Johnson Space Center Manual - After (example 3) (Before version)
Johnson Space Center Handbook Chapter--After
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."