osha hearing conservation program short
TRANSCRIPT
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10/1/99 Created By: C. Miterko 2
29 CFR 1910.95
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What is Sound? Sound is what we hear andis produced by vibratingobjects and reaches thelisteners ears as waves in theair or other media.
When an object vibrates itcauses slight changes in airpressure. These air pressurechanges travel as wavesthrough the air and producesound.
. .
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.
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What is Noise?
Hertz (Hz)
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Frequency
Humans can typically hearbetween 20 - 20,000 Hz 20
20000 3000 0.00002 Pa
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dB .
:dB = 20 log {sound pressure/Ref. Pressure (0.00002
Pa)}
Sound pressure level in very quite room where thesound pressure is 0.002 Pa is:
Lp (dB) = 20 log (0.002/0.00002) = 20 log 100 = 40 dB
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Common Sounds0 dB Threshold of Hearing
30 dB Soft Whisper
40 dB Quiet Office
60 dB Conversational Speech
80 dB Very noisy restaurant
90 dB Subway
110 dB Woodworking
120 dB Hydraulic press
140 dB Threshold of Pain
Jet plane
180 dB Rocket
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How do we Hear?
1- 2- -3 -4
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Example
In the field, we determined the loudness of
two compressors right next to each other
How loud is this area?
Do we add?Do we add and take the average?
89 dB 87 dB
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Neither, because it is a log scale
We use the following chart
82 dB + 83 dB = 86 dB
87 dB + 89 dB = 91 dB
Difference in dBValues
Add to HigherLevel
0-1 dB 3 dB
2-3 dB 2 dB
4-9 dB 1 dB
10 dB or more 0 dB
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How does the Safety Person
determine noise levelsSound level meter
Determine theloudness (dB) ofnoise at any given
moment
Personal Dosimeters
Worn by employees
Measures the average
loudness in an 8 hourwork shift
8hr. TWA (TimeWeighted Average)
8
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What does OSHA say?
At 85 dB (8hr. TWA) (Action level) (885 ) Train employees
Make hearing protection available
Sample for noise levels
Do hearing tests
Notify employees of results
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Hearing Conservation Program
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Hearing Conservation Program
Monitoring:
Employers should monitor noise exposure
levels to identify employees who are
exposed to noise levels at or above 85
dBA averaged over 8 working hours, or
an 8-hour time-weighted average (TWA).
Noise level meters & Noise Dosemeter are
used after being calibrated.
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When the daily noise exposure has two or morenoise exposures at different levels, their
combined values should be considered. (Use thefollowing formula)
F(e) = (T(1) divided by L(1) + (T(2) divided byL(2(( + )T)n( divided by L)n((
F(e)= The equivalent noise exposure factorT= The period of noise exposure at any essentially
constant level.
L= The duration of the permissible noise
exposure at the constant level.If the value of F(e) exceeds unity (the value 1), the
exposure exceeds PEL.
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Example:
110 dbA 0.25 hours
100 dbA 0.5 hours
90 dbA 1.5 Hours
F(e) = (0.25/0.5) +
(0.5/2)+(1.5/8)
F(e)=0.5+0.25+0.1888
F(e) = 0.938
Since F(e) does not exceed
unity (1), the exposure
limit is within
permissible limits
Duration Per
Day, Hours
Sound Level
dBA
8 90
6 92
4 95
3 97
2 100
1 102
1 105
107
110
115
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Audiometric Testing
Should the noise level monitoring determine
that employees are being subjected to levels
equaling or exceeding a TWA of 85 dBA, the
next step is to establish an audiometric testingprogram for those exposed at no cost to the
employee.
The important elements of an audiometric
program include: Baseline audiograms, Annualaudiograms, Control measures, Training, and
follow-up procedures.
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Baseline Audiograms
It is the reference audiogramagainst which future audiogramsare compared.
Must be provided within 6months of an employees firstexposure at or above 8-hour TWAof 85 dBA. (Control measuresshould be taken)
Baseline Audiogram must bepreceded by 14 hours withoutexposure to workplace noise.
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Annual Audiograms
After baseline audiogram has been taken,
each employee exposed to noise levels at
the 85 dBA or above shall have annual
examination.
Annual audiogram must be conducted
within 1 year of the baseline.
Compared with baseline audiograms
results.
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Continued
To determine whether an employee hasexperienced any recordable hearing loss.
The hearing loss is reffered to in the
OSHA standard as :Standard ThresholdShift (STS).
OSHA defines STS as a change in
hearing threshold relative to the baselineaudiogram of an average of 10 dB ormore at 2000, 3000, and 4000, Hz ineither ear.
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Example Baseline Audiogram
125 250 500 1K 2K 3K 4K 6K 8K
10
0
10
20
30
40
50
Baseline Audiogram
(The initial audiogram
taken by worker whenfirst employed.)
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Annual Audiogram (Showing STS)
125 250 500 1K 2K 3K 4K 6K 8K
10
0
10
20
30
40
50
BASELINE
ANNUAL
169
816 + 9 + 8 = 3333 / 3 = 11
Reportable Loss? NO
STS ? YES
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Control
The standard states that if the 90 dB PEL
is being exceeded, feasible
administrative or engineering controls
shall be utilized.
If fails, PPE shall be provided and used
to reduce sound levels.
Administrative Controls
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Administrative Controls
* Are defined as, Methods of controlling
employee exposures by job rotation,
work assignment, or time periods away
from the hazards.
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Engineering Control
Are defined as Methods of controlling
employee exposures by modifying the
source or reducing the quantity of
contaminants released into the workroomenvironment.
Example: installing noiseabsorbing
acoustical foam or baffles to capture anddeaden reverberating noise.
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Hearing Protectors
Hearing protectors shall be made
available and shall be worn by all
employees exposed to an 8-hour TWA of
85 dBA or greaters.
Types of hearing protectors:
Ear muffs
Ear plugs
Ear canal
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Earmuffs Earplugs Canal Caps
Examples of Hearing Protectors
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Hearing ProtectionNRR- Noise reduction rating
Express - 25 NRR
Classic - 29 NRR
Max Lite - 30 NRR
DO NOT Subtract the NRR from the
noise level
WRONG (109 dB - 25 NRR = 84 dB)
You must use the Safety Factor
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Safety Factor
OSHA says the hearing protection isdesigned to reduce the noise by theNRR, but that is unlikely to happendue to :
Leaks in the sealVibration
Improper insertion
(NRR - 7)
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Example of NRR Protection
The noise at a large compressor is
109 dB
You are wearing the Express plugs with
anNRR of 25
Do you have enough protection to placeyou below 90 dB level?
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Training - Recordkeeping
Employees training is very important. All
employees exposed to noise at a TWA of
85 dBA or greater shall participate in a
hearing conservation training program.
An accurate records shall maintained of
all employee exposure measurements.