NIOSH established the REL for occupational noise exposures to be 85 decibels, A-weighted (dB[A]) as an 8-hour time-weighted average.[14] Occupational noise exposure at or above this level are considered hazardous. The REL is based on exposures at work 5 days per week and assumes that the individual spends the other 16 hours in the day, as well as weekends, in quieter conditions. NIOSH also specifies a maximum allowable daily noise dose, expressed in percentages.