Ash fall from volcanic eruptions is a major problem for folks who live in the areas impacted by these eruptions. I used to think of ash fall like snow. But its not snow - volcanic ash is tiny jagged pieces of rock and glass. Its hard (you can't use a snowblower to get rid of it, it'll wreck your blower), abrasive, mildly corrosive, conducts electricity when wet, and does not dissolve in water. Think about that - when it rains you don't get the ash washed away - you just get icky mud. Its a major problem.
Also be sure to check out the Alaska Volcano Observatory's page on Mt. Redoubt's activity.