by Katy Ibsen, contributing writer
Over the past two decades, more attention has been given to the effects of increased noise within the manufacturing environment, which can lead to hearing loss. According to the Occupational Safety and Health Administration (OSHA), “noise, or unwanted sound, is one of the most pervasive occupational health problems.
“Noise-induced hearing loss can be temporary or permanent. Temporary hearing loss results from short-term exposures to noise, with normal hearing returning after period of rest. Generally, prolonged exposure to high noise levels over a period of time gradually causes permanent damage,” as stated in OSHA’s Hearing Conservation booklet no. 3074.
As a result, many plastics manufacturers have put an emphasis on protecting employees by complying with OSHA’s hearing conservation program. The program provides industry-specific requirements to protect an employee’s hearing by monitoring noise exposure, providing audiometric testing, providing hearing protection, conducting training and maintaining recordkeeping of results.
To understand a manufacturing facility’s noise exposure, it first must be monitored. American Casting and Manufacturing, a family-owned manufacturer of plastic and metal security seals in Plainview, New York, has maintained an OSHA-compliant hearing conservation program for its production employees for more than 20 years.
“Most of our production area is classified as a high-noise area, and all production employees are required to wear hearing protection throughout the day,” says Christian Wenk, managing partner. “We perform annual hearing tests for all employees who work in the high-noise areas, and we perform full-day noise dosimetry to establish the production areas in which employees will require hearing tests.”
OSHA defines the standard for harmful noise exposure as at or above 85 decibels, averaged over eight working hours, or an eight-hour time-weighted average (TWA). To put that into perspective, a garbage disposal or dishwasher typically generates sound at 80 decibels. A hand-held power tool, belt sander and jigsaw all emit noise at an average of 95 decibels – and, as noise doubles every three decibels, a tool operating at 95 decibels has the potential to be significantly more damaging.
Any employee who is exposed to a level of noise at or above 85 decibels should be evaluated during a typical work situation. If the work situation changes, the evaluation must reoccur to ensure protection is still adequate in relation to the level of noise exposure.
To determine the level of exposure, monitoring is conducted by a series of tests, such as the testing that occurs at American Casting and Manufacturing.
Noise level testing
Baseline noise level information can be gathered from documentation provided by the equipment suppliers from which machinery and tools have been purchased. Additional testing will likely be necessary, however, and OSHA recommends three methods, as quoted from Section III, Chapter 5 of the OSHA Technical Manual:
- Sound level meters provide instantaneous noise measurements for screening purposes. During an initial walkaround, a sound level meter helps identify areas with elevated noise levels where full-shift noise dosimetry should be performed.
- Most sounds are not a pure tone but rather a mix of several frequencies. The frequency of a sound influences the extent to which different materials attenuate that sound. Knowing the component frequencies of the sound can help determine the materials and designs that will provide the greatest noise reduction. Therefore, octave band analyzers can be used to help determine the feasibility of controls for individual noise sources for abatement purposes and to evaluate whether hearing protectors provide adequate protection.
- Like a sound level meter, a noise dosimeter can measure sound levels. However, the dosimeter is actually worn by the worker to determine the personal noise dose during the workshift or sampling period. Noise dosimetry is a form of personal sampling, averaging noise exposure over time and reporting results such as a TWA exposure or a percentage of the permissable exposure limit.
At American Casting and Manufacturing, noise dosimetry testing is utilized. “Dosimetry testing is performed by having employees wear a noise dosimeter through their shift,” Wenk said. “You receive peak noise values as well as noise ‘dose’ for the full shift. This determines whether the employee is exposed to a level of noise that requires them to have annual hearing tests.”
Wenk’s company requires hearing protection for all production employees since much of the facility qualifies as high noise. “Our machine shop, injection molding building and shipping and receiving areas are the exceptions.”
Baseline and annual testing for employees
Audiometric testing specifically monitors an employee’s hearing over time.
The American Speech-Language-Hearing Association (ASHA) recommends audiometric testing be performed by a Council for Accreditation in Occupational Hearing Conservation (CAOHC)-certified audiometric technician. According to a 2010 recommendation to OSHA, ASHA indicated that, “technicians who are CAOHC-certified have demonstrated their competence in pure-tone audiometry and knowledge of the critical factors that influence the accuracy of audiometric testing programs.”
As a result, OSHA recommends using a licensed or certified otolaryngologist, or other physician, to perform audiometric testing for employees exposed to the standard of 85 or more decibels over an eight-hour TWA.
Before annual testing is measured among employees, OSHA recommends a baseline audiogram test for each employee within six months of the employee’s exposure to the standard of 85 or more decibels over an eight-hour TWA. Employees must complete the baseline audiogram within one year of their start date.
Results of the baseline dictate what hearing protection is issued and required for each employee. This is considered a benchmark for each employee, and the employer must not only be transparent with the employee of its results, but also will be responsible for keeping it on record.
Annual testing, if warranted, tests employees against their baseline audiograms to determine whether they have experienced deterioration in their hearing levels. OSHA states, “it is important to test workers” hearing annually to identify deterioration in their hearing ability as early as possible. This enables employers to initiate protective follow-up measures before hearing loss progresses.
In addition to protecting the employee’s hearing, a hearing conservation program also can result in reduced worker’s compensation insurance rates and other injury- or illness-related costs.
As of 2010, noise-induced hearing loss (NIHL) was one of the most common occupational injuries and the second most self-reported occupational illness or injury, according to the National Institute for Occupational Safety and Health. At that time, it was estimated that approximately 22 million American workers were sometimes exposed to high levels of noise on the job.
Employer awareness and programs such as OSHA’s Hearing Conservation Program are helping to reduce these statistics and protect workers.
Learn more about OSHA’s Hearing Conservation program or compliance tools: www.osha.gov