Section III: How do I evaluate noise exposure?
| |
The first step toward solving any noise problem is to define it. To understand what requirements must be implemented
according to OSHA's noise standard [1910.95,
it is necessary to determine exposure levels. The following sections provide information about evaluating noise exposure levels:
|
Checking for noise source |
|
Indications of a Problem |
There are various factors that may indicate noise is a problem in the workplace. While people react differently to
noise, subjective responses should not be ignored because they may provide warnings that noise may be at unacceptable levels.
- Noisy conditions can make normal conversation difficult.
- When noise levels are above 80 decibels (dB), people have to speak very loudly.
- When noise levels are between 85 and 90 dB, people have to shout.
- When noise levels are greater than 95 dB, people have to move close together to hear each other at all.
- High noise levels can cause adverse reactions or behaviors. See more information about effects on communication and performance (App I:C).
|
|
Walkaround Survey |
A walkaround survey should be performed to screen for noise exposures and to determine if additional monitoring is
necessary. When screening for noise exposures, sound level meter measurements and estimates of the duration of exposure are
sufficient. The resulting spot readings can be used to determine the need for a more complete evaluation. The following general approach may
be followed:
- Tour the facility and develop a detailed understanding of facility operations and potential noise sources. Take the tour with someone
who is familiar with plant operations. Speak with knowledgeable personnel about operations and maintenance requirements. Make notes on a
diagram of the floor plan if possible. Look for indications that noise may be a problem.
- Use a sound level meter (App III:A) to take spot readings of
operations that are in question. It may be useful to mark the sound levels on a diagram of the floor plan. Make notes regarding what
equipment is on or off.
- Estimate exposures by identifying workers and their locations and estimate the length of time they spend in different areas or how long
they operate particular equipment or tools.
If the results of the walkaround survey indicate time-weighted average (TWA) exposures of 80 dBA or
more, then additional noise monitoring should be performed. Remember to take into account the accuracy of the sound level meter when
making this estimation. For example, a Type 2 sound level meter has an accuracy of ±2 dBA. |
|
Workshift Sampling |
When the results of the walkaround survey indicate that noise levels may exceed those outlined in OSHA's noise standard
1910.95,
additional monitoring is necessary.
- Establish a sampling protocol for your workplace. A general protocol
(App III:B) is provided as an example.
- In addition to the general information collected during all health inspections, OSHA may collect certain information where it is
pertinent to evaluate compliance with OSHA standards
(1910.95,
1926.52, or
1926.101).
Additional information (App III:C) on inspection data is
also available.
- Sample the noise exposures of representative employees from each job classification that may be potentially overexposed.
- Use a dosimeter with a threshold of 80 dBA (A-weighted sound pressure level) and 90 dBA to measure noise exposures. Most modern
dosimeters use simultaneous 80 and 90 dBA thresholds and may be used accordingly.
Additional information (App III:A) on dosimeters is
also available.
- A dosimeter with a threshold of 80 dBA is used to measure the noise dose of those employees identified during the walkaround survey as
having noise exposures that are in compliance with Table G-16
of OSHA's noise standard 1910.95,
but whose exposure may exceed the levels specified in Table G-16a [1910.95 Appenix A: Noise Expsoure Computation].
In other words, the 80-dBA threshold is used to determine compliance with the 85 dBA time-weighted average (TWA) action level under OSHA's
noise standard.
- The dosimeter with a threshold of 90 dBA is used to measure the noise dose of those employees identified during the walkaround survey as
having potential noise exposures that exceed the sound levels in Table G-16
[1910.95] or Table D-2
[1926.52].
In other words, the 90 dBA threshold is used to determine compliance with the permissible exposure limit (PEL).
- As a minimum, sampling should be conducted for a length of time necessary to establish whether exposures are above the limits permitted by
Table G-16,
Table G-16a, or
Table D-2
(for general industry or construction workplaces, respectively). Instrument accuracy must be taken into account.
- Consider the following with respect to the monitoring results:
- TWA exposures at or above the action level of 85 dBA require a hearing conservation program
[1910.95 (c-n)]
(results obtained from the 80 dBA threshold).
- TWA exposures exceeding the PEL (Table G-16)
require feasible engineering or administrative controls to be implemented [1910.95(b)]
(results obtained from the 90 dBA threshold). Refer to the OSHA Field Inspection Reference Manual (FIRM)
for additional information.
- There is also information specific to evaluating noise exposure of employees wearing sound-generating headsets (App III:D).
|
|
Back to Top
www.osha.gov
