The problem of slow or incomplete wound healing associated with exposure to cigarette smoke was clearly demonstrated in laboratory animals in the 1970's. Then surgeons began reporting on similar problems in patients who smoked: larger scars in women undergoing exploratory abdominal surgery, more complications and skin sloughing after face lifts and a much higher failure rate of skin grafts. Cigarette smoking constricts surface blood vessels, reduces the oxygen level in the blood, thickens the blood and impedes the laying down of collagen needed for healing.