What is the merit of following two methods?
a. OSHA currently has a permissible exposure limit (PEL) for noise of 90 dBA as an eight-hour time weighted average (TWA) exposure with an action level of 50% of that exposure. OSHA uses a 5 dB exchange rate (doubling rate);
b. NIOSH and ACGIH recommend using an exposure limit of 85 dBA instead of 90 dBA and also recommend using a 3 dB exchange rate.