1.5 inches (about 3.8 centimeters) without tapering, which pose a significant hazard to motorcycles. Potholes and presence of debris pose a greater hazard for motorcyclists than drivers of larger vehicles, because the former can cause a loss of stability and control and the latter can deflect a motorcycle's wheel at impact. Motorcycle deaths and military personnel Data from the Iraq War era showed that United States military veterans returning from Southwest Asia combat areas were dying in motorcycle related fatalities. Between October 2007 and October 2008, 24 active-duty Marines died from motorcycle accidents. There were 4,810 deaths on motorcycles in the U.S. in 2006, an increase of 5 percent over the previous year, and more than double (2,161) over the decade before, according to the National Highway Traffic Safety Administration (NHTSA). In the Marine Corps, high-speed bikes accounted for the majority of fatalities. In 2007, 78 percent of motorcycle mishaps in the Marines occurred on a sport bike, compared to 38 percent nationally. In a chapter of Coming and Going on Bikes, Iraq War veteran and author Jack Lewis observed combat veterans' disordered perception of risk, resulting in nearly suicidal behavior: "We already walked through the world's worst neighborhoods with bullseyes painted on our chests... the most at-risk riders in the military community are risk-tolerant, adrenaline-juicing combat professionals." Consequences of accidents Once the collision has occurred, or the rider has lost control through some other mishap, several common types of injury occur when the bike falls: Collision with less forgiving protective barriers or roadside "furniture" (lampposts, signs, fences, etc.). Note that when one falls off a motorcycle in the middle of a curve, lamps and signs become impossible to negotiate around. Concussion and brain damage, as the head violently contacts other vehicles or objects. Riders wearing an approved helmet reduce the risk of death by 37 percent. Breakage of joints (elbows, shoulders, hips, knees and wrists), fingers, spine and neck, for the same reason. The most common breakages are the shoulder and the pelvis. Soft tissue (skin and muscle) damage (road rash) as the body slides across the surface. This can be prevented entirely with the proper use of motorcycle-specific protective apparel such as a leather jacket or reinforced denim and textile pants. There is also a condition known as biker's arm, where the nerves in the upper arm are damaged during the fall, causing a permanent paralysis of arm