text: Mount St. Helens Top Washington Polluter (AP) AP - Washington state's top polluter isn't a pulp mill, a power plant or refinery. It's the newly awakened Mount St. Helens. Since the volcano began erupting in early October, it has been pumping out 50 to 250 tons a day of sulfur dioxide, the lung-stinging gas that causes acid rain and contributes to haze.