Mass transit noise exposure has the potential to exceed limits recommended by the World Health Organization and the US Environmental Protection Agency and thus cause noise-induced hearing loss among riders of all forms of mass transit given sufficient exposure durations. Here are the conclusions of an article published on Jun 18, 2009 in the American Journal of Public Health.In order to measure noise levels associated with various forms of mass transit and to compare them to exposure guidelines designed to protect against noise-induced hearing loss, a team of scientists from the University of Washington and the Columbia University Department of Sociomedical Sciences used noise dosimetry to measure time-integrated noise levels in a representative sample of New York City mass transit systems (subways, buses, ferries, tramway, and commuter railways) aboard transit vehicles and at vehicle boarding platforms or terminals during June and July 2007. The results ? "Of the transit types evaluated, subway cars and platforms had the highest associated equivalent continuous average (Leq) and maximum noise levels, explained the team. All transit types had Leq levels appreciably above 70 A-weighted decibels, the threshold at which noise-induced hearing loss is considered possible." So, the scientists gave some recommendations : "Environmental noise–control efforts in mass transit and, in cases in which controls are infeasible, the use of personal hearing protection would benefit the ridership’s hearing health."Source : Noise Levels Associated With New York City’s Mass Transit Systems. Richard Neitzel, Robyn R.M. Gershon, Marina Zeltser, Allison Canton, Muhammad Akram. American Journal of Public Health,