Abstract: At about 5:00 a.m. Employee #1, a security guard employed by a guard service firm, was on duty at a hotel and restaurant and making his rounds. He heard an unusual noise from an enclosed area next to the hotel. This area was enclosed by a solid board wall about 10 ft high. There was an opening where boards had been removed. Employee #1 entered to investigate. He stepped into the area onto metal grating and fell through the old and badly rusted grating into an air shaft. He fell about 15 ft to a concrete floor. Employee #1 required hospitalization. This area is an exhaust area from the hotel and restaurant ventilation system.