The preservation of natural resources. In 1969 the National Environment Policy Act of 1969 stated that such protection is the responsibility of the federal government, and it was with this in mind that the Environmental Protection Agency (EPA) was formed in 1970. Since then a network of environmental laws has been passed, covering such areas as the quality of air and water, toxic wastes, endangered species, and pesticides. See also greenhouse effect; ozone layer; toxic wastes.