The US EPA was created as an administrative agency in 1970 by the Richard Nixon administration as a compromise against creating an executive level environmental agency. While conservation, pollution and public health agencies have been around for some time, uniting them under one banner was seen as a popular initiative in the 1969 into 1970 brought on by the new found interest in pollution, especially on a national sense after the blue globe photos of NASA Moon Mission, greater suburbianizatiom and professionalism of the working professionals.
The thing is conservation, public health and pollution concerns existed long before 1970, though in some ways the science and technology of the 1950s and 1960s made it much easier and practical to control pollution by the 1970s. Yet it’s not like the change was overnight, it took 55 years to get where we are today with pollution controls – which by no means are perfect. I think it’s a mistake to say nobody in society cared about pollution before 1970, and that everything was perfectly controlled there after. Societies evolve slowly.