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Johnson Space Center Manual Example 3

Johnson Space Center Handbook Chapter


301.1 Purpose and Scope

The purpose of this chapter is to describe the minimum requirements for the hearing conservation program of JSC. These requirements apply to all operations on site at JSC, Sonny Carter Training Facility, and Ellington Field, and to any other operations directed by JSC.

301.2 Noise Exposure Limits

The permissible exposure limits for continuous noise are listed in table 301-1. It is desirable to keep exposure at or below the action level whenever possible.

Exposure to impact or impulse noise shall not exceed the limits listed in table 301-2. No exposures in excess of 140 decibels (dB) peak sound pressure level are permitted.

Table 301-1. Permissible Exposure Limits for Continuous Noise
Duration (Hours) dBA__
__ 16 80 8 85 4 90 2 95 1 100 0.5 105 0.25 110 0.125 or less 115

Sound level in decibels measured on the A-scale of a standard sound level meter set at “slow response”

Table 301-2. Permissible Exposure Limits for Impact or Impulsive Noise

Sound Level (dBP)__

__ Permitted Number of Impacts or Impulses per Day 140 100 130 1000 120 10000

Decibels peak sound pressure level.

301.3 Engineering Controls

Where feasible, facilities and equipment will be procured, designed, operated, and/or modified in such a manner as to prevent employee exposure to continuous noise levels above 85 dB measured on the “A” weighted scale (time-weighted average [TWA]) or impulsive noise above 140 dB. Any reduction in employee noise exposure, even if it is not reduced below 85 dBA, is beneficial. If engineering controls fail to reduce sound levels to within the limits of tables 301-1 and 301-2, hearing protective equipment and/or administrative methods of noise exposure protection must be used.

301.4 Personal Hearing Protection

Observe the following requirements:

a. Personal protective equipment is to be used only temporarily or where engineering controls are not feasible or practical.

b. Earmuffs and/or plugs shall be provided to employees assigned to work in areas where they will be exposed to continuous noise (without regard to duration of exposure) in excess of 85 dBA and to impulse noise in excess of 140 dB. Disposable earplugs shall be available for employee use where noise exposures are less than 85 dBA (for protection against nuisance noise), if they so desire. Earplugs shall be for the exclusive use of each employee and shall not be traded or shared. Use of ear protectors shall be mandatory and their use enforced by supervisors.

c. Earmuffs and/or ear plug use is mandatory for workers who work directly with machines or processes which produce noise levels at or above 100 dBA. Such protection is also mandatory for all workers in areas at or above 85 dBA where it has been determined that any work groups TWA noise exposures in that area are at or above 85 dBA.

d. Hearing protectors must attenuate employee noise exposure to a level of 85 dBA or below. A combination of both ear muffs and plugs are required where noise levels equal or exceed 110 dBA. For those with standard threshold shift (STS), protectors must attenuate exposure to an 8-hour TWA of 80 dBA. Estimation of the adequacy of hearing protector attenuation should be performed according to Occupational Safety and Health Administration (OSHA)-specified methods (29 CFR 1910.95, Appendix B).

e. The adequacy of hearing protector attenuation shall be reevaluated whenever employee noise exposures increase to the extent that the hearing protector currently in use may no longer provide adequate attenuation. More effective hearing protectors shall be provided when necessary.

f. Where reusable, preformed earplugs are used, they will be permanently issued to the employee and fitted to the individual under medical supervision. During fitting, the employee will be instructed in the proper method of insertion, storage, and cleaning of the earplugs. Earplugs will be checked during annual medical examinations.

g. Earmuffs will be provided for employees when analysis of noise environments shows that the attenuation provided by earplugs is not sufficient to reduce noise exposures below 85 dBA.

Earmuffs will be inspected by the user on a regular basis.

h. Special hearing protective equipment, such as sound-suppression communication headsets, may be used in noise hazard areas. These devices should be regularly inspected. Sound-suppression headsets which have been damaged, altered, or modified in any way that affects the attenuation characteristics may not be used. Where replacement parts, such as earcup seals, are available, the headsets may be repaired and reused. Where sound suppression headsets are not permanently

issued to individuals, such equipment must be cleaned and sanitized before being reissued.

301.5 Administrative Control

Where hearing protective equipment or engineering controls are not sufficient to attenuate noise to less than 85 dBA, the duration of time spent in the noise hazard area will be limited so as not to exceed the exposure limits in tables 301-1 and 301-2.

301.6 Noise Monitoring

301.6.1 Need for Monitoring

Measurement of potentially hazardous sound levels will be conducted when any information, observation, or calculation shows that an employee could be exposed to a noise level in excess of 80 dBA TWA. This includes, but is not limited to, times where there is a need to document representative noise exposures, where employees complain of excessive noise, or where it is difficult to understand a normal conversation when the speaker and listener face each other at a distance of two feet. Any new equipment, operation, job or procedure with the potential for creating hazardous noise should be evaluated with regard to noise emissions before start-up.

301.6.2 Observance of Monitoring

Employees and/or their representatives will be provided an opportunity to observe noise dosimetry and area monitoring activities.

301.6.3 Notification

Areas determined to have noise levels at or above 85 dBA must be posted as noise hazard areas.

Affected employees will be notified of the results of noise monitoring when the employee’s noise exposure meets or exceeds the action level so that they can be included in the medical monitoring program.

301.7 Medical Monitoring Program

301.7.1 Program Participation

a. Whenever an employee is routinely occupationally exposed (30 or more days per year) to continuous noise at or above the action level or to impact or impulsive noise in excess of the limits listed in table 301-2, the employee will be enrolled in a medical monitoring program. For the purposes of program enrollment, employee noise exposure shall be determined without regard to any sound attenuation provided by the use of hearing protectors.

b. Each employee placed in a job requiring participation in the medical monitoring program shall undergo a physical examination before assignment of duties involving exposure to high intensity noise. The examination will include a baseline audiogram, a medical examination to determine any pre-existing medical pathology of the ear, and a work history to document past noise exposures.

c. When a physical examination cannot be obtained before placement in a job requiring participation in the medical monitoring program, or when it is discovered that those already assigned to hazardous noise have not had a physical examination, one shall be conducted within 30 days thereafter. The audiogram must be preceded by a period of at least 14 hours during which there is no known exposure to sound levels in excess of 80 dBA. This time interval should be sufficient to allow recovery from noise-induced temporary threshold shift.

d. Personnel suffering from acute diseases of the ear should not be placed in hazardous noise areas until the condition has abated, particularly if such diseases preclude the wearing of hearing

protectors, cause hearing impairment, or produce tinnitus.

e. All employees who are enrolled in the medical monitoring program specified in Section 301.7.1.a will receive an annual audiogram.

f. All employees who have participated in the medical monitoring program will receive a final audiometric examination before termination of employment with NASA, job changes within the installation which would alter noise exposure, transfer to another installation, or retirement.

301.7.2 Recordkeeping

Recordkeeping shall be maintained in accordance with the OSHA standard for occupational noise exposure, 29 CFR 1910.95 (m).

301.8 Noise Hazard Warning Signs

Caution signs which clearly indicate the hazardous high noise levels and state the requirements to wear hearing protection will be posted at the entrance(s) to, or the periphery of, noise hazard areas. Decals or placards with similar statements will be affixed to power tools and machines which produce hazardous noise levels. Signs and decals shall have wording in black letters on a yellow or orange background.

301.9 Employee Training

Each employee who participates in the hearing conservation program will receive annual training. The training must include, as a minimum, an overview of the NASA Hearing Conservation Standard; a review of the effects of noise on hearing (including permanent hearing loss); noise control principles; the purpose of hearing protectors; the advantages, disadvantages, and attenuation characteristics of various types of ear protectors; instructions on selection, fitting, use, and care of hearing protectors; an explanation of the audiometric testing procedure; and the purpose of audiometric testing.

An education program shall be provided for supervisory and managerial personnel of hazardous noise areas, and their responsibility to comply with the Hearing Conversation Standard will be emphasized.

Personnel shall be encouraged to use hearing protectors whenever they are exposed to hazardous noise during off-duty activities (e.g. lawn mowers, firearms, etc.).


This could be you . . .

A worker didn’t wear hearing protection while in a high noise area. He later noticed ringing in his ears and experienced a temporary hearing threshold shift. This reduced his hearing capability for several days.

1. Who must follow this chapter?

You must follow this chapter if you work in an area that is continuously noisy like a mechanical room or has periodic loud noises like the flight line at Ellington Field.

2. What does this chapter cover?

This chapter covers the minimum requirements for JSC’s hearing conservation program. It covers how to know if your work area is too noisy and how to protect yourself from hearing loss.

3. What is “too noisy”?

The NASA action level for noise is noise levels greater than or equal to 80 dBA (time-weighted average (TWA)). There are two kinds of noises that are harmful: the continuous noise that you are exposed to continuously and the impact or loud noise you are exposed to periodically.

1. For continuous noise, a work area is considered too noisy if measured noise levels exceed the limits in this table. Usually, the area is too noisy if you have trouble understanding a normal conversation with someone 2 feet away from you.

Duration in hours . . ._ _** ** Decibel limit . . .____
__ ——————————- ———————————– 16 80 8 85 4 90 2 95 1 100 0.5 105 0.25 110 0.125 or less 115

Sound level in decibels measured on the A-scale of a standard sound level meter set at “slow response”

1. For impact noise, “too noisy” is anything that exceeds the limits in this table.

Sound level__**

__ Number of impacts or impulses allowed per day__**
140 100
130 1000
120 10000

Decibel peak sound pressure level

1. Under no circumstances are you to be exposed to noise exceeding 140 decibels without protective equipment.

4. What noise hazard warning signs must be posted?

If the noise level equals or exceeds 85 dBA, you must:

1. Make sure caution signs are posted at the entrance or around the edge of the area that:

Clearly indicate that the area is a high noise area.

State that hearing protection is required (where the TWA exceeds 85 dBA).

Are yellow or orange with black letters.

2. Put warning decals on power tools and machines with hazardous noise levels.

5. How do I know if my work area is too noisy?

The easiest way to know if your work area is too noisy is to check for warning signs posted just outside the hazard areas or on power tools or machines with hazardous noise levels. If your work area, tool, or machine is new or you think your work area is too noisy, call Environmental Health Services at 483-6726 to get an evaluation.

Environmental Health Services will monitor the situation and report back to you in writing with their findings and recommendations. If your work area is too noisy, you will be notified that you may be included in the hearing conservation medical monitoring program (see Paragraph 6 of this chapter).

6. What special precautions must I observe when working in a noisy area?

If you work in a noisy area, you must observe these precautions:

1. Use personal protective equipment when exposed to hazardous noise levels.

2. Use earmuffs or plugs if you are exposed to continuous noise that equals or exceeds 85 dBA for an 8-hour TWA or impulse noise that equals or exceeds 100 dB. Using hearing protectors is a mandatory part of your job and your supervisor will enforce it. For nuisance noise areas less than 85 dBA (TWA), your supervisor or company should make earplugs or earmuffs available.

3. Never trade or share earplugs. They are for your use only.

4. Environmental Health Services will tell you what kind of hearing protection to wear in your noisy area.

5. Have your noisy area re-evaluated by Environmental Health Services whenever the noise level increases to see if your current protection is still adequate.

6. Reusable earplugs must be permanently issued to you and fitted to you under medical supervision. During fitting, you will be instructed in the proper method of insertion, storage, and cleaning of the earplugs. Your earplugs will be checked during your annual medical examination.

7. You will be provided both earmuffs and earplugs when analysis shows that the protection provided by earplugs doesn’t reduce noise exposures below 85 dBA (TWA).

8. Inspect your earmuffs on a regular basis. Don’t use them if they have been damaged, altered, or modified.

7. How do I know if I have hearing damage?

Whenever you are exposed to noise levels that exceed the NASA action level of 80 dBA (TWA) (see Paragraph 3 of this chapter) for more than 30 days per year, you will have an annual medical examination that includes an audiogram. The baseline medical examination includes:

1. An audiogram.

2. A medical examination to determine any pre-existing ear problems.

3. A work history to document past noise exposures.

When you leave the job in the noisy area, you will have an exit audiogram.

8. What training must I have to work in a noisy area?

If you are exposed to noise at or exceeding the NASA action level of 80 dBA (TWA) for more than 30 days per year, you will be put into the JSC hearing conservation program. Your training must cover:

1. Elements of JSC’s hearing conservation program.

2. Effects of noise on hearing.

3. Noise control practices including hearing protection at home.

4. Purpose, types, and maintenance of hearing protectors.

5. Explanation of audiometric testing purpose and procedures.

If you are a supervisor, you must take training so that you are familiar with the hazards of noise, the controls to be used in your area, and your responsibilities.

9. What other requirements must I follow when I work in a noisy area?

You must also follow:

1. NHS/IH 1845.4, “NASA Health Standard for Hearing Conservation.”

2. 29 CFR 1910.95, “Hearing Conservation.”