 While point sources of pollution were studied since the late nineteenth century, linear sources did not receive much attention from scientists until the late 1960s, when environmental regulations for highways and airports began to emerge.At the same time, computers with the processing power to accommodate the data processing needs of the computer models required to tackle these one-dimensional sources became more available.In addition, this era of the 1960s saw the first emergence of environmental scientists who spanned the disciplines required to accomplish these studies.