The Occupational Safety and Health Administration (OSHA) currently has a permissible exposure limit (PEL) for noise of 90dBA at an 8-hour time-weighted average (TWA) exposure with an action level of 50% of that exposure. OSHA uses a 5 dB exchange rate (doubling rate); this means that if the exposure increases from 90 dBA to 95 dBA, the allowed exposure time decreases to one-halffrom 8 hours to 4 hours.

The National Institute for Occupational Safety and Health (NIOSH) and the American Conference of Governmental Industrial Hygienists (ACGIH) recommend using an exposure limit of 85 dBA instead of 90 dBA and also recommend using a 3 dBexchange rate. These levels are much more protective than the levels currently used by OSHA.

What are themerits of each of the two methods andapproach should be used? one professional/scholarly min.