Page 19 - Occupational Health & Safety, March 2019

■ Appropriate hearing protection (employees who have not had a Standard Threshold Shift, or STS, are not required to wear hearing protection);
■ A written Hearing Conservation Program; and
■ Audiometric testing.
It should be understood that OSHA uti- lizes an exchange rate of 5 dBA, which means that every 5 dBA the noise increases, the intensity of the noise doubles.
At the Permissible Exposure Limit (PEL) of 90 dbA, eight-hour TWA, 100 percent of the population will start to expe- rience hearing loss. When an employee is exposed at or above the PEL, the employer is required to:
■ Provide appropriate hearing protec- tion at no cost to employees;
■ Issue appropriately rated hearing protection to reduce exposure to below 85dBA, and employees are required to use it;
■ Through engineering and adminis- trative controls, employers must attempt to reduce noise exposures to below the PEL;
■ Have a written Hearing Conserva- tion Program; and
■ Conduct audiometric testing.
A Ceiling Limit (CL) of 115 dBA has been established. No employee shall be exposed in excess of 115 dBA of sustained noise for more than 15 minutes over a 24- hour period. Lastly, 140 dBA is the maxi- mum instantaneous level for impact noise not lasting longer than one second in du- ration. Table 2 shows examples of different decibel “A” levels.
Assessing Noise
Understanding what the rules are is only half of the battle with noise. The other half is assessing noise levels. This can be done in a multitude of ways, however, for the best results, I always recommend consulting
with a certified industrial hygienist (CIH) or other noise professional (e.g., a sound engineer) who is competent in noise evalu- ation. (As a side note for those interested, there are continuing education opportu- nities and publications available from the American Industrial Hygiene Association and the Council for Accreditation of Oc- cupational Hearing Conservation about industrial noise exposure and monitoring. I highly encourage interested professionals to take a look into professional develop- ment programs and publications.)
To assess noise, you will need three ba- sic items:
1. A personal noise dosimeter
2. A field calibration tool
3. A Type 2 sound level meter
These items can range from about
$1,000 to over $12,000, depending on man- ufacturers, vendors, and end user specifica- tions, such as intrinsically safe options. A few settings to remember when setting up a field noise instrument under the OSHA settings are:
1. OSHA uses a 5dBA exchange rate.
2. Frequency rating (weighting) should be on the “A” scale.
3. Meter response should be set to “Slow.” 4. Criterion level should be set at 80 dBA.
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