Noise in the Workplace and Hearing Loss
Exposure to excessive noise over and extended period of time will result in hearing loss. There are also situations where hearing loss may occur very rapidly.
Protecting the hearing of employees is extremely
important. Although loss of hearing
through aging usually follows a normal
pattern, when we are exposed to excessive
noise, hearing loss can occur prematurely from excessive
exposure to noise in the workplace. Hearing loss
is a serious hazard that is often painless, progressive,
and permanent.
Loss of one’s hearing reduces the quality of life, and
being unable to hear warnings and other auditory signals
at work can create serious hazards.Additionally, excessive
noise levels have also been associated with digestive
problems, irritability, loss of concentration, and
even high blood pressure. All of these effects can create
their own adverse health effects and hazards, both at and
away from the workplace.
Noise sources are numerous.Manufacturing equipment,
motor vehicles, heavy construction equipment,
power tools, hand tools, aircraft noise, weapons, and
even lawn maintenance equipment, to name a few, are
some examples where occupational noise may be encountered.
It is quite common for people to be exposed
to unsafe noise levels that can result in hearing loss, and
exposure to excessive noise over an extended period of
time will result in hearing loss. There are also some situations
where hearing loss may occur very rapidly.
What Can Employers Do
to Prevent Hearing Loss?
This is a three-step process to prevent hearing loss in
the workplace: recognizing that a noise problem may
exist, evaluating the extent of the potential problem,
and controlling it.
Recognizing the problem may be as simple as spotting
the fact that a worker is unable to properly communicate
with another worker a few feet away. But the
complexity of the work site, varying exposure scenarios
of the employees, and many other situations usually
make identification of a noise problem more difficult.
Either way, the employer must be able to determine how
much noise is in the workplace in a quantifiable manner.
Measurements can be done using various soundmeasuring
devices, including sound level meters,
dosimeters, and octave band analyzers. A sound level
meter can be used to get an overview of the noise created
by each activity an employee performs or give an
overall noise level in a particular area. A noise dosimeter
continuously measures the sound levels to which an
employee is exposed throughout the day, using a microphone
that is positioned near the ear. It provides an
8-hour time weighted average (TWA). An octave band
analyzer, which is a more sophisticated device, may be
used when there are very predominant frequencies of
noise, but often it is not necessary to use such a device
unless an acoustics professional is trying to develop a
strategy to engineer the noise out.
Any of these measurements should be performed by
a qualified professional such as a Certified Industrial
Hygienist, Certified Safety Professional, or other qualified
health and safety professional.
The Occupational Health and Safety Administration
and code of accepted practice dictate that, wherever
feasible, controls be accomplished through engineering
methods and administrative controls before
the use of hearing protection devices. Examples of this
are engineering controls that include using quieter
manufacturing methods, properly maintaining
equipment, eliminating a noise source completely,
building enclosures, or the use of sound-damping
technology. When engineering controls cannot entirely
mitigate the noise exposures, the next step is to
use administrative controls.
Administrative controls may include automating
the process to remove or limit the time the employee
must work in a particular area, changing operating
schedules (such as using noisy equipment on shifts
when there are fewer employees), and rotating employees
out of noisy areas.
The last line of defense is the use of hearing protection
devices. When noise exposures are greater
than 90dBA as an 8-hour TWA and engineering and
administrative controls have not reduced the overall
exposure adequately, then hearing protective devices
are required. Additionally, when exposures exceed
85dBA as an 8-hour TWA, the employer must implement
a Comprehensive Hearing Conservation Program in accordance with 29 CFR 1910.95.
This includes defining when the program is
to be implemented and for which employees,
periodic noise monitoring, employee
notifications, allowing employees to observe
the noise monitoring, audiometric
testing, training, and recordkeeping.
Advantages and Disadvantages of Exposure Controls
There are advantages and disadvantages associated
with each line of defense. Engineering
controls can be expensive over the short
term, yet they may be the most economical
method of choice over the long term because,
once the problem is engineered out,
further investments will be minimal.
Administrative controls require very
formal procedures, must be comprehensive,
and require that management and employees
comply with the procedures implemented.
For instance, administrative
controls can be easily nullified if a production
schedule changes and must be run on
other shifts or an employee who normally
rotates into an area is not available to relieve
the other employee in the noisy area.
Finally, a Comprehensive Hearing Conservation
Program requires continuous investment
and time, which over a long term
can amount to considerable and recurring
expense. All costs associated with the hearing
conservation program are to be provided
at no cost to the employee, which requires
the employer to bear all the costs of
this program.
Assuming that not all the noise sources
can be engineered out or exposures reduced
through administrative controls, hearing
protection devices must be considered. The
types of equipment to offer the employee
must be determined by the employer;
OSHA requires that, when a Comprehensive
Hearing Conservation Program is implemented,
“Employees shall be given the
opportunity to select their hearing protectors
from a variety of suitable hearing protectors
provided by the employer.”
Choosing Hearing Protectors
Hearing protectors are an accepted method
of protecting employees’ hearing. Hearing
protection devices include ear plugs, ear
muffs, semi-aural bands, and electronic devices
that electronically block out noise.
Hearing protectors used in the workplace
must have a Noise Reduction Rating (NRR)
in accordance with testing set forth by the
Environmental Protection Agency.The NRR
is a rating assigned to each device that indicates
how much noise attenuation the person
might be expected to achieve under optimal
conditions. It is important to stress that
use of hearing protection devices is considered
a last resort.
Choosing the right hearing protector requires
careful consideration of several elements.
At sites where low-frequency noise
predominates, ear muffs can be very helpful.
Semi-aural bands or ear muffs are also useful
in situations where someone periodically
goes in and out of noisy environments and
needs to remove and put on the device many
times throughout the day.
Sites can be very dirty, and therefore employees
may want a product that is easy to
maintain or requires little or no maintenance.
Ear plugs are very useful in these
types of situations, although wearers must
be careful that their dirty hands do not contaminate
the devices.
Another very important factor is how the
hearing protector interacts with other personal
protective equipment, such as hard
hats, eye protection, and welding hoods. For
instance, eye protection may interfere with
the use of ear muffs.
Finally,one of the most important things
for a hearing conservation program to be
successful is to get employees to buy into the
program. This can be done with appropriate
training.When the employees understand
what the consequences of losing their hearing
can be, it is more likely they will comply
with the hearing conservation requirements.
There are excellent training tools available,
including videos that demonstrate how one’s
hearing works and the devastating effect of
loss of hearing. Not being able to hear your
friends and family, the television, the radio,
and the sounds of nature are losses that no
one should have to experience as a result of
not being protected from excessive noise in
their work environment.
This article originally appeared in the September 2008 issue of Occupational Health & Safety.