoke and bushfire smoke – they need to find a way to protect people from exposure,” he said. “The [season] will be longer and the frequency will be much more than before.”
Much of the previous research into the effects of the coalmine fire, as part of the Hazelwood health study, focused on short-term impacts, with findings such as an increase in cardiovascular-related deaths in the six months after the blaze.
The researchers noted it was possible that the increase in emergency presentations over the five years “could have been mediated by changes in the socioeconomic environment in the area post mine fire, which could also have introduced a negative impact on health and wellbeing”.
The president of the community group Voices of the Valley, which was formed after the fire, Wendy Farmer, said the blaze had affected many more people than were tracked in the study.
The research focused primarily on residents of Morwell, a town that was badly affected. Farmer, whose husband worked in the Hazelwood mine before it closed in 2017, said: “Many of the workers and the emergency services of course did not reside in Morwell.
“I think there is a high percentage of the community that are still suffering from respiratory and heart disease that aren’t covered in this study.”
