Washington State Department of Ecology Sulfur Dioxide Background Sulfur dioxide is a colorless liquid or gas with a very strong odor.
Sulfur dioxide is most toxic when combined with small particles and moisture.
Sulfur dioxide that mixes with water drops in the atmosphere can result in acid rain. The conversion of sulfur dioxide to sulfate particles is also considered a significant problem. However, relatively high levels of sulfur dioxide are occasionally recorded near large industrial facilities in the state. The coal-fired power plant near Centralia is a major contributor of sulfur dioxide, but has recently agreed to a plan that will reduce its sulfur dioxide emissions 90 percent by the year 2007. The major health concerns associated with high exposures to sulfur dioxide include effects on breathing and lung illnesses, changes in the lung's ability to defend itself, aggravation of existing respiratory and cardiovascular disease, and death.