California wildfire study's unexpected finding: Heart risk may surpass respiratory issues
Posted April 10, 2018 7:08 p.m. EDT
SAN FRANCISCO -- Last year's busy wildfire season was an all-too-close reminder that smoky skies can cause coughing, wheezing and difficulty breathing. As it turns out, though, the health issues don't end there.
One of the most comprehensive studies yet on the impacts of wildfire smoke in California, published Wednesday in the Journal of the American Heart Association, suggests that heart problems are as much a concern as respiratory problems, perhaps even more so.
The finding of elevated cardiovascular risk, as much as 40 percent higher when dense smoke is present, provides not only one more reason to steer clear of ash-filled air but another thing for health-care providers to consider when responding to wildfires.
During last year's deadly Wine Country blazes, millions were exposed to bad air while hospitals saw big upticks in people with complaints about smoke, sometimes hundreds of miles away. The new study focused on fires before last year, but its conclusions are equally pertinent.
``As we're having more and more wildfire events and smoke affects more and more people, communicating the real risks is important,'' said Zachery Wettstein, the lead author of the new report and a graduating medical student at UC San Francisco. ``Respiratory problems are serious but they may not be as deadly. Heart attacks and strokes can be very deadly.''
Wettstein's study found that exposure to wildfire smoke correlates with more hospital visits for coronary heart disease, irregular heart rhythm, heart failure, pulmonary embolism and stroke.
While cardiovascular problems have previously been linked to the components of smoke, which include toxic gases and menacing tiny particulates, research on the connection has been limited. Studying smoke impacts is not easy because of the unpredictable nature of fires. Fires make controlled settings and study groups hard to come by.
Wettstein and his fellow researchers at UC San Francisco, the California Department of Public Health and the U.S. Environmental Protection Agency drew their conclusions by analyzing more than 1 million emergency room visits during Northern and Central California's 2015 wildfire season.
They collected records from hospitals during a period of severe burns that included Lake County's Valley Fire, which destroyed nearly 2,000 homes, businesses and outbuildings. The researchers compared the hospital data with satellite observations showing where the smoke was thickest.
The group found that the risk of being treated for heart problems during a fire was higher than usual for men and women of all ages and greatest within a day of excessive smoke.
The elderly faced the most risk. Those 65 and older visited the emergency room up to 42 percent more often than usual for a heart attack and up to 22 percent more often for coronary heart disease.
``We're reaching the point at which a large population of baby boomers will be in an age group at higher risk for cardiovascular disease and stroke, so we'll have a greater population of susceptible individuals to these adverse health events,'' Wettstein said.
Respiratory problems, as expected, were also up among all age groups.
The study did not look at how such personal factors as medical history might affect a person's chance of suffering smoke-related harm. But the authors advised those with high blood pressure, diabetes and heart disease to be particularly mindful around smoke.
Wayne Cascio, a co-author of the study and acting director for the EPA's National Health and Environmental Effects Research Laboratory, said that better medical guidance and care is likely to result as the link between wildfires and heart problems is better understood.
``The findings have public health and clinical implications,'' he said in a statement. ``I think it will have a significant impact on how clinicians and public health officials view future wildfire events and the smoke that's generated from them.''
More people are likely to be exposed to smoke as wildfires become bigger and hotter in an age of climate change. The number of acres burned in the United States last year was second highest since the 1950s, following only 2015.
Public health officials generally recommend that people avoid smoky air by staying indoors and wearing filtering respirators, not dust masks.
The Wine Country fires in October, which killed 41 people and destroyed more than 6,000 structures, prompted more than a week of public health alerts across the Bay Area. Schools were shut down, nearby residents were urged to shelter in place and residents, even far from the flames, were advised to avoid vigorous activity outdoors.