The U.S. Environmental Protection Agency's (EPA) ombudsman, Robert J. Martin, is investigating whether the EPA opened the Hart Senate Office Building before it was properly decontaminated. The building, which houses fifty senators and hundreds of staffers, was closed last fall after anthrax spores were discovered inside. Heavy doses of chlorine dioxide were used during the decontamination process.

Since returning to their jobs this week, several employees have complained of headaches and sore throats. Martin is concerned that the lethal doses of chlorine dioxide, which were used on three occasions, "could be in the air for a significant period of time."