"Helmets for motor vehicle occupants are now being marketed and a mandatory helmet law for these road users has the potential to save 17 times as many people from death by head injury as a helmet law for cyclists without the adverse effects of discouraging a healthy and pollution free mode of transport." – Robinson, 1996 https://www.sciencedirect.com/science/article/pii/0001457596000164
Nevertheless I wear a helmet when cycling. Also helps keep me warm.
