Living near volcanoes exposes people to subtle lung damage due to volcanic air pollution.
Between fiery destruction, mudslides, and ash clouds that blot out the sun, volcanoes aren't short on spectacular threats to human life.
But on the island of Hawaii, residents living downwind of the actively erupting Kilauea volcano are at risk of a range of more subtle health problems, including bronchitis, asthma attacks, lung infections, and sore throats thanks to volcanic air pollution, according to a new study.
Kilauea has been erupting since 1983, oozing streams of lava in a relatively peaceful volcanic display. Gas from the eruption is rich in sulfur dioxide (SO2), though, and trade winds regularly waft it toward small communities on the southern part of the island.
Along the way some of the gas can morph into hazy sulfate (SO4) particles. Together they make up Hawaii's much-maligned volcanic smog, which locals have dubbed "vog."
Bernadette Longo of the University of Nevada-Reno and colleagues wanted to know how the pollution affects people who live with it every day. The team compared medical records from residents in the Kau district southwest of Kilauea to those living in areas where exposure to vog was rare.
Between 2004 and 2009, they found that high exposure to vog nearly doubled the risk of coming down with a sore throat or asthma attack, and elevated bronchitis risk in adults by 57 percent.
Children proved far more susceptible to vog-related diseases, with risk of upper respiratory infections nearly doubling. The likelihood of an asthma attack rose by a factor of five, and bronchitis risk was six times higher.
Kilauea's vog often swirls around the island to the west, wrapping the much more populous Kona coast in a noxious pall. When the winds shift, the cities of Hilo and Honolulu can suffer the same fate.
But the sparsely populated Kau area is by far the most affected. The local hospital, high school and elementary school have all begun real-time air quality monitoring to stay on the lookout for vog outbreaks.
"The schools installed air conditioners in every room; we found that they reduced particle counts indoors," Longo said. "It's a way of focusing on the 'how do you deal with this?' aspect of the problem."
Longo presented the team's findings last week at the annual meeting of the Geological Soceity of America in Portland.
While the team's work represents an important advance, Jon-Pierre Michaud of the University of Hawaii at Hilo said some important questions remain unanswered. Their analysis couldn't distinguish whether a case of acute asthma was brought on by vog or pollen, for example.
Also, the study only measured risks of acute diseases; it is unclear whether people who grow up with high vog exposure are more likely to develop chronic respiratory problems or other diseases later in life.
"I'd say a lot more isn't known about the physiological response to vog than is known," Michaud said.