The American Academy of Audiology estimates there are upwards of 5 million, perhaps as many as 30 million Americans occupationally exposed to noise levels greater than the OSHA Action Level of 85 dBA. Additionally, they estimate that one in four of these workers will develop a permanent hearing loss as a result of trying to earn a living.
It should be easy to recognize that the need for occupational hearing loss prevention extends well beyond the obvious practical desire to preserve hearing. The economic impact of hearing loss is intertwined with a healthy, safe workplace. In order to know whether or not your employees are exposed to elevated noise levels it may be necessary to perform noise monitoring of your facility.
What is the Purpose of Noise Dosimetry?
OSHA requires that employees be placed in a hearing conservation program if they are exposed to average noise levels of 85dB or greater during an 8 hour workday, which is the OSHA Action Level for noise. If you have a noisy work environment you should determine if exposures are at or above this level; it may be necessary to measure the actual noise levels in the workplace if you have to raise your voice or yell to be heard at a distance of three to five feet. The monitoring usually starts with sound mapping your facility as a screening tool, and then focuses in on problem areas with more intensive personal noise dosimetry monitoring.
When is it necessary to implement a noise monitoring program?
Remember it is not necessary for every employer to measure workplace noise. Noise monitoring or measuring must be conducted only when exposures are at or above 85dB. Other factors which suggest that noise exposures in your facility may be above the Action Level include employee complaints about the loudness of noise, indications that employees are losing their hearing, or noisy conditions which make normal conversation difficult. As an employer you should also consider any information available regarding noise emitted from specific machines or operations.
How is noise measured?
Basically, there are two types of instruments to measure noise exposures: a sound level meter and a noise dosimeter. A sound level meter measures the intensity of sound at a given moment. Since sound level meters provide a measure of sound intensity at only one point in time, it is generally necessary to take a number of measurements at different times during the day to estimate noise exposure over a workday. Sound level meters are great tools to use for sound mapping your facility.
The sound mapping process includes drawing "maps" of the sound levels within different areas of your facility. By using sound level mapping and information on employee locations throughout the day, it is possible to estimate individual exposure levels.
A noise dosimeter is very similar to a sound level meter except that it stores sound level measurements and logs these measurements over time. This approach provides an average noise exposure reading for a given period of time, such as an 8-hour workday. Since the noise dosimeter is very portable and can be worn by employees; it is used to measure noise levels in which the employee travels throughout their work shift. This process is typically referred to as "personal" noise monitoring.
Key Points:
- Area monitoring can be used to estimate noise exposure when the noise levels are relatively constant and employees are not mobile.
- In workplaces where employees move about in different areas or where the noise intensity tends to fluctuate over time, noise exposure is generally more accurately estimated by the personal monitoring approach.
How often is it necessary to monitor noise levels?
Noise levels should be measured whenever there are significant changes in machinery or production processes that may result in increased noise levels; remonitoring should also be conducted to determine whether additional employees need to be included in the hearing conservation program.
Most environmental, health and safety (EHS) professionals will also recommend that employers remonitor periodically as part of a overall safety program (at least once every year or two) to ensure that all exposed employees are included in hearing conservation programs. Remember there are many different reasons to monitor for noise beyond OSHA requirements, such as worker’s compensation and legal tort. In Missouri for example worker’s compensation isn’t the sole remedy for workplace illnesses, which can include hearing loss from exposure to elevated noise overtime.
Additional Resources.
The Centers for Disease Control and Prevention publishes a Practical Guide for Preventing Occupational Hearing Loss which illustrates specific steps that can be taken to reduce the risk to your employees.
OSHA has published their requirements for General industry under 29 CFR 1910.95.
Of course if you still have questions contact us, we may be able to help.