Leaking air conditioning refrigerant prompted the evacuation yesterday of Kaiser Permanente's administrative offices at 711 Kapi'olani Blvd.

Firefighters were sent to the building about 7:20 a.m. in response to a report of smoke in the building.

A light gray haze was visible in the building's lobby at 7:30 a.m. as dozens of office workers waited on the sidewalk outside while firefighters searched for the source of the problem.

Stu Glauberman, a Kaiser spokesman, said later that the smoke was actually refrigerant that had leaked from the building's air conditioning system.

Employees were allowed to return to the building about 8:45 a.m., Glauberman said. Some of them, who work in the patient accounting office, where the problem seemed to originate, were released for the day.