OSHA's head protection regulation (29 CFR 1910.135) requires "each affected employee [to] wear protective helmets in areas where there is a potential for injury to the head from falling objects." Hundreds of workers suffer disabling head injuries each day on the job. There are three main causes of job-related head injuries: falling or flying objects that strike or penetrate the head, bumping the head against a fixed object, electrical shock or burns.