Why is this hazard in the classroom?

In your Feb. 20 story on the front page, University Police Department Chief Bill Watton is quoted as saying that “chalk is a hazardous material.” If so, why are there still so many classrooms on campus with chalkboards? Classrooms in building 21, for example, are so choked with decades of chalk dust that you can literally see it floating in the air. Unless you wear a gas mask you can’t avoid breathing it.

Several years of teaching in this environment created in me a severe asthmatic reaction to this material, to the point that I now must be scheduled only in rooms with whiteboards. Speaking for faculty, staff and students: if chalk dust is “hazardous” beneath our feet, why hasn’t something been done about the hazard to our health?