OSHA 1910.95: Occupational Noise Exposure Requirements
When you consider workplace hazards that lead to injuries and illnesses, noise may not come immediately to mind. Prolonged exposure to excessive noise can lead to irreparable hearing loss. But excessive noise in the short term can also lead to health-related consequences. These can include tinnitus, a condition characterized by a ringing in the ears. In turn, these conditions often cause employers to see a loss in productivity and employee morale.
Noise is unwanted sound and is an extensive occupational health problem. More than 30 million Americans are exposed to hazardous sound levels on a regular basis. Unlike many occupational hazards, exposures to harmful sound levels can also occur in recreational settings, homes, almost anywhere. Thus, the effects of a work exposure may be aggravated by other activities. To protect hearing, people should take measures to limit or minimize all exposures to harmful sound levels. This can be done by either controlling the sound source by reducing the level, by isolating the source or muffling the sound or by the use of personal protective equipment such as ear plugs or muffs.
Hearing loss occurs in two basic ways: conductive and sensorineural. Conductive hearing loss is caused by a problem with a part of the outer or middle ear. A breakdown or obstruction interferes with sound transmission. This type of hearing loss is common and can often be reversed and hearing restored with appropriate treatment. Sensorineural hearing loss occurs from changes in the receptor hair cells in the inner ear or in the nerves carrying impulses to the brain. This type of hearing loss is usually permanent. Noise-induced hearing loss (NIHL) is sensorineural and is usually permanent.
Occupational Noise Exposure Standard
The PEOSH Occupational Noise Exposure Standard, 29 CFR1910.95, states that “When information indicates that any employee’s exposure may equal or exceed an 8-hour time-weighted average of 85 decibels (dB) the employer shall develop and implement a monitoring program (29 CFR 1910.95(d)).
According to OSHA Regulation 29 CFR 1910.95, no worker can be exposed to noise greater than 90 decibels for eight hours during a workday. This standard takes into account that the noise in any given workplace may be higher or lower than 90 decibels. OSHA Regulation 29 CFR 1910.95 establishes the maximum allowable time that a worker can be exposed to noise at a certain decibel. At the low end, workers cannot be exposed to noise of 90 decibels for longer than an average of eight hours during a workday. At the upper end of the regulations, workers are not permitted to be exposed to noise of 115 decibels for more than 15 minutes in a workday. The regulation goes on to say that when workers are exposed to noise exceeding these limitations, measures must be taken to reduce that exposure.
(a) Protection against the effects of noise exposure shall be provided when the sound levels exceed those shown in Table G-16 when measured on the A scale of a standard sound level meter at slow response.
The Occupational Noise Exposure Standard requires that protection against the effects of noise exposure be provided when sound levels exceed those shown in the following table when measured on the “A” scale of a standard sound level meter at slow response. The standard requires that feasible administrative or engineering controls be utilized when levels exceed those listed. If these controls fail to reduce the sound level to those listed, personal protective equipment must be provided and used to reduce sound levels to within the levels of the table.
(1) When employees are subjected to sound exceeding those listed in Table G-16, feasible administrative or engineering controls shall be utilized. When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. If the sum of the following fractions: C1/T1 + C2/T2 C n/T n exceeds unity, then, the mixed exposure should be considered to exceed the limit value.
Hearing Conservation Program
The OSHA hearing conservation standard is set out in OSHA Regulation 29 CFR 1910.95(c)(1) and (c)(2). OSHA hearing conservation programs must also monitor workplace noise.
(c) Hearing conservation program. (1) The employer shall administer a continuing, effective hearing conservation program, as described in paragraphs (c) through (o) of this section, whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.
All University employees whose noise exposures equal or exceeds an eight-hour time weighted average (TWA) of 85 decibels are enrolled in a hearing conservation program.
Noise Exposure Monitoring
When information indicates that any employee’s exposure may equal or exceed an 8-hour time-weighted average of 85 decibels, the department is to notify the Health and Safety Office to implement a monitoring program. The noise survey is performed using a sound level meter (A-scale, slow response) and/or noise dosimeter for evaluation of personal exposures. The employee is to be notified when he/she is exposed at or above an 8-hour time-weighted average of 85 decibels.
The three most common methods of noise monitoring are area surveys, personal dosimetry and engineering surveys. In an area survey, a sound level meter is used to measure environmental noise levels. This information may be used to identify areas where more thorough noise exposure evaluation is needed. Personal dosimetry, a method of evaluating an employee’s individual exposure, is used to determine the noise levels experienced by employees throughout the work shift. A noise measuring instrument with the microphone positioned in the employee’s hearing zone is used to measure sound levels. OSHA defines the “hearing zone” as a two-foot sphere around the employee’s head. This type of monitoring result can also represent the exposure of other workers whose exposures result from the same tasks. During engineering surveys, octave band analyzers and sound level recorders are used to obtain information on the frequency/intensity composition of noise.
Noise Monitoring: Equipment and Procedures
Basically, there are two different instruments to measure noise exposures: 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 a number of measurements at different times during the day to estimate noise exposure over a workday. To estimate employee noise exposures with a sound level meter it is also generally necessary to take several measurements at different locations within the workplace. After appropriate sound level meter readings are obtained, people sometimes draw “maps” of the sound levels within different areas of the workplace. By using a sound level “map” and information on employee locations throughout the day, estimates of individual exposure levels can be developed.
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 of time, such as an 8-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 time period. A reader 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.
Area monitoring can be used to estimate noise exposure when the noise levels are relatively constant and employees are not mobile. In situations where personal monitoring is appropriate, proper positioning of the microphone is necessary to obtain accurate measurements. With a dosimeter, the microphone is generally located on the shoulder and remains in that position for the entire workday. Manufacturer's instructions, contained in dosimeter and sound level meter operating manuals, should be followed for calibration and maintenance.
Frequency of Monitoring
The amendment requires that when there are significant changes in machinery or production processes that may result in increased noise levels, remonitoring must be conducted to determine whether additional employees need to be included in the hearing conservation program.
Equipment and Technical Advice
Noise monitoring equipment may be either purchased or rented. Sound level meters cost about $500 to $1,000, while dosimeters range in price from about $750 to $1,500. Smaller companies may find it more economical to rent equipment rather than to purchase it. Names of equipment suppliers may be found in the telephone book (Yellow Pages) under headings such as: “Safety Equipment,” “Industrial Hygiene,” or “Engineers-Acoustical.” In addition to providing information on obtaining noise monitoring equipment, many companies and individuals included under such listings can provide professional advice on how to conduct a valid noise monitoring program. Some audiological testing firms and industrial hygiene firms also provide noise monitoring services. Free, on-site assistance may be obtained from OSHA-supported state and private consultation organizations.
Paragraphs (c) through (o) of 29 CFR 1910.95 and the accompanying appendices contain provisions which incorporate publications by reference. Generally, the publications provide criteria for instruments to be used in monitoring and audiometric testing. It should be noted that OSHA does not require that employers purchase a copy of the referenced publications.
- “List of Personal Hearing Protectors and Attenuation Data,” HEW Pub. No. 76-120, 1975.
The referenced publications (or a microfiche of the publications) are available for review at many universities and public libraries throughout the country.
Employee notification. Observation of monitoring.
Administrative and Engineering Controls
When employees are subjected to sound levels exceeding 85 dBA TWA, feasible administrative or engineering controls are to be utilized. Types of administrative controls are rotation of employees, limiting time of certain operations, or restricting areas or work operations.
Administrative and engineering controls can be used to reduce exposures to the point where the hazard is eliminated or reduced to manageable proportions. These control measures consist of removing the worker or removing the hazard. This may be accomplished by substituting less noisy equipment for instance. Administrative controls include work scheduling and task assignment. Individual employee exposure is reduced by decreasing the amount of time spent in a noisy environment. Engineering controls include mufflers, sound barriers, enclosures, and sound absorbing materials.
First, employers can consider creating a safe, quiet place away from excessive noise where employees can go as needed to rest their ears. This reduces the total amount of time each day that an employee is exposed to damaging noise levels.
Audiometric Testing Program
Annual audiometric testing is performed by a licensed or certified audiologist, at UNC School of Medicine’s Speech and Hearing department. A baseline audiogram is obtained within 6 months of an employee’s first exposure at or above the action level. The baseline audiogram is established to compare against subsequent audiograms. Audiometric tests are to be pure tone, air conduction, hearing threshold examinations, with test frequencies including as a minimum 500, 1000, 2000, 3000, 4000 and 6000 Hz. Employees are to be notified, in writing, of the results of exams.
Audiometric evaluation is required if employees are exposed to sound levels equal to or exceeding an 8 hour TWA of 85 dB. This evaluation consists of a baseline audiogram obtained within 6 months of an employee’s first exposure to levels of 85dB or greater followed by yearly retesting. The baseline audiogram must be preceded by 14 hours without exposure to workplace noise. The baseline audiogram is then compared to the most recent test to determine if the audiogram is valid and if a standard threshold shift (STS) has occurred in the employee’s hearing. A STS is defined as an average shift from baseline of 10 dB or more in the audiometric frequencies 2000, 3000, and 4000 Hz. In determining whether a STS has occurred an adjustment allowing for the contribution of aging (presbycusis) to hearing loss may be made. The procedure for this adjustment is described in Appendix F of the standard (Calculation and Application of Age Correction to Audiograms). A STS is a sign that the employee has begun to lose hearing and that intervention is needed to prevent further hearing loss. If an STS has occurred, the employer must notify the affected employee in writing within 21 days.
Audiometric tests shall be performed 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.
Mobile test van exception. Where mobile test vans are used to meet the audiometric testing obligation, the employer shall obtain a valid baseline audiogram within 1 year of an employee's first exposure at or above the action level. Testing to establish a baseline audiogram shall be preceded by at least 14 hours without exposure to workplace noise. Annual audiogram. Each employee's annual audiogram shall be compared to that employee's baseline audiogram to determine if the audiogram is valid and if a standard threshold shift as defined in paragraph (g)(10) of this section has occurred. The audiologist, otolaryngologist, or physician shall review problem audiograms and shall determine whether there is a need for further evaluation. Revised baseline.
Audiometric Test Requirements
Audiometric tests shall be pure tone, air conduction, hearing threshold examinations, with test frequencies including as a minimum 500, 1000, 2000, 3000, 4000, and 6000 Hz.
The functional operation of the audiometer shall be checked before each day's use by testing a person with known, stable hearing thresholds, and by listening to the audiometer's output to make sure that the output is free from distorted or unwanted sounds. Audiometer calibration shall be checked acoustically at least annually in accordance with appendix E: Acoustic Calibration of Audiometers. Test frequencies below 500 Hz and above 6000 Hz may be omitted from this check. An exhaustive calibration shall be performed at least every two years in accordance with sections 4.1.2; 4.1.3.; 4.1.4.3; 4.2; 4.4.1; 4.4.2; 4.4.3; and 4.5 of the American National Standard Specification for Audiometers, S3.6-1969.
Hearing Protection
If feasible engineering or administrative controls cannot be accomplished personal hearing protective devices must be provided and used to reduce sound levels in areas above 85 dBA. The hearing protection used will depend on the operation, employee preference and attenuation required. The safety and health officer is to assist in supplying information on attenuation data and supervise the correct use of hearing protectors. Employees are given the opportunity to select their hearing protectors from a variety of suitable hearing protectors. The University strongly encourages the use of hearing protection devices while working around noisy equipment.
Employers shall make hearing protectors available to all employees exposed to an 8-hour time-weighted average of 85 decibels or greater at no cost to the employees. The employer shall evaluate hearing protector attenuation for the specific noise environments in which the protector will be used. The adequacy of hearing protector attenuation shall be re-evaluated whenever employee noise exposures increase to the extent that the hearing protectors provided may no longer provide adequate attenuation.
Personal protective equipment for hearing protection is of two basic types, ear plugs and muffs, and a variety of each type is available. The choice of hearing protection provided should be based on the sound levels present in the workplace where the hearing protection will be used.
For employees who have experienced a standard threshold shift, hearing protectors must attenuate employee exposure to an 8-hour time-weighted average of 85 decibels or below.
Noise Reduction Rating (NRR)
The Noise Reduction Rating (NRR) is a single-number rating method that describes the protection provided by a hearing protector. It indicates how much the overall noise level is reduced by the hearing protector. Field studies by the National Institute for Occupational Safety and Health (NIOSH) have shown that employees normally achieve only about 1/2 of the noise reduction provided by hearing protection. To correctly estimate the noise reduction provided by hearing protection devices, it is important to remember to first subtract 7 from the NRR and then subtract the remainder from the A weighted noise level.
Training Program
The employer shall train each employee who is exposed to noise at or above an 8-hour time weighted average of 85 decibels in accordance with the requirements of this section. The training program shall be repeated annually for each employee included in the hearing conservation program.
Recordkeeping
Employee exposure measurements and assessments are maintained at the office of Environment, Health and Safety. Employee audiometric test records are kept at the University Employee Occupational Health Clinic.
Exposure measurements. Record retention. Access to records. All records required by this section shall be provided upon request to employees, former employees, representatives designated by the individual employee, and the Assistant Secretary. Transfer of records. Exemptions.
Additional Considerations
Signs are to be posted in areas where noise levels are above 85 dBA stating that hearing protection is required.
When noise levels are particularly high (say > 95 dBA) you should also check that the hearing protection that you are providing is adequate. These noise exposure limits are not based on instantaneous sound levels.
You may need assistance in determining whether your workplace has excessive noise or in setting up your workplace hearing conservation program. If so, Safety By Design is here to help. We can assist you in protecting your workers and complying with OSHA’s requirements.