Wildfires Are Getting Closer to Cities, and That Means More Heart Attacks

A new study shows that as the frequency of fires increases around the world because of climate change, more people are suffering from air pollution.
A pall of smoke hanging over the city of Sydney caused by bushfires burning out of control in the Blue Mountains in October 2013. (Photo: Phil Hillyard/Newspix via Getty Images)
Jul 16, 2015· 1 MIN READ
Katharine Gammon has written for Nature, Wired, Discover, and Popular Science. A new mom, she lives in Santa Monica.

With 35 wildfires currently burning along the West Coast of the United States, a new study shows how dangerous fires can be—for human hearts.

Researchers in Australia looked at the relationship between wildfire-caused air pollution and heart health. They examined rates of cardiac arrest and hospital admissions in December 2006 and January 2007. During these two months, smoke from fast-moving wildfires (which are called bushfires in Australia) reached cities far from the blazes.

The fires were some of the worst Australia has ever seen: The state of Victoria experienced the longest continuously burning bushfire complex in the country’s history, with fires burning more than 2.5 million acres over the course of 69 days.

“During the bushfires, the level of exposure is completely different from what we are exposed to every day,” said Anjali Haikerwal, doctoral candidate at the School of Public Health and Preventive Medicine at Monash University in Melbourne and coauthor of the study, which was published in the Journal of the American Heart Association. “The levels were so high, they exceeded all the standards around the world by four or five times.”

Haikerwal and her colleagues used sophisticated models showing the level of smoke exposure around the state alongside data from hospital admissions to find out what happened during the conflagration. They uncovered a 6.9 percent increase in out-of-hospital cardiac arrests, a 2 percent increase in emergency visits for coronary artery disease, and a nearly 2 percent increase in hospitalizations. The strongest effects were seen in older people and in men.

RELATED: Another Reason to Stop Wildfires: They’re Heating the Planet Faster Than Ever

Past research has shown that tiny particles, just 2.5 micrometers or smaller, can lodge themselves deep in the bloodstream and have a significant impact on the lungs, the cardiovascular system, and even the brain. But this was the first time researchers had looked at smoke specifically coming from fires rather than from cars, ports, or other sources of pollution.

So, Why Should You Care? As fires burn closer to cities and for longer periods of time, they increasingly affect human health. New research has found that as global temperatures have risen, the length of wildfire season has grown nearly 19 percent around the world.

Haikerwal pointed out that although the study showed larger effects for older people and men, no one really knows why. “It might be a difference in hormones or exposure to more outdoor pollution,” she said.

On average, 87 percent of particulate pollution from wildfires comes in the form of dangerous 2.5-micrometer particles. A 2005 study estimated that automotive and truck exhaust is the single most serious preventable cause of heart attack and is linked to 7.4 percent of all attacks.