Noise pollution is unwanted or harmful sound that intrudes upon human or other faunal activity. Noise pollution is almost entirely human generated, whether by machine sources or amplified sound of human creation. Approximately ninety percent of all such intrusive sound arises from such transport devices as motor vehicles, aircraft and rail activities. Noise pollution gives rise to an assortment of adverse human health effects as well as disruption of faunal activity. Regulation of noise pollution began in a systematic way in the United States with enactment of the Noise Control Act of 1972. Within the next 22 years a number of other national governments had emulated the U.S. initiative, including Netherlands (1979), France (1985), Spain (1993), and Denmark (1994). Noise pollution can also occur underwater, where man made sound may disrupt communication and echo-location for marine mammals and other fauna.