What is a safe noise exposure level for the public?

What is a safe noise exposure level for the public? This question should underlie basic and applied research on the effects of sound on humans, and regulatory efforts to control public noise exposure. The safe public noise exposure level cannot be an unadjusted occupational standard. Unlike other occupational exposures, noise exposure continues outside the workplace. Occupational limits must be adjusted for increased exposure time, from 8 to 24 hours daily, 240 workdays to 365 days annually, and from 40 work years to the entire lifespan. Recommended safe noise exposure levels depend on which adverse noise effect is being considered. To prevent hearing loss, the U.S. Environmental Protection Agency (EPA) adjusted the U.S. occupational recommended exposure level of 85 A-weighted decibels for additional exposure time to calculate a 70 decibel time weighted average (TWA) exposure level. EPA did not adjust for lifespan years so the correct safe exposure level is likely lower. The World Health Organization (WHO) also recommends 70 decibels to prevent hearing loss. EPA and WHO determined that non-auditory health impacts of noise occur at 55 decibels TWA, with annoyance starting at 45 decibels. These are the safe noise exposure levels for the public.