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Wednesday, December 01, 2004 - Page updated at 09:32 A.M.

Mount St. Helens the state's No. 1 air polluter

By Sandi Doughton
Seattle Times staff reporter

Mount St. Helens' lava dome, seen from Johnston Ridge Observatory early last month, is the state's biggest single source of sulfur dioxide.
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Environmentalists hooted when Ronald Reagan claimed — wrongly — that trees produce more pollution than cars.

But right now, the biggest single source of air pollution in Washington isn't a power plant, pulp mill or anything else created by man.

It's a volcano.

Since Mount St. Helens started erupting in early October, it has been pumping out between 50 and 250 tons a day of sulfur dioxide, the lung-stinging gas that causes acid rain and contributes to haze.

Those emissions are so high that if the volcano was a new factory, it probably couldn't get a permit to operate, said Clint Bowman, an atmospheric physicist for the Washington Department of Ecology.

All of the state's industries combined produce about 120 tons a day of the noxious gas.

The volcano has even pulled ahead of the coal-fired power plant near Centralia that is normally the state's top air polluter. In the mid-1990s, when the facility's emission rate was about 200 tons a day, regulators pressed for $250 million in pollution controls to bring it down to today's level of 27 tons.

Government doesn't wield much power over a volcano, though.

"You can't put a cork in it," said Greg Nothstein, of the Washington Energy Policy Office.

Because the area around St. Helens is so sparsely populated, officials say they haven't heard complaints about respiratory problems linked to the emissions. But if the volcano were right next to Seattle or Portland, some of the most sensitive residents would probably feel the effects, said Bob Elliott, executive director of the Southwest Clean Air Agency in Vancouver.

"We are very fortunate, in terms of the impact on human health, that Mount St. Helens is pretty remote."

Italy's Mount Etna can produce 100 times more sulfur dioxide than Mount St. Helens — and sits in the middle of a heavily populated area. The volcano spawns acid rain and a type of bluish smog that volcanologists call vog, which can affect large swaths of Europe, said Terry Gerlach, a U.S. Geological Survey scientist who studies volcanic gases.

Kilauea Volcano on Hawaii's Big Island churns out 2,000 tons a day of sulfur dioxide when it's erupting, creating an acid fog that damages local crops. The 1991 eruption of Mount Pinatubo in the Philippines blew out so much of the gas that the resulting haze spread around the globe and lowered average surface temperatures in the Northern Hemisphere by nearly one degree.

Some localized impacts are probably occurring on a much smaller scale near St. Helens' crater, Gerlach said.

"If you were to go and collect rainwater just downwind of the volcano, I suspect you would see some acid rain."

Worldwide, sulfur dioxide emissions from volcanoes add up to about 15 million tons a year, compared to the 200 million tons produced by power plants and other human activities.

While the fraction due to volcanoes is small, it can have an impact, Gerlach said.

"You can't call it trivial, compared with human activity."

Volcanic gases bubble out of magma as it rises to the surface, and the amount and type of emissions depend on the chemical makeup of the molten rock. In addition to sulfur dioxide, volcanoes also release smaller amounts of other noxious gases, including hydrogen sulfide and hydrogen chloride.

And they churn out large quantities of carbon dioxide. Though not considered an air pollutant, carbon dioxide is the so-called greenhouse gas that's primarily blamed for global warming.

Compared to man-made sources, though, volcanoes' contribution to climate change is minuscule, Gerlach said.

Mount St. Helens produces between 500 and 1,000 tons a day of carbon dioxide, he estimates.

Nothstein, of the state energy office, says the Centralia coal plant puts out about 28,000 tons a day. Statewide, automobiles, industries, and residential and business heating systems emit nearly 10 times that amount.

On a global scale, the difference is even more dramatic, said Gerlach, who often gets calls from power-plant operators and oil-company executives who believe nature is just as responsible for global warming as man. His answer always disappoints them.

"I tell them the amounts don't even come close and I usually never hear from them again."

Worldwide, people and their activities pump 26 billion tons of carbon dioxide into the atmosphere, he said. The total from volcanoes is about 200 million tons a year — or less than 1 percent of the man-made emissions.

The irony of being surpassed by a volcano on the state's pollution source list hasn't escaped the folks at the Centralia power plant, owned by the Canadian firm TransAlta.

"I hope they're going to call Mother Nature and have her put some scrubbers on there," joked company spokesman Richard DeBolt.

In a way, that will happen, said Bowman, the Ecology Department atmospheric scientist.

As wet winter storms sweep through the area, the rainwater acts as a natural scrubber, washing the sulfur dioxide from the air.

And once the volcano stops erupting, the gas emissions will vaporize — but geologists say the current lava flows could continue for months, or even years.

Sandi Doughton: 206-464-2491


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