Wildfire smoke may be more dangerous than equivalent levels of pollution from traffic, industry and other sources, raising the risk of hospitalization for heart and lung disease and worsening survival odds for lung cancer patients, according to two large-scale studies from the Icahn School of Medicine at Mount Sinai.
For the studies, published in The Lancet Oncology and Nature Communications, researchers examined the long-term health effects of wildfire-related fine particulate matter, known as PM2.5, compared with PM2.5 from non-wildfire sources.
In the lung cancer study, the team analyzed data from 414,016 adults aged 65 and older in the SEER-Medicare database, estimating each patient's wildfire and non-wildfire PM2.5 exposure based on where they lived. Both types of pollution were linked to increased mortality after a lung cancer diagnosis, but wildfire-related PM2.5 proved substantially more toxic per unit of exposure. Although it accounts for only about 4 percent of total PM2.5 nationally, it was responsible for roughly 17 percent of the mortality tied to overall PM2.5 exposure. Higher numbers of smoky days and longer smoke exposure were also linked to worse survival.
In the second study, researchers analyzed hospitalization records from 20 U.S. states between 2006 and 2019, covering more than 57 million cardiovascular hospitalizations and nearly 33 million pulmonary disease hospitalizations. Long-term exposure to wildfire-related PM2.5 was tied to higher hospitalization risk for conditions including heart failure, ischemic heart disease, hypertension, asthma, pneumonia and chronic obstructive pulmonary disease. The researchers also noted stronger associations found among racial and ethnic minority populations, city residents and communities with lower educational attainment and higher socioeconomic deprivation.
The researchers say the findings suggest wildfire smoke should be treated as a distinct environmental health threat requiring its own mitigation strategies, rather than being folded into broader air quality policy.
“As wildfire activity continues to grow around the world, understanding the health consequences of wildfire smoke has become increasingly urgent,” said senior author Yaguang Wei. “These studies represent an important step toward identifying who is most vulnerable and what strategies may help protect public health in a changing climate.”
Future work will focus on identifying which chemical components of wildfire smoke drive its heightened toxicity and the biological mechanisms behind its effects on the heart, lungs and cancer outcomes.
Data from The Mount Sinai Hospital/Mount Sinai School of Medicine