Comparison of daily noise exposures in one workplace based on noise criteria recommended by ACGIH and OSHA.

The objective of this study was to determine the impact of the new American Conference of Governmental Industrial Hygienists (ACGIHnew) noise criteria, as compared to the current U.S. Occupational Safety and Health Administration (OSHA) hearing conservation criteria, on the number of employees to be included in the hearing conservation program at one industrial facility. This study also compares the combined effects of a 3-dB versus a 5-dB exchange rate and an 80-dBA versus a 90-dBA measurement threshold on daily noise doses and equivalent 8-hr time-weighted averages (TWAs). Employee noise exposures were measured using paired Ametek MK-3 noise dosimeters, one dosimeter set to the ACGIHnew noise criteria and one to the present OSHA hearing conservation criteria. Samples were collected over 4-hr periods (half-shifts) for 50 employees in 7 job categories. Results indicate that the majority of the employees' exposures fell below an 8-hr TWAOSHA of 85 dBA. The differences between the predicted TWAACGIHnew and the TWAOSHA ranged between 0.2 and 12.6 dB for paired samples, with an average difference of 4.6 dB. Overall, these differences in employee 8-hr TWAs would project a 36% increase in the percent of the population enrolled in the hearing conservation program and a 50% increase in the percent of the population required to wear hearing protection.