Abstract: At approximately 1:30 p.m. on October 5, 2007, Employee #1 was working on the lower level of a construction site in Burlingame, CA, when he went up to the first floor to look for a choker or wire rope. He saw a choker on the south side of the building, and a coworker welding on the first floor spoke with him briefly as Employee #1 made his way toward the choker. As he approached the area, Employee #1 stepped on the corner of a 4 ft by 8 ft piece of plywood lying on the deck. The plywood dislodged and Employee #1 fell approximately 19 ft through a 16 in. by 83 in. floor opening, landing on the lower level. The coworker later stated that he had seen a corner of the plywood flying into the air, went over to it, and saw Employee #1 lying on the floor. He sustained injuries but did not require hospitalization. The floor opening was labeled correctly, but the plywood was not secured and it did not extend at least 12 in. beyond the perimeter of the opening on all sides.