Reducing Noise on the Jobsite
The National Institute of Occupational Safety and Health (NIOSH) recommends that job sites limit the exposure of workers to no more than 85 decibels for eight hours of work. While this standard protects against long-term damage, many companies attempt to keep noise at even lower levels over extended times. Noise levels that reach a peak of 140 decibels cause immediate hearing damage. After identifying noise sources, job site supervisors can eliminate unnecessary noise sources, substitute quieter equipment, and use engineering controls to reduce noise levels. Along with incorporating these methods, employers and supervisors should enforce the wearing of proper hearing protection by workers at all times.
Identify Noise Sources
A job site inspection can find sources of excessive noise and determine which employees have the most exposure to noise. In some instances, equipment produces noise above acceptable levels; in others, certain processes expose workers to unnecessary levels of noise. While this inspection should occur at the supervisory or administrative level, it may also include safety managers and employees who work in affected areas. Inspections should result in an inventory of activities or equipment which generate noise levels that could present a risk of hearing loss. While preliminary job site surveys often disclose sources of noise, a more thorough assessment may require the use of equipment that can more precisely measure noise levels.
Substitute Quieter Equipment
NIOSH has worked with manufacturers and vendors to develop quieter power tools and to educate firms about the benefit of reducing noise levels on job sites. The “Buy Quiet” program encourages companies to purchase or rent quieter machinery or tools and advertises manufacturers that design quieter equipment. To accomplish noise control, manufacturers can apply precise tolerances, use different gearing or motor arrangements, or implement different cooling options.
As an example, NIOSH compares circular saws producing 107 dba and 96 dba noise levels and demonstrates that the lower decibel rating reduces noise levels by 90 percent. Blades for the circular saw may include vibration dampeners and have smaller gullets to achieve even greater noise reduction. On a larger scale, quieter generators may have improved intake and cooling systems as well as dampeners inside the enclosure.
Seek Engineering Controls
Companies can implement physical engineering controls (such as using barriers) to interrupt noise transmission paths, maintaining lower noise levels for workers. Using the results of a job site survey as a guide, companies can install enclosures around noisy areas or use sound absorbing materials throughout the workplace. Surveys may also indicate the need to modify equipment to dampen vibrations, repair equipment to eliminate metal-on-metal noise, or move equipment to different locations. Maintenance routines aimed at noise reduction may involve regular lubrication or refastening loose shields or guards.
Apply Administrative Controls
Administrative controls involve changing processes or work patterns to reduce exposure to noise sources. Because some practices or tools cannot limit intense noise, supervisors may opt to limit the amount of time that an individual uses the equipment or works in proximity to the area. Work scheduling may rotate workers away from high noise levels or move practices that result in unacceptable noise levels to off-times, when fewer workers are present at the jobsite. Other administrative controls include training, the implementation of quiet areas, and posters or tags that warn about noise levels at specific locations.
Use Personal Protective Equipment
Especially when it comes to the construction industry, unacceptable noise levels are an unfortunate reality. However, wearing personal protective equipment, such as expandable foam plugs, reusable molded plugs, canal caps, and ear muffs, is the best way to protect workers against noise exposure. Any of these PPE should include a noise reduction rating (NRR) that indicates how much it can protect hearing.