Addicts may often enter rehab more or less poisoned, but they rarely expect to exit hurriedly in a far worse condition. Forty-three residents and staff members of a Washington, DC drug-treatment facility were evacuated and taken to hospital Tuesday to be treated for carbon monoxide poisoning—with three of them described as being in serious but non-life-threatening conditions. Emergency responders found several people with symptoms of carbon monoxide poisoning, as well as a “high level” of carbon monoxide in the building, owned by Silver Spring–based rehab Second Genesis. The facility, located in the Columbia Heights neighborhood, accommodates 33 residents and 10 staff members. Second Genesis is a nonprofit abstinence-based treatment center with four locations in the District and Maryland, which has been in operation for more than 40 years. The source of the gas in the three-story facility was a clogged hot water boiler vent that had collapsed due to “recent extreme rain events,” according to a statement released by the rehab. Authorities have "deemed [the building] safe for re-occupancy" pending repairs, said the statement.