Abstract: At approximately 7:40 a.m. on April 2, 2004, Employee #1, a site technician for a health and science company, was working at a construction site performing air sampling. He was the only employee at the jobsite. Employee #1 setup his air sampling equipment on the outside of a building and attempted to feed power to it by running an extension cord through the first floor window of the building's opening. Around the perimeter of the same building, there was an erected metal scaffold. As Employee #1was on the ground pulling the cord, it got stuck. He stepped onto the cross bracing of the scaffold and attempt to free the jammed cord. Employee #1 fell about 16 inches onto the ground and broke his right ankle. Emergency services were contacted and Employee #1 was taken to UCSF Medical Center where he was treated for a broken ankle, which required surgery. A detailed investigation revealed that the cross bracing came loose from its pin.