Abstract: At 11:30 a.m. on August 17, 2017, Employee #1 and Coworker #1, employed by a construction company, were working with fellow crewmembers at an existing multifamily residential complex. They were performing renovations to one of the four buildings. The work included removing rotted wood trim and replacing exterior siding. The workers were installing Hardie Board siding that measured 8 inches by .25 inch by 12 feet. The crew used a Mag 77 circular saw to cut the siding to the needed length. Employee #1 used a Hitachi NV 65AH2 pneumatic nail gun to fasten the siding to the structure. The nail gun operated at approximately 60 to 70 psi and dispensed nails approximately 2 inches long via a single sequential actuation mechanism or a contact actual mechanism, which in both modes required the operator to pull the trigger. As Employee #1 was operating the nail gun, Coworker #1, as he exited the work area, inadvertently caught his foot on the hose supplying air to the nail gun. Coworker #1's foot pulled the hose, and the nail gun turned toward Employee #1's body. The tip of the nail gun pressed against Employee #1's chest area, and a nail was dispensed into his left chest cavity. Emergency services were called, and Employee #1 was transported to the hospital. He was admitted, the nail was removed from his chest, and the puncture wound treated.