Wildfire smoke is an increasingly important public health issue – one that requires further research to understand the long-term effects of exposure – said scientists who took part in a press briefing at the 2020 AAAS Annual Meeting in Seattle.
Researchers identified three issues driving the increasing threat wildfire smoke poses to public health in the United States. First, wildfires are growing in severity, especially in the American West, said Wayne Cascio, director of the Center for Public Health and Environmental Assessment at the U.S. Environmental Protection Agency.
Wildfires frequency is also increasing. “Fire season is turning into fire year," said Joseph Domitrovich, an exercise physiologist with the U.S. Forest Service.
There also has been a rise in the number of people who are moving into the "wildland-urban interface," which the Forest Service defines as the zone where “humans and their development meet or intermix with wildland fuel.” These spaces then become particularly susceptible to wildfire, though Cascio also noted that wildfire smoke can travel vast distances into urban areas.
Finally, an aging population means those most vulnerable to wildfire smoke is growing. Older adults are among those most in jeopardy, along with children as well as people with chronic illnesses like coronary artery disease or chronic obstructive pulmonary disease. Pregnant women are likely part of this group as well, said Cascio.
The long-term health effects are not known, a question that looms large as researchers investigate many dimensions of wildfire smoke health impacts. Domitrovich, for instance, is working on a multi-year study to look at overall health, including the effects of smoke, on wildland firefighters, who spend an average of 100 days per year fighting fires.
Panelist Lisa Miller, a professor of anatomy, physiology and cell biology at the University of California, Davis, is investigating the long-term health impacts of acute wildfire exposure on a group of rhesus monkeys exposed to smoke during a series of wildfires in 2008. She has followed this group of monkeys since infancy and shared new results at the briefing, having found evidence of immune dysregulation, changes in the lung function and smaller, stiffer lungs in these exposed animals.
Although Cascio noted that the risk to vulnerable humans is thought to be quite small, he offered several guidelines for avoiding exposure to wildfire smoke. Vulnerable groups should stay indoors when possible, particularly avoiding any physical activity outdoors, which increases respiratory rates and consequently increases exposure to smoke.
Cascio also recommended that anyone staying indoors to avoid smoke should be mindful not to generate indoor air pollution. Forgo the use of candles and incense and realize that cooking can create indoor air pollution as well, he advised.
Public health professionals are split on whether N95 respirators are helpful. While some public health departments advise their use, others have concerns that people don’t know how to use them properly or that they promote a sense of complacency among users, Cascio said.
During the Camp Fire – the 2019 wildfire that was the deadliest and most destructive in California’s history – Cascio saw a number of young people out jogging with N95 masks, which he advised against.
“People really don’t know that much about wildfire smoke and its potential health consequences,” Cascio said.