Fiftieth anniversary of the Environmental Protection Agency's “noise levels” monograph

In 1974, as mandated by Congress in the Noise Control Act of 1972, the Environmental Protection Agency (EPA) published Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety. The Foreword stated, “not all of the scientific work that is required for basing such levels of environmental noise on precise objective factors has been completed…Nonetheless, there is information available from which extrapolations are possible and about which reasoned judgments can be made.” Based on then-available science, the EPA calculated that the noise level to prevent hearing loss was Leq(24) =< 70 dB; to prevent outdoor activity interference and annoyance Ldn =< 55 dB for areas in which quiet is a basis for use and Leq(24)=< 55 dB for areas in which people spend limited amounts of time; for indoor residential areas Ldn=<45 dB and Leq(24)=<45 dB for other indoor areas. The monograph specified that these numbers were not federal standards. Remarkably, subsequent research published in thousands of peer-reviewed articles, and analyses leading to noise exposure recommendations from the World Health Organization, have largely confirmed the accuracy of the EPA’s fifty-year old calculations. They got it right! This milestone anniversary should be celebrated.