Occupational Hearing Testing
Occupational noise exposure is the most significant health hazard present in the modern industrial workplace. Not only does it impact employees who have suffered permanent hearing loss due to unsafe levels of industrial noise, it also takes a huge bite out of the pocketbooks of employers who must financially compensate affected workers.
According to the Third Edition of Fundamentals Of Industrial Hygiene, published by the National Safety Council, an estimated 1.7 million workers in the U.S. between 50 and 59 years of age have some form of noise-induced hearing loss. Industry experts state that an average claim costs $3,000. If only 10 percent of those workers filed for compensation, the potential cost to industry could exceed $500 million.
As an employer, you need to protect yourself and your company. Preforming baseline testing at the pre-employment stage, as well as throughout your employee’s tenure, provides your company with the results you need to create a safe work environment. It allows you to protect the health and well being of your staff, as well as your company.
Occupational Noise Exposure Standard
As OSHA standards go, the occupational noise exposure standard is a relatively user-friendly document. It’s extremely thorough, thus eliminating much of the reader interpretation that most standards require.
The standard essentially implements a three-pronged approach to addressing industrial noise. The basic components are recognition, evaluation, and control. Additionally, training and record keeping are used to support each of the standard’s basic components. The importance of these elements cannot be underestimated.
How can hearing tests protect my business?
Before determining whether an employee is being exposed to an unsafe level of noise, the level of noise must first be quantified. OSHA identifies 90 decibels (dB) based on an eight-hour time-weighted average (TWA) as the absolute “safe” level of noise exposure. This 90 dB concentration is referred to as the OSHA permissible exposure limit (PEL) for noise exposure. Any eight-hour time-weighted average exceeding 90 dB requires the employer to implement control measures to reduce the exposure to 90 dB or below.
In addition to the 90 dB PEL, OSHA also recognizes an 85 dB time-weighted average as its action level. The action level was established in the 1983 Hearing Conservation Amendment. While employee exposure to the action level does not force an employer to take measures to reduce employee noise exposure, it does require the employer to establish a hearing conservation program. The Hearing Conservation Amendment defines a hearing conservation program in detail. It mandates that the employer conduct noise exposure monitoring, perform audiometric testing on employees, provide hearing protection to employees who request it, conduct employee training, and retain records of the aforementioned activities.
How Do I Know If My Work Place Is Noise Safe?
Under 29 CFR 1910.95(d), OSHA states noise levels must be monitored, “when information indicates that any employee’s exposure may equal or exceed an eight-hour time-weighted average of 85 decibels.” As a general rule of thumb, if an individual’s voice must be raised to converse at a distance of three feet, the noise level probably exceeds 85 dB. At the very least, this is an indication that monitoring should be conducted.
Two basic types of instruments are available to monitor noise levels: sound level meters and noise dosimeters. Both instruments measure in decibels. It’s important to note that decibels are not linear units like feet or pounds. The decibel is a dimensionless unit that expresses a logarithmic ratio to an established reference level. To put the decibel into perspective, remember that while a reading of 10 decibels is 10 times greater than one decibel, a reading of 20 decibels is 100 times greater (10 x 10) than one decibel, and a reading of 30 decibels is 1000 times greater (10 x 10 x 10). This logarithmic ratio is similar to the Richter scale used to measure earthquakes.
Both sound level meters and noise dosimeters are usually capable of measuring decibels in two or three different frequency scales. Frequency refers to the number of vibrations per second a noise contains. It is measured in hertz (Hz). The frequency scales are known as the A scale, the B scale and the C scale. OSHA requires that noise measurements be conducted using the A scale, which most closely resembles the human ear.
Sound level meters are direct reading instruments that provide a “snap shot” measurement of noise levels at a particular time. They do not average noise levels to provide the eight-hour time-weighted average on which OSHA bases its exposure levels. Because of this, sound level meters are most appropriate for preliminary noise surveys to determine if any work areas exceed the 85dB action level. If these areas are identified, then a noise dosimeter can be used to determine an employee’s time-weighted average exposure.
Noise dosimeters are physically worn by employees for an entire work shift in order to record exposure levels. These levels are used to calculate an employee’s time-weighted average exposure.
In terms of calibrating these instruments, the OSHA standard is very vague. It states the instruments, “shall be calibrated to ensure measurement accuracy” (29 CFR 1910.95(d)(2)(ii)). For more specific guidance concerning calibration, refer to the manufacturer’s instructions for the instrument.
After the initial noise monitoring, OSHA requires that additional monitoring be performed whenever there is a change in the production process that may increase noise exposure. It is also required that the employer document all noise exposure measurements and retain these records for at least two years.
Should the noise level monitoring determine that employees are being subjected to levels equaling or exceeding the 85 dB action level, the next step is to establish an audiometric testing program for those exposed. In addition, the employer must provide hearing protectors (e.g., earmuffs or ear plugs) at no cost and institute a training program for all affected employees. According to OSHA, the training program must be conducted annually and ensure that the employees are informed of, “the effects of noise on hearing; the purpose of hearing protectors; the advantages, disadvantages, and attenuation of various types of hearing protectors; instructions on their selection, fitting, use and care; the purpose of audiometric testing; and an explanation of the test procedures.”