The United States Coast Guard is the United States' chief maritime safety regulatory authority, and the Marine Technical and Hazardous Materials Division of the Office of Merchant Marine Safety, among other Coast Guard units, is charged with protecting the merchant fleet and merchant marine personnel from harm. In recent years the Coast Guard has become more involved with the harmful effects of ships' atmospheres, including both acute and chronic effects. Unlike shore workers, the marine worker can not escape his workplace after eight hours, and so occupational problems can be more severe. This paper discusses the work of the Division in several areas of marine worker safety, including asbestos, fire extinguishing gases, cargo vapors, cargo tank atmospheres, noise, radiation, smoke, and human factors. Our goal is to improve the level of safety of the marine worker.