Noise Mapping-May 2017

Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety

May 2017

IN THIS ISSUE: Noise Mapping

According to OSHA, each year 22 million U.S. workers are exposed to potentially damaging noise levels on the job. A noise map can be an important first step in determining whether workers at your facility are among that number.
When evaluating noise exposure, creating a noise map is a preliminary step that can be helpful in determining which workers have noise exposure and what are the noisy processes and machinery.  A sound level meter is used to determine the noise level adjacent to the noisy equipment or process and/or at various distances from the noise source. These numbers, in decibels (dBA), are plotted on a facility map or on individual maps for each area. They can be compared with the OSHA Action Level of 85 dBA, the Permissible Exposure Limit (PEL) of 90 dBA, or other applicable standards.Where noise levels exceed one of these standards, an octave band analyzer can be helpful in determining the cause of the noise on a specific machine. It is a special sound level meter that divides noise into its frequency components. This information can aid in pinpointing the cause of the sound (e.g., slipping belt, bad bearings, and vibrating supports) and help in identifying control measures. The machine can be rechecked with a sound level meter once changes are made to confirm the extent to which the noise reduction measures have reduced noise levels. The noise map should be updated to reflect these changes.


If noise levels documented on the noise map continue to be at or above the Action Level, employees who work in those areas will require further testing. Sound Level meter readings are instantaneous and may not reflect employee exposures as they move closer and further from the noise sources during their shifts. This follow-up monitoring should focus on noise dosimetry. An industrial hygienist or qualified safety professional usually conducts this testing. The employee wears a noise dosimeter during his/her shift. It contains a microphone that is placed near the ear and averages the employee’s noise exposure over time. Since occupational noise standards are specific to worker exposures, dosimetry gives the best approximation of their actual exposures.

For more information on this topic and to discuss your company’s safety and industrial hygiene needs call OccuSafe at (214) 662-6005 or visit us at

OccuSafe Industrial Hygiene & Safety, Inc. provides skills and expertise to recognize, evaluate and control hazards and injuries in the areas of industrial hygiene, occupational safety and health. OccuSafe services companies of all sizes in a range of industries.

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