NIOSH Finds Overexposures to Noise at a Precast Concrete Manufacturer

A NIOSH investigation of a precast concrete manufacturing plant found noise overexposures among workers in all the job titles that were monitored. The facility used both drycast and wetcast processes to manufacture precast concrete highway barriers, manholes, and other products. NIOSH’s evaluation of the plant focused mainly on assessing noise during drycast manufacturing, which uses a lower water-to-concrete ratio and involves noise from vibrating machinery, metal-to-metal contact noise from hammers and sledges, and welding. Agency personnel spent two days in the plant to gather information about work processes and workplace conditions and to measure employee noise exposures and noise levels in the production areas.

NIOSH personnel found that drycast operators, wetcast operators, wire operators, quality control mix operators, forklift operators, and supervisors were exposed to noise levels above the NIOSH recommended exposure limit of 85 dBA for an eight-hour shift. Drycast operators, wetcast operators, and wire operators were exposed to noise levels above OSHA’s action level of 85 dBA, and one drycast operator was exposed to noise levels above the OSHA PEL of 90 dBA for an eight-hour day. NIOSH’s health hazard evaluation report stresses that for employees working 10-hour shifts, OSHA reduces its action level to 83.4 dBA and NIOSH reduces the REL to 84.0 dBA. If the employees NIOSH monitored at the plant were working 10-hour shifts, the report states that wetcast operators’ and quality control mix operators’ noise exposures would have also likely been above both the OSHA action level and the NIOSH REL.

NIOSH investigators identified several engineering controls to reduce workers’ noise exposures. The agency’s report urges the employer to isolate or enclose noisy equipment or processes; replace vibratory motors with frequency drive motors, which would allow operators to control the speed and vibration as molds fill with concrete, thus reducing noise levels; and properly adjust and service existing equipment to reduce excess noise. NIOSH also suggests implementing a “Buy Quiet” program to reduce noise by buying new equipment that generates less noise and vibration.

The report also provides recommendations to improve the company’s hearing conservation program. For example, the employer should complete audiometric testing on a regular basis and conduct noise measurement surveys after noise controls are installed.

For more information, download the full report (PDF) from the NIOSH website.