Depending on the occupation or specific activities in an occupation, prolonged exposure to occupational “noise” can have adverse impacts on the hearing of an employee. Examples of work activities that could cause adverse impacts to employee hearing include the noise from a stamping machine, jackhammering, pounding with a hammer, operation of hand-held electronic tools, drilling, operation of a generator or other engines/machinery, and an aircraft marshaller. among other activities or occupations. Because of these potential adverse impacts to the hearing of an employee, the Occupational Safety and Health Administration (OSHA) has established regulations and requirements for “Occupational Noise Exposure” under 29 Code of Federal Regulations (CFR) 1910.95 . Select information found under 29 CFR 1910.95 is summarized as follows. Please review this citation for complete rules. To assist in compliance with OSHA’s regulations, hearing hazards and hearing protection should be addressed in your Job Safety Analysis (JSA) or Job Hazard Analysis (JHA).
Under 29 CFR 1910.95(c), an employer is required to have a continuing and effective hearing conservation program for its employees whenever employee noise exposures in the workplace equal or exceed an eight-hour time-weighted average sound level (TWA) of 85 decibels average (dBA) measured on the A scale (slow response) , or, equivalently, a dose of 50 percent (%). This 85 dBA limit, referred to as the “action level”, is evaluated without regard to any attenuation of noise provided by personal protective equipment (PPE).
Some factors which could suggest that noise exposures in the workplace may exceed the action level include employee complaints about the loudness of noise, indications that employees are losing their hearing, or noisy conditions which make normal conversation difficult. The employer should also consider any information available on noise emitted from specific machines. To determine if exposures are at or above this action level, it may be necessary to measure or monitor the actual noise levels in the workplace and to estimate the noise exposure or "dose" received by employees during the workday. The results from measuring actual workplace noise can suggest whether a monitoring program should be initiated.
The two primary instruments used to measure noise exposures include the sound level meter and the dosimeter. A sound level meter is a device that measures the intensity of sound at a given moment. Since sound level meters provide a measure of sound intensity at only one point in time, it is generally necessary to take several measurements at different times during the day to estimate noise exposure over a workday. If noise levels fluctuate, the amount of time noise remains at each of the various measured levels must be determined.
A dosimeter is like a sound level meter except that it stores sound level measurements and integrates these measurements over time, providing an average noise exposure reading for a given period, such as an eight-hour workday. With a dosimeter, a microphone is attached to the employee's clothing and the exposure measurement is simply read at the end of the desired period. A separate reader unit may be used to read-out the dosimeter's measurements. Since the dosimeter is worn by the employee, it measures noise levels in those locations in which the employee travels. A sound level meter can also be positioned within the immediate vicinity of the exposed worker to obtain an individual exposure estimate. Such procedures are generally referred to as "personal" noise monitoring.
Area monitoring can be used to estimate noise exposure when the noise levels are relatively constant, and employees are not mobile. In workplaces where employees move about in different areas or where the noise intensity tends to fluctuate over time, noise exposure is generally more accurately estimated by the personal monitoring approach. The Job Safety Analysis or Job Hazard Analysis document is a great place to outline the job or task’s hearing conservation monitoring requirements and can be used as a discussion topic in your daily tool box talks.
Regardless of the meter used, both the dosimeter and sound level meter should be maintained, and calibrated following procedures outlined in the respective owner’s manual. Both types of meters should be calibrated before and after each use.
Whatever strategy that an employer uses to develop and implement a noise monitoring program, the sampling strategy should be designed to identify employees to be included in the hearing conservation program and to ensure the selection of proper and adequate hearing protectors, per 29 CFR 1910.95(d)(1)(i). As indicated in 29 CFR 1910.95(d)(3), re-monitoring of noise levels must be conducted when there are significant changes in machinery/equipment, production processes, or controls that may result in increased noise exposures resulting in:
- additional employees who may be exposed at or above the action level, and/or
- the attenuation provided by hearing protectors in use by the employees may be rendered inadequate to meet the requirements of the rule.
Many companies choose to re-monitor periodically (once every year or two) to ensure that all exposed employees are included in their hearing conservation programs. Per 29 CR 1910.95(e), the employer shall notify each employee exposed at or above the action level of their respective monitoring results.
If the results of employer monitoring indicate that any employee is exposed to noise at or above the action level, the employer could mitigate the noise exposure through engineering and/or administrative controls. If engineering and/or administrative controls are not feasible, the employer shall establish and maintain an audiometric testing program and make audiometric testing available to the impacted employee(s) at no cost to the employee(s). Per 29 CFR 1910.95(g)(5)(i), within six months of an employee’s first exposure at or exceeding the action level, the employer shall establish a valid baseline audiogram against which to compare subsequent audiograms. After obtaining the baseline audiogram, the employer shall obtain a new audiogram for the employees affected at or above the action level at least annually. Before the baseline and subsequent audiometric tests, the affected employee shall avoid workplace noise or high levels of non-occupational noise at least 14 hours immediately preceding the test.
Audiometric tests shall be conducted by a licensed or certified audiologist, otolaryngologist, or other physician, or by a technician who is certified by the Council of Accreditation in Occupational Hearing Conservation, or who has satisfactorily demonstrated competence in administering audiometric examinations, obtaining valid audiograms, and properly using, maintaining, and checking calibration and proper functioning of the audiometers being used. A technician who operates microprocessor audiometers does not need to be certified. A technician who conducts audiometric tests must be responsible to an audiologist, an otolaryngologist, or a physician.
If noise monitoring indicates that any employee is exposed to noise at or above the action level, in addition to participation in an audiometric testing program, the employer shall make Personal Protection Equipment (PPE), such as hearing protectors, available at no cost to the affected employee(s). Employees shall be given the opportunity to select their hearing protectors from a variety of suitable hearing protectors provided by the employer. The employer is responsible for ensuring that hearing protectors are worn by employees required to wear hearing protection, or employees who are exposed to noise at or exceeding the action level who have yet to receive a baseline audiogram. The employer also is responsible for providing training in the use and care of all hearing protectors provided to employees, for ensuring the proper initial fitting of all hearing protectors and for supervising their correct use, and for replacing hearing protectors, as necessary.
As used in 29 CFR 1910.95(g)(10), a “standard threshold shift” occurs when there is a change in an employee’s hearing of 10 decibels (dB) or more at 2000, 3000, or 4000 hertz (Hz) in either ear. In determining whether a “standard threshold shift” has occurred, allowance may be made for the contribution of aging to the change in hearing level by correcting the annual audiogram according to the procedure summarized in Appendix F of 29 CFR 1910.95 . If a physician determines that the “standard threshold shift” is related to the affected employee’s work activities, then the employer should take the following steps:
- Employees not using hearing protection shall be fitted with hearing protectors, trained in their use and care, and required to use the protectors.
- Employees already using hearing protectors shall be re-fitted and re-trained in the use of hearing protectors, and provided with hearing protectors offering greater attenuation, if needed.
- The employee shall be referred for a clinical audiological evaluation or an ontological examination, as appropriate, if additional testing is necessary or if the employer suspects that a medical pathology of the ear is caused or aggravated by the wearing of hearing protectors.
- The employee is informed of the need for an ontological examination if a medical pathology of the ear is suspected that is unrelated to the use of hearing protectors.
Per 29 CFR 1910.95(k), the employer is responsible for maintaining and ensuring employee participation in a training program in which the employer shall train each employee who is exposed to noise at or above the action level in accordance with the requirements of 29 CFR 1910.95. The training program shall be repeated annually for each employee included in the hearing conservation program. Information provided in the training program shall be updated to be consistent with changes in PPE and work processes.
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