Long-term exposure to bushfire smoke may increase the risk of hospitalisation for heart disease in older people, according to a study that adds to growing evidence of the health costs of a warming planet.
Researchers analysed hospital records from more than 65 million Americans aged 65 and over, examining rates of cardiovascular disease alongside neighbourhood exposure to fine particle pollution from wildfire smoke over several years.
They found that people living in areas with higher average smoke exposure over a three-year period were more likely to be admitted to hospital for heart conditions.
The study, published in the Journal of the American College of Cardiology, reported increased risks for overall cardiovascular disease, ischemic heart disease – caused by narrowed arteries reducing blood flow to the heart – and arrhythmias, which are irregular heart rhythms. The association was strongest at moderate levels of smoke exposure and among people from lower socioeconomic backgrounds.
PM2.5 refers to tiny airborne particles measuring 2.5 micrometers or smaller, which can penetrate deep into the lungs and enter the bloodstream. Short-term exposure to such pollution has already been linked to heart attacks and strokes. This study suggests the cumulative effects over several years may also be significant.
In places like Australia, extreme bushfire seasons have become more frequent and intense in recent years. The 2019–20 “Black Summer” fires burned more than 24 million hectares, shrouding cities including Sydney, Melbourne, and Canberra in hazardous smoke for weeks. Research has previously linked that smoke to spikes in respiratory and cardiovascular hospital admissions.
Climate scientists have found that rising temperatures and prolonged drought conditions are increasing the likelihood of severe fire weather in parts of Australia. As fires become larger and burn for longer, smoke can travel thousands of kilometres, exposing millions of people far beyond the fire front.
The researchers said that as climate change intensifies the frequency and scale of wildfires, public health strategies will be needed to reduce exposure and protect vulnerable groups.
Earlier, Australian researchers warned that bushfire smoke may be increasing the risk of mental health crises among children, researchers warned in a new study.
Hospital visits linked to children’s mental health rose in the six days after exposure to pollution from bushfires, with the effect stronger than that seen following exposure to air pollution from other sources. The research examined levels of particulate air pollution following bushfires and compared them with pollution from non-fire sources such as traffic and industrial activity.
It found that bushfire-related pollution was linked to a higher number of emergency department visits for mental health conditions by children and adolescents than other types of air pollution at similar concentrations.
