SEATTLE – When Mount St. Helen erupted in 1980, it created a living laboratory for scientists – notably specialists in volcanoes, affected forests, river systems, wildlife – and human health.
But health experts “looked in the wrong place. We basically missed the boat,” Dr. Dorsett Smith said Wednesday during a discussion of volcano health effects at the 70th annual international scientific assembly of the American College of Chest Physicians in Seattle.
Smith is a clinical professor at the University of Washington and an expert on acute inhalation injuries.
Health experts reasoned that the greatest impact from the eruption’s 12-mile-high column of smoke and ash would be in areas closest to the mountain to the east, where winds carried visible ash deposits.
But the nearby deposits involved larger, heavier materials – not the finer particles that could cause breathing problems. Scientists were surprised at the minimal health impacts – but they might have found more if they’d focused the effort farther away, Smith said.
“We didn’t know much about air pollution at the time,” he said.
Concentrations and particle size vary because of wind conditions and distance.
“The higher the cloud and the larger the volume of ash, the longer it lasts and the farther it goes,” Smith said. “It’s that simple.”
Still, researchers here and elsewhere have found that healthy people and other mammals bounce back quickly from ash-related breathing problems.
In Washington state, the effects of the May 18, 1980, eruption were “rather minimal considering the huge amount of ash,” Smith said. A four-year study of 712 loggers found coughing and phlegm problems declined over the first year and were gone by the end of the study.
“It’s very similar to what we see following 9-11,” he said, noting the terrorist attacks on the World Trade Center left a lingering dust cloud over New York City for weeks.
Over time, rain settled the dust, acids degenerated, sharp-edged particles were smoothed out – and people at risk stayed indoors.
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