Wildfire smoke exposure poses significant cardiovascular and respiratory health risks that persist for months after fires are extinguished, according to two new studies that analyzed millions of hospitalizations and health records across multiple states.
Extended Health Impact Duration
Research published in the journal Epidemiology found that particle pollution from wildfires continues to increase hospitalization risk for up to three months after smoke exposure. The study analyzed hospitalization records for residents of 15 states between 2006 and 2016, encompassing more than 13.7 million hospitalizations for heart diseases and nearly 8 million for respiratory conditions.
"Even brief exposures from smaller fires that last only a few days can lead to long-lasting health effects," said lead researcher Yaguang Wei, an assistant professor of environmental medicine at the Icahn School of Medicine at Mount Sinai in New York City.
The research demonstrated that risk increases proportionally with the amount of smoke pollution exposure, affecting residents across Arizona, Colorado, Delaware, Georgia, Iowa, Kentucky, Michigan, Minnesota, North Carolina, New Jersey, New York, Oregon, Rhode Island, Washington and Wisconsin.
Cardiovascular Conditions Most Affected
High blood pressure emerged as the health condition most significantly impacted by wildfire smoke exposure. Other conditions showing increased hospitalization rates included heart disease, stroke, irregular heart rhythms, pneumonia, COPD and asthma.
A separate study published in the Journal of the American Heart Association examined health data from more than 3.2 million adults enrolled in the Kaiser Permanente Northern California health system, focusing on two major 2018 California wildfires with dramatically different health outcomes.
Fire Duration and Exposure Patterns Matter
The California study revealed striking differences in cardiovascular risk between wildfires of varying duration and management approaches. People exposed to high levels of fine particulate matter from the Mendocino Complex fires in July and August 2018 had 23% higher odds of cardiovascular events that year, including heart-related death and hospitalization for heart attack, heart failure or stroke.
Those with high exposure from the Mendocino Complex fires showed nearly 36% higher odds for heart death specifically during 2018. However, survivors who breathed polluted air from the Camp fire showed no increased risk for either heart-related health crises or death.
"The Mendocino Complex and other fires were actively burning for almost 2 months, with smoke in the air for 26 to 51 days depending on the county," noted research scientist Stacey Alexeeff from the Kaiser Permanente Northern California Division of Research. "The Camp fire was contained more quickly, with smoke in the air for 11 to 15 days depending on the county."
Public Health Interventions Show Promise
The Camp fire study highlighted the potential effectiveness of coordinated public health responses. During that blaze, many schools were closed, outdoor events were canceled, and health officials urged residents to stay indoors or wear N95 masks when they could not avoid leaving their homes.
The types of materials that burned and resultant toxins may have also differed between the fires, contributing to varying long-term health risks.
Call for Improved Wildfire Management
Researchers emphasized that current wildfire prevention strategies require significant updates to address public health concerns effectively.
"Wildfires can burn for weeks to a month, and smoke (particle pollution) may linger in the air for extended periods, which may keep the air toxic even after a wildfire has ended," Wei explained. "Current wildfire strategies are outdated and ineffective. For example, prescribed fires can reduce wildfire risk but are mainly used to protect property rather than public health."
The research teams concluded that greater effort should be placed on wildfire management rather than relying solely on traditional air quality control strategies, particularly as climate change continues to increase wildfire activity.
"With ongoing climate change, large wildfires are a pressing public health concern and future work is needed to understand differences by wildfire," Alexeeff's team noted, calling for formal examination of how public health and individual protective actions may affect exposures and health outcomes during wildfires.
