OhASIS HOME | Biosafety Information | Safety Manuals
CDC Office of Health and Safety
Hearing Conservation Program
SECTION ONE - INTRODUCTION 1.1 Policy
1.2 Program Organization
SECTION TWO - RESPONSIBILITIES 2.1Office of Health and Safety
2.1.1 Industrial Hygiene Section
2.1.2 Occupational Health Clinic
2.1.3 Training Activity
2.2 Supervisors
2.3 Employees
SECTION FIVE - MEDICAL SURVEILLANCE 5.1 Notification
5.2 Audiometric Testing
SECTION SIX - TRAINING SECTION SEVEN - PROGRAM EVALUATION SECTION EIGHT - STANDARD OPERATING PROCEDURES SECTION NINE - RECORDKEEPING REFERENCES
APPENDICES A. Noise - Training Information
B. OSHA Standard 29 CFR 1910.95, "Noise"SECTION ONE - INTRODUCTION
Evidence is well established that worker exposure to noise of sufficient intensity and duration can result in hearing damage. Noise-induced hearing loss rarely results from just one exposure; it can progress unnoticed over a period of years. Initial noise-induced hearing loss occurs at the higher frequencies where the consonant portion of speech is found, making communications difficult.
It is the policy of the Centers for Disease Control and Prevention (CDC) to provide employees with a safe and healthful working environment. This is accomplished by utilizing facilities and equipment that have all feasible safeguards incorporated into their design. When effective engineering controls are not feasible, or when they are being initiated, administrative controls will be used when and where possible followed by the use of personal protective equipment.
The primary goal of the CDC Hearing Conservation Program is to reduce, and eventually eliminate hearing loss due to workplace noise exposures. The program includes the following elements:
- Work environments will be surveyed to identify potentially hazardous noise levels and personnel at risk.
- Environments that contain or equipment that produces potentially hazardous noise should, wherever it is technologically and economically feasible, be modified to reduce the noise level to acceptable levels.
- Where engineering controls are not feasible, administrative controls and/or the use of hearing protective devices will be employed.
- Periodic hearing testing will be conducted to monitor the effectiveness of the hearing conservation program. Early detection of temporary threshold shifts will allow further protective action to be taken before permanent hearing loss occurs.
- Education is vital to the overall success of a hearing conservation program. An understanding by employees of the permanent nature of noise-induced hearing loss, CDC hearing conservation program, and the employee's responsibilities under the program are all essential for program effectiveness.
The CDC Office of Health and Safety (OHS), aware that excessive noise exposure is a potential cause of hearing loss, is establishing a hearing conservation program that is more conservative than that required by OSHA. The Office of Health and Safety has adopted the American Conference of Governmental Industrial Hygienists (ACGIH) noise exposure limits referred to as threshold limit values (TLV):
Duration per day, hours Sound level (dBA) 16 80 8 85 4 90 2 95 1 100 1/2 105 1/4 110 1/8 115 When the sound levels listed above are exceeded, feasible administrative or engineering controls will be instituted. If the controls fail to reduce the sound levels to within those listed above, hearing protection will be provided and used to reduce the sound levels to an acceptable level. In addition, OSHA requirements dictate that whenever employee noise exposures equal or exceed an 8-hour time-weighted average (TWA) of 85 dBA, slow response, a continuing effective hearing conservation program shall be instituted.
The CDC Hearing Conservation Program is organized and administered through an established Industrial Hygiene Procedure (IHP) and standard operating procedures (SOPs). The IHP outlines and defines program responsibilities and describes a minimum acceptable Hearing Conservation Program. The IHP was prepared by the Industrial Hygiene Section, Chemical and Physical Hazards Branch, OHS, and reviewed by the Office of Health and Safety. The IHP developed for the Hearing Conservation Program is incorporated in the OHS Industrial Hygiene Program Manual as IH-IHP-7.0 and is included as Appendix A of this document.
SECTION TWO - RESPONSIBILITIES
2.1 Office of Health and Safety
2.1.1 Industrial Hygiene Section, CPHB
The Industrial Hygiene Section is responsible for developing, implementing, and administering the CDC Hearing Conservation Program. Additional responsibilities include:
- Identification of work areas and equipment within CDC facilities where noise levels equal or exceed 80 dBA.
- Identification, through personnel monitoring, of CDC employees whose noise exposure level equals or exceeds an 8-hour TWA of 80 dBA. Notification of employee exposure measurements is sent to the Occupational Health Clinic to be included in employees' medical files.
- Annual remonitoring of identified at-risk employees.
- Resurvey of work areas and equipment where noise levels exceed 80 dBA every 2 years.
- Training of employees in the need for, proper use and care of hearing protection devices.
- Identification of noise control measures (including engineering and administrative controls) and recommendations.
2.1.2 Occupational Health Clinic
The Occupational Health Clinic (OHC) is responsible for conducting baseline and annual audiograms for new employees who may be assigned to tasks with potential exposure to elevated levels of noise. OHC also schedules and conducts audiograms on an annual basis for employees exposed to sound levels greater than or equal to 80 dBA. The OHC is responsible for notifying the Industrial Hygiene Section, CPHB, OHS, of all employees who have experienced significant changes in hearing (standard threshold shifts) in order that follow-up investigations may be conducted.
The Training Activity, OHS, is responsible for coordinating and scheduling health and safety training courses and seminars presented or sponsored by OHS for CDC personnel. The Training Activity also maintains documentation of the training courses presented in accordance with OHS program requirements.
It is the responsibility of Supervisors to ensure that all of their employees exposed to noise levels equal to or greater than 80 dBA have access to appropriate hearing protective devices in the work area. Supervisors are also responsible for enforcing the use of hearing protective devices and engineering and administrative controls in designated noise hazardous areas.
Employees are responsible for wearing and maintaining hearing protective devices as instructed. Employees exposed to excessive levels of noise must also participate in annual training programs and the medical surveillance program which includes audiometric testing.
SECTION THREE - NOISE EVALUATION AND SURVEILLANCE PROCEDURES
3.1 Identification of Hazardous Noise Areas
OHS will identify work areas within CDC facilities where noise levels equal or exceed 80 dBA. Records shall be maintained by OHS and updated at least every two years to determine if any alteration in noise levels has occurred. Those areas where the noise levels are below 80 dBA will not be routinely monitored. Identification of hazardous noise areas and equipment and any subsequent noise monitoring will be conducted by the Industrial Hygiene Section, CPHB, OHS.
Signs will be posted at the entrance to any work area where noise levels exceed 80 dBA, requiring anyone entering the area to wear proper hearing protection. Personnel who work in these areas shall have hearing protection supplied to them, shall be instructed in its proper use, and be required to wear this equipment when in these identified areas. It is the responsibility of the area supervisor to ensure that these precautions are maintained.
Equipment which produces noise levels greater than 80 dBA, or 120 dB peak sound pressure levels shall also be appropriately labeled.
3.2 Noise Measurements and Exposure Assessments
In order to effectively control noise it is necessary that the noise be accurately measured according to standard procedures and that the measurements be properly evaluated against accepted criteria. All noise monitoring will be conducted in accordance with established standard operating procedures.
The monitoring of employees for noise exposure is made up of two parts, area and personal monitoring. Area measurements are generally obtained first. If noise levels are at or above 80 dBA, personal monitoring using dosimeters is then performed. Sample data sheets will be used to record monitoring data for both area and personal noise monitoring results.
In an area survey, measurements of environmental noise levels are recorded using a sound level meter to identify work areas where employees' exposures may be above hazardous levels, and where more thorough exposure monitoring may be needed. Area monitoring is conducted using a calibrated sound level meter set to the A scale, slow response. Within the area of interest, several different locations will be measured. Typical measurement locations would include:
- In the hearing zone at the employee's normal work location.
- Next to the noise source(s).
- At the entrance(s) to the work area.
- At other locations within the area where the employee might spend time working.
A rough sketch of the area will be included with the results showing the locations where the noise readings were obtained.
If the noise levels are below 80 dBA on a time-weighted average basis in the area, no further routine monitoring will be required for that area. Should any of the noise measurements equal or exceed 80 dBA, records shall be maintained as to the noise levels recorded, where they were taken, and the source(s) of the noise. These records shall be updated at least once every two years to determine if any changes have occurred that would warrant remonitoring of exposed personnel. If any of the measurements equal or exceed a noise level of 80 dBA, employees who work in or near the high noise area or equipment shall have their noise exposure determined through personnel monitoring using dosimeters.
Determination of the noise exposure level will be accomplished using calibrated noise dosimeters. Each employee to be monitored will have a dosimeter placed on him/her at the beginning of his/her normal work shift with the microphone placed in the "hearing zone". The dosimeter will be worn for the full duration of the work shift while the employee performs his/her normal work routine. At the end of the work shift, the dosimeter will be removed and information printed out as soon as possible. Background information will be collected from each employee detailing job description, unusual job activities, etc., for the time period sampled. Those employees whose noise exposure equals or exceeds 80 dBA on an 8-hour TWA will be referred to the CDC Occupational Health Clinic for inclusion in the Hearing Conservation Medical Surveillance Program.
3.3 Remonitoring of Hazardous Noise Areas
All areas where noise levels equal or exceed 80 dBA shall be remonitored at least every two years. Employees who work for extended periods of time (>2 hours) in the high noise areas and where their 8-hour TWA equals or exceeds 80 dBA will be monitored every year to determine their personal noise exposure.
Whenever an employee exhibits a standard threshold shift, as determined by the OHC, the employee's work place shall be remonitored to identify and ameliorate the cause.
3.4 Remonitoring Due to Changes
Any area with noise levels that equal or exceed 80 dBA shall also be remonitored whenever a change in production process, equipment, or controls increase the noise exposure such that additional employees are exposed to noise levels at or above 80 dBA on a time-weighted average basis. Areas where the noise levels have dropped below 80 dBA due to alterations in equipment, controls or process changes shall be eliminated from the monitoring program.
SECTION FOUR - NOISE CONTROL METHODS
4.1 Engineering and Administrative Controls
The primary means of reducing or eliminating personnel exposure to hazardous noise is through the application of engineering controls. Engineering controls are defined as any modification or replacement of equipment, or related physical change at the noise source or along the transmission path that reduces the noise level at the employee's ear. Engineering controls such as mufflers on heavy equipment exhausts or on air release valves are required where possible.
Administrative controls are defined as changes in the work schedule or operations which reduce noise exposure. If engineering solutions cannot reduce the noise, administrative controls such as increasing the distance between the noise source and the worker or rotation of jobs between workers in the high noise area should be used if possible.
The use of engineering and administrative controls should reduce noise exposure to the point where the hazard to hearing is eliminated or at least more manageable.
4.2 Personal Protective Equipment
Hearing protective devices (ear plugs, muffs, etc.) shall be the permanent solution only when engineering or administrative controls are considered to be infeasible or cost prohibitive. Hearing protective devices are defined as any device that can be worn to reduce the level of sound entering the ear. Hearing protective devices shall be worn by all personnel when they must enter or work in an area where the operations generate noise levels of:
- Greater than 80 dBA sound levels, or
- 120 dB peak sound pressure level or greater
4.2.1 Types of Hearing Protective Devices Hearing protective devices include the following:
- Insert Type Earplugs
A device designed to provide an air-tight seal with the ear canal. There are three types of insert earplugs - premolded, formable, and custom earplugs.
- Premolded Earplugs
Premolded earplugs are pliable devices of fixed proportions. Two standard styles, single flange and triple flange, come in various sizes, and will fit most people. Personnel responsible for fitting and dispensing earplugs will train users on proper insertion, wear, and care. While premolded earplugs are reusable, they may deteriorate and should be replaced periodically.- Formable
Formable earplugs come in just one size. Some are made of material which, after being compressed and inserted, expands to form a seal in the ear canal. When properly inserted, they provide noise attenuation values that are similar to those from correctly fitted premolded earplugs. Individual units may procure approved formable earplugs. Supervisors must instruct users in the proper use of these earplugs as part of the annual education program. Each earplug must be held in place while it expands enough to remain firmly seated. A set of earplugs with a cord attached is available. These earplugs may be washed and therefore are reusable, but will have to be replaced after two or three weeks or when they no longer form an airtight seal when properly inserted.- Custom Molded Earplugs
A small percentage of the population cannot be fitted with standard premolded or formable earplugs. Custom earplugs can be made to fit the exact size and shape of the individual's ear canal. Individuals needing custom earplugs will be referred to an audiologist.- Earmuffs
Earmuffs are devices worn around the ear to reduce the level of noise that reaches the ear. Their effectiveness depends on an air tight seal between the cushion and the head.4.2.2 Selection of Hearing Protective Devices
Employees will be given the opportunity to select hearing protective devices from a variety of suitable ones provided by the Office of Health and Safety. In all cases the chosen hearing protectors shall have a Noise Reduction Ratio (NRR) high enough to reduce the noise at the ear drum to 80 dBA or lower.
4.2.3 Issuance of Hearing Protective Devices
The issuance of hearing protective devices is handled through both the CDC/ATSDR Occupational Health Clinic (OHC) and OHS. The OHC will issue and fit the initial hearing protective devices (foam inserts, disposables). Instruction on the proper use and care of earplugs and earmuffs will be provided whenever HPDs are dispensed. Personnel requiring earmuffs in addition to earplugs will be informed of this requirement and educated on the importance of using proper hearing protection. The OHS will dispense ear muffs when necessary and will maintain a supply of disposable earplugs.
4.2.4 Use of Hearing Protective Devices
- Always use and maintain HPDs as originally intended and in accordance with instructions provided.
- Earmuff performance may be degraded by anything that compromises the cushion-to-circumaural flesh seal. This includes other pieces of personal protective equipment such as eyewear, masks, faceshields, and helmets.
4.2.5 Maintenance of Hearing Protective Devices
- Reusable earplugs, such as the triple flange or formable devices should be washed in lukewarm water using hand soap, rinsed in clean water, and dried thoroughly before use. Wet or damp earplugs should not be placed in their containers. Cleaning should be done as needed.
- Earmuff cushions should be kept clean. The plastic or foam cushions may be cleaned in the same way as earplugs, but the inside of the muff should not get wet. When not n use, ear muffs should be placed in open air to allow moisture that may have been absorbed into the cups to evaporate.
4.2.6 Hearing Protection Performance Information
The maximum of sound attenuation one gets when wearing hearing protection devices is limited by human body and bone conduction mechanisms. Even though a particular device may provide outstanding values of noise attenuation the actual noise reductions may be less because of the noise surrounding the head and body bypasses the hearing protector and is transmitted through tissue and bone pathways to the inner ear.
The term "double hearing protection" is misleading. The attenuation provided from any combination earplug and earmuff is not equal to the sum of their individual attenuation values.
SECTION FIVE - MEDICAL SURVEILLANCE
5.1 Notification
Upon identification of employees whose 8-hour TWA equals or exceeds 80 dBA, OHS will recommend to the Occupational Health Clinic and the employee's Supervisor, in writing, of the need to enroll certain employee(s) in the Hearing Conservation Medical Surveillance Program. Information supplied to the OHC will include the employee(s) name, supervisor's name, telephone number, CIO, and the noise levels recorded in the employee's work area, including dosimetry data. It will be the responsibility of the Supervisor to enroll his/her employee in the Hearing Conservation Medical Surveillance Program.
In work locations where either through administrative or engineering controls, noise levels are found to have fallen such that the employee's 8-hour TWA is below 80 dBA, OHS shall notify the Clinic and the employee's Supervisor, by memo, that the employees working in that area are no longer required to be enrolled in the Hearing Conservation Program. The final decision as to an employee's enrollment status will be left with the Occupational Health Clinic Physician.
The results of area and personal remonitoring shall be forwarded to the Clinic upon completion of the noise surveys.
Any personnel experiencing difficulty in wearing assigned hearing protection (i.e., irritation of the canals, pain) will be advised to immediately report this to their supervisor and make arrangements to go to the Occupational Health Clinic for evaluation as soon as possible.
The Occupational Health Clinic has the responsibility for administering the Audiometric Testing Program portion of the CDC Hearing Conservation Program. The object of the audiometric testing program is to identify workers who are beginning to lose their hearing and to intervene before the hearing loss becomes worse. Audiometric testing will be provided to all employees with exposure to noise levels of 80 dBA or greater. Annual retesting will be performed for all personnel enrolled in the Hearing Conservation Medical Surveillance Program.
SECTION SIX - TRAINING
The training and education program will provide information about the adverse effects of noise and how to prevent noise-induced hearing loss. At a minimum, all training will cover the following topics:
- Noise-induced hearing loss;
- Recognizing hazardous noise;
- Symptoms of overexposure to hazardous noise;
- Hearing protection devices - advantages and limitations.
- Selection, fitting, use, and maintenance of HPDs.
- Explanation of noise measurement procedures.
- Hearing conservation program requirements.
Employees will also be provided with copies of the OSHA noise standard (29 CFR 1910.95) and other handouts describing the CDC Hearing Conservation Program. Information provided in Appendix C of this document may also be used.
CDC employees shall be encouraged to use hearing protective devices when they are exposed to hazardous noise during activities at home; e.g., from lawn mowers, chain saws, etc.
All personnel identified for inclusion in the hearing conservation program should receive a minimum of one hour of initial instruction in the requirements of the program. Ideally this will be done when hearing protection is dispensed.
Appropriate refresher training annually thereafter and will be provided by the immediate supervisor. Supervisors will be provided annual training by the Office of Health and Safety.
Supervisors must contact the OHS Training Activity (x2146) to schedule training for new personnel assigned to work in noisy environments and for retraining of current personnel.
SECTION SEVEN - PROGRAM EVALUATION
Periodic program evaluations will be conducted to assess compliance with federal and state regulations and CDC Program requirements. Both the monitoring and audiometric testing portions of the CDC Hearing Conservation Program will be reviewed annually to assure its quality and effectiveness.
An evaluation of the Program, including wearer acceptance, appraisal of protection afforded, and field audits of hearing protection use and recordkeeping will be conducted at least annually. Items to be considered include:
- Standard operating procesures
- Training records and course content for supervisors and employees.
- Maintenance of HPDs
- Field audits of HPD use
- Review of recorded threshold shifts on OSHA log.
The findings of the CDC Hearing Conservation Program evaluation will be documented, and this documentation will list plans to correct faults in the program and set target dates for the implementation of the plans.
SECTION EIGHT - STANDARD OPERATING PROCEDURES
An important element of the CDC Hearing Conservation Program is the development of detailed standard operating procedures (SOPs). The SOPs outline the steps necessary to meet the goals of the Industrial Hygiene Procedure (Appendix A) and document Hearing Conservation Program activities within the Office of Health and Safety. The SOPs are periodically reviewed and revised by the Chief, Industrial Hygiene Section, CPHB, OHS, and the Office of Health and Safety.
The following SOPs have been developed and are maintained by the Industrial Hygiene Section:
- Basic Sound Survey Using a Sound Level Meter, IHP-SOP-7.1.
- Detailed Sound Survey Using a Noise Dosimeter, IHP-SOP-7.2.
- Hearing Conservation Program Training, IHP-SOP-7.3.
- Audit of the Healring Conservation Program, IHP-SOP-7.5.
The SOPs may be found in the OHS Industrial Hygiene Procedures Manual.
SECTION NINE - RECORDKEEPING
CDC Hearing Conservation Program records will include the following:
Record Location Medical Evaluation and Audiograms Office of Health and Safety
Occupational Health Clinic
Building 4, Room 121Training Records Office of Health and Safety
Training Activity
Building 14, SBHearing Conservation Program Manual, IHP, and SOPs Office of Health and Safety Industrial Hygiene Section Building 14, B-4 Hazard Evaluations (Work area noise surveys, personnel monitoring) Office of Health and Safety
Industrial Hygiene Section
Building 14, B-4Program Evaluations Office of Health and Safety
Industrial Hygiene Section
Building 14, B-4All non-medical records (ex., work area and equipment surveys) will be maintained for a period of five years. Results of hearing tests and medical evaluations performed for hearing conservation purposes as well as noise exposure documentation shall be recorded and shall be a permanent part of an employee's health record.
All personnel who routinely work in designated hazardous noise areas shall be identified and a current roster of such personnel shall be maintained and by the Industrial Hygiene Section, CPHB, OHS, and updated periodically.
REFERENCES
ACGIH, Threshold Limit Values and Biological Exposure Indices, Physical Agents, Noise, current edition
Berger, E. H., et.al., Ed., Noise & Hearing Conservation Manual, 4th ed., Akron, OH: American Industrial Hygiene Association, 1986.
NIOSH, A Practical Guide to Effective Hearing Conservation Programs in the Workplace, September 1990.
OSHA, General Industry Standard, 29 CFR 1910.95, "Occupational Noise Exposure"
Appendix A
Noise - Training Information
NOISE
Supervisors and exposed workers must become aware of and understand about the adverse effects of noise and how to prevent noise-induced hearing loss. People exposed to hazardous noise must take positive action, if progressive permanent hearing loss is to be prevented. Each exposed worker and supervisor should know the following.
- Noise exposure may result in permanent damage to the auditory system and there is no medical or surgical treatment for this type of hearing loss. Though the use of a hearing aid may provide some benefit, normal hearing will not be restored. Many people don't realize loud sounds can cause hearing loss. Furthermore, in its initial stages, the person may not notice a problem since noise-induced hearing loss is invisible, painless, and occurs in the high frequencies. It is dangerous to ignore the temporary characteristics of noise-induced hearing loss (such as ringing or buzzing in the ears, excessive fatigue, etc.).
- Each person should know how to recognize hazardous noise even if a noise survey has not been conducted an/or warning signs posted. Recognizing and understanding the adverse effects of off-duty noise exposures is also important. The best rule to follow is: "If you have to shout at arms length (approximately three feet) to talk face-to-face, you are probably being exposed to hazardous levels of noise."
- Preventing noise-induced hearing loss is accomplished by reducing both the time and intensity of exposure. Reducing exposure time is accomplished by avoiding any unnecessary exposure to loud sound. Reducing intensity is usually accomplished by wearing personal hearing protection. Each person must be able to properly wear and care for the particular type of hearing protection selected. Speech communication is difficult in high intensity noise. However, most people don't realize it's easier to understand speech if hearing protection is worn in a hazardous noise environment. Hearing protection reduces the noise and the level of speech, resulting in a more favorable listening level. hearing protection reduces the intensity of frequencies above the speech range; thus, reducing the noise and accentuating speech. People who claim wearing hearing protection makes it difficult to hear speech are probably in noise levels less than 85 dBA or have already developed a hearing loss.
- Each person must know how to tell if they have been overexposed to loud sound. Overexposure may occur even while wearing hearing protection. Earplugs and/or earmuffs alone may not be enough protection. Each time a temporary threshold shift (TSS) occurs, a certain degree of permanent loss results. The recognizable symptoms of overexposure are described as "dullness in hearing or ringing in the ears."
Appendix B
Occupational Safety and Health Administration Standard - 29 CFR 1910.95 - Noise
Health and Safety Manual Contents
Office of Health and Safety, Centers for Disease Control and Prevention,
1600 Clifton Road N.E., Mail Stop F05 Atlanta, Georgia 30333, USA
Last Modified: 1/2/97
Send us your Comments.