author: alajlan, abdulaziz m worker exposure to noise during paper mill: measurement ... ·...

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Author: Alajlan, Abdulaziz M

Title: Worker Exposure to Noise During Paper Mill: Measurement and Control.

The accompanying research report is submitted to the University of Wisconsin-Stout, Graduate School in partial

completion of the requirements for the

Graduate Degree/ Major: MS Risk Control

Research Advisor: Bryan Beamer, Ph.D.

Submission Term/Year: Summer, 2013

Number of Pages: 41

Style Manual Used: American Psychological Association, 6th

edition

I understand that this research report must be officially approved by the Graduate School and

that an electronic copy of the approved version will be made available through the University

Library website

I attest that the research report is my original work (that any copyrightable materials have been

used with the permission of the original authors), and as such, it is automatically protected by the

laws, rules, and regulations of the U.S. Copyright Office.

My research advisor has approved the content and quality of this paper.

STUDENT:

NAME Abdulaziz Alajlan DATE: 07/15/2013

ADVISOR: (Committee Chair if MS Plan A or EdS Thesis or Field Project/Problem):

NAME Bryan Beamer DATE: 7/15/2013

--------------------------------------------------------------------------------------------------------------------------------- This section to be completed by the Graduate School This final research report has been approved by the Graduate School.

Director, Office of Graduate Studies: DATE:

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Alajlan, Abdulaziz M. Worker Exposure to Noise During Paper Mill: Measurement and

Control.

Abstract

The purpose of this study was to identify and evaluate the noise exposures at Company

XYZ and to provide recommendations to reduce or eliminate the noise exposures that might lead

to hearing loss. In this study, a literature review was conducted to provide knowledge and

information on topics related to noise exposure. Noise dosimeters and sound level meters were

utilized to conduct the study. The results of the study showed that Company XYZ is in

compliance with OSHA regulations for noise exposure and there is no need for implementing

engineering or administrative controls in the sampled area. However, Company XYZ is not

meeting ACGIH recommendations for noise exposure and there is a need for implementing a

hearing conservation program. The results of this study guided the researcher to believe that

there are several improvements that could be implemented to enhance Company XYZ’s current

protection against noise exposure. Several recommendations have been provided to Company

XYZ to increase the effectiveness of the existing hearing conservation program.

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Acknowledgement

I would like to express my sincere appreciation for my thesis advisor Dr. Bryan Beamer

for assisting me throughout the thesis process as well as graduate career. My appreciation and

gratitude extends to the environmental, health, and safety coordinator at Company XYZ for his

assistance and friendship, in which I will always remember. Finally, I would like to thank my

family for the many years of support they have given me throughout my undergraduate and

graduate studies.

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Table of Contents

............................................................................................................................................. Page

Abstract ...................................................................................................................................... 2

Chapter I: Introduction .............................................................................................................. 6

Statement of the Problem ................................................................................................. 7

Purpose of the Study ........................................................................................................ 7

Goals of the Study ........................................................................................................... 7

Significance of the Study ................................................................................................. 7

Assumptions of the Study ................................................................................................ 8

Definition of Terms ........................................................................................................ 8

Limitations of the Study ................................................................................................. 9

Chapter II: Literature Review ................................................................................................... 10

Properties of Sound ...................................................................................................... 10

Health Effects of Occupational Noise ........................................................................... 12

Noise Regulations and Standards .................................................................................. 16

Types of Occupational Noise ........................................................................................ 19

Measurement of Noise .................................................................................................. 20

Noise Control Strategies ............................................................................................... 22

Chapter III: Methodology ......................................................................................................... 24

Subject Selection .......................................................................................................... 24

Instrumentation ............................................................................................................. 24

Data Collection Procedures ........................................................................................... 24

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Data Analysis ............................................................................................................... 25

Calculations .......................................................................................................................26

Chapter IV: Results and Discussion .......................................................................................... 28

Overview of Data ......................................................................................................... 28

Process Explanation ...................................................................................................... 30

Figure 1: Napkin Line Number One Process .................................................................. 30

Sound Level Meter Measurement ................................................................................. 31

Table 1: Sound Level Meter Measurements .................................................................. 31

Dosimeter Measurement ............................................................................................... 32

Table 2: Noise Dosimeter Measurements ...................................................................... 34

Time Weighted Average (TWA) Calculation ................................................................ 35

Current Training Practices ............................................................................................... 36

Chapter V: Conclusion and Recommendations ......................................................................... 36

Purpose Statement ........................................................................................................ 36

Conclusion ................................................................................................................... 36

Recommendations ........................................................................................................ 37

Recommendations for Further Study ............................................................................. 38

References ............................................................................................................................... 39

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Chapter I: Introduction

Today, nearly 30 million people in the United States are exposed to hazardous noise. For

more than two decades, noise-related hearing loss has been considered as one of the largest

occupational-health concerns in the work force in the United States. Noise in industries is

defined as an excessive level of sound produced by a mechanical system. Exposure to high levels

of noise can cause people to lose the ability to concentrate on certain activities in daily life such

as conversations. In addition, the existence of loud noise in the workplace can affect employees

by causing psychological stress, irritability, fatigue, and reduced productivity. The ultimate result

of exposure to high levels of noise is permanent hearing loss, which can not be corrected by

either hearing aids or ear surgery. Consequently, hearing loss has become a vital safety concern

in industries in the United States (Occupational Safety and Health Organization [OSHA], n.d).

The Occupational Health and Safety Administration (OSHA) has implemented the

conservation hearing loss program as a result of the employees suffering hearing loss. OSHA’s

general industry standard, 29 CFR 1910.95 (c)(2), requires the implementation of the hearing

conservation program when employee noise exposure exceeds an 8 hour time weighted average

(TWA) sound level of 85 decibels measured on the A scale (dBA) and 5 dB exchange rate.

The risk of employees’ hearing loss can be reduced by controlling the occupational noise

exposure through implementing engineering control, administrative control, and personal

protective equipment (PPE). The recommendation for engineering control is to control the source

of the noise, the noise transmission path, and noise at the work level (Barrientos, Lendrum, &

Steenland, 2004). Administrative controls could reduce noise exposure by adjusting the time the

worker spent in a noisy area and implementing a job rotation. PPE provides reduced noise

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exposure by wearing the proper PPE at all times to minimize the exposure when engineering and

administrative controls do not provide sufficient protection (Jensen, Jokel, & Miller, 1978).

Company XYZ employs more than 245 employees in Eau Claire, Wisconsin. The

company manufactures and converts bathroom and facial tissue. It also offers household towels,

napkins, and paper rolls. Company XYZ has been serving the retail sector in the United States

since 1882 and produces over 50,600 metric tons of tissue paper annually.

Statement of the Problem

Workers at company XYZ are exposed to high noise levels over an 8-hour TWA. High

noise exposure places employees at risk of developing hearing loss.

Purpose of the Study

The purpose of this study was to identify and evaluate the noise exposures at XYZ

Company and provide recommendations to reduce or eliminate the noise exposures that might

lead to hearing loss.

Goals of the Study

The goals of this study are to:

1. Gather and evaluate the current noise exposures that Company XYZ experiences.

2. Determine whether the noise exposures exceed OSHA standards and regulations.

3. Examine the feasibility of the current controls used by Company XYZ to reduce the noise

exposures.

Significance of the Study

The first major justification as to why it is crucial to conduct this noise study on

Company XYZ is that it will preserve employees’ hearing. In fact, employees are the main asset

and resource of the company. Protecting the hearing of employees is significant not only for

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deficient performance and governmental compliance issues in the work environment but also for

the quality of employees’ lives outside of work. Second, from a financial standpoint, the higher

the exposure to excessive noise in the workplace, the greater the likelihood that the company will

commit governmental violations and increase its workers compensation costs, which ultimately

affects its bottom line. Therefore, this study would help Company XYZ protect its employees

from exposure to excessive noise as well as determine its level of hearing compliance with

governmental regulations.

Assumptions of the study

The assumptions of this study are:

All subjects who participated in the study were of normal health.

All employees were performing typical workloads while being studied.

The information provided by Company XYZ is accurate.

Definition of terms

Decibel (dB). Sound level units

dBA. Sound level in decibels read on the A-scale of sound level meter. A-scale function is

similar to the human ear on detecting very low frequencies. Thus, it is the best scale used for

measuring general sound levels.

OSHA. The Occupational Safety and Health Administration, a governmental agency that

enforces occupational safety issue such as noise.

Noise dosimeter. An instrument used to determine the employees exposure to a noise hazard

over a period of time (NSC, 1988).

Time-weighted average sound level. Summation of amount of noise over a period of time is

usually displayed in an eight-hour workday.

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Limitations of the study

The limitations of this study are:

The results of the study are only particularize to Company XYZ and may not be valuable

for other organizations.

The noise dosimetry testing used in the study was conducted during the day shift.

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Chapter II: Literature review

The purpose of this study was to identify and evaluate the noise exposure at Company

XYZ and determine the level of noise to which its employees are exposed. In order to properly

identify a noise exposure hazard, one must have an understanding of various topics related to

noise and hearing loss. Therefore, this chapter will include a discussion of properties of sound,

the health effects of occupational noise, noise regulations and standards types of occupational

noise, measurement of noise, and noise control strategies.

Like other senses in our bodies, humans often do not recognize the importance of hearing

until they lose it. Hearing is crucial for both worker performance and social interactions and

communications. Humans perceive sound when pressure variations within the air are detected by

physiological hearing functions means. Hertz (Hz) is the unit used to measure frequency and the

units of decibels (dB) are used to measure variations in sound detected by a human ear based on

the perceived loudness (sound-pressure level). In fact, non-impaired human hearing can detect

frequencies that range from 20 Hz to 20,000 Hz (National Safety Council, 1988).

In 2001, The National Institute for Occupational Safety and Health (NIOSH) reported

that the second-most self-reported type of occupational injury was hearing loss. In the late 1970s

and early 1980s, the reported worker compensation claims related to occupational hearing loss

were an estimated $835 million during a 10-year period (Seidman, 1999). According to the

World Health Organization (WHO), hearing loss from occupational noise is the largest

compensable health hazard in industrialized countries.

Properties of Sound

In this section, several physical properties of sound will be explained. The basic

definition of sound is a pressure variation the human ear can detect. Frequency, which is

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measured in hertz (Hz) represents the number of variations or cycles that occur each second. The

produced sound wave determines the actual sound, which includes sound intensity and sound

frequency. The frequency, as stated above, is variations per second (Hz). The normal range of

frequency for human is typically between 20 and 20,000 Hz. Employees will likely perceive

high-frequency noise as more annoying than low frequencies (National Safety Council, 1988).

Therefore, high-frequency noise will receive more attention than low frequencies because it is

more likely to cause adverse health effects.

Wavelength is one of the sound properties that employed in developing engineering

controls to minimize noise exposure. Wavelength is defined as the distance that a sound wave

travels in one cycle, or the distance between two analogous points on the successive parts of a

sound wave. Wavelength and frequency are inversely proportional, connecting the direction and

duration a sound wave travels with the speed of sound. Typically, high-frequency sound has

shorter wavelengths than low frequency. Therefore, high-frequency can not travel around

barriers as easy as low frequency does. Thus, engineering controls such as sound barriers or

walls would not work for low frequency sound. However, these engineering controls work well

in averting high-frequency sound (National Safety Council, 1988).

Amplitude is the degree of change in the refraction and compression of pressure

variations in the sound waves. Due to the high sensitivity of the human ear, it perceives pressure

variations as loudness. Therefore, there is a directional relationship between the sound wave and

the amplitude. These sound waves are measured as sound-pressure level (SPL) and expressed in

decibels. The threshold of audibility at 20 micropascals, 1,000 Hz, is used as the reference

pressure to compute the sound-pressure level. Also, they are proportional to the square of the

measured sound pressure (World Health Organization [WHO], 1999).

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The human ear, which acts as a microphone or transducer, is the organ responsible for

receiving sound. Once a human ear receives sound waves from any source of sound, it

transforms them into nerve impulses. These nerve impulses are interpreted into sound by the

brain. The main function of the brain is to filter unwanted sound or annoying noise from the

normal sound (Alberti, 2001).

Health Effects of Occupational Noise

In this section, adverse health effects of occupational noise will be discussed. Many

employees are not aware of how predominant noise in the work environment is. Sound

frequency, exposure duration, exposure pattern, and sound intensity are factors that can

determine whether noise can inflict hearing loss. Frequencies above 1,000 Hz are more likely to

cause damage to a person than frequencies below 1,000 Hz. In addition to the noise exposure

factors listed above, there are other components related to the employee himself and the work

environment that may contribute to the level of hearing loss experienced by employees. These

components include employee age, type of occupational noise, individual susceptibility, the

environment in which the noise occurred, diseases of the ear, and relative distance from the

source of the noise (Royster, 2009).

A study conducted by the U.S. Public Health Service indicated that regardless of any

occupational noise exposure, 20% of all employees between the ages of 50 and 59 will develop

hearing loss. In cases of presbycusis, where hearing loss develops as a natural occurrence of age,

it is not probable for a person to experience significant hearing impairment (Joseph, Anticaglia,

and Cohen, 2010). Another study conducted by the U.S. Public Health Service indicated that half

of the estimated 21 million Americans who are experiencing hearing impairments attribute their

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losses to noise exposure. A combination of hearing loss caused by noise exposure and the natural

effects of presbycusis could result in significant auditory and non-auditory effects.

From a duration standpoint, there are two categories of occupational hearing losses. First,

there are temporary threshold shifts (TTS), which a short-term decrease in hearing abilities.

Second, there are permanent threshold shifts (PTS), which are based on an individual’s threshold

of hearing. The susceptibility of an individual’s ears determines the degree of both TTS and PTS.

In addition, susceptibility is different from one human ear to another based on the frequency of

the noise encountered (Berger, 2000).

Sound intensity and duration of noise exposure play a major role in determining the

degree of TTS. During the first few hours of exposure, the employees experience the greatest

amount of temporary hearing loss. After a short period of time, an individual may become used

to the loud noise because the cilia have become exhausted and they can not function well. A

healthy person may experience TTS when noise levels exceed at least 80 dBA. In case when

noise levels exceed 80 dBA, the potential for TTS to occur depends mostly on the intensity of

sound.

Accumulated temporary threshold shifts are the major cause of permanent hearing loss.

Individuals who routinely experience TTS are more likely to incur long-term hearing

impairments. Permanent damages to the cilia in the ear or the auditory nerve are the major cause

of long-term hearing losses. Sensory-neural hearing loss, which means damage to the auditory

nerve, usually occurs at the 4,000 Hz frequency range. The hearing loss will expand across 2,000

or 3,000 through 6,000 Hz when an individual continues exposure to high-frequency noises

(Berger, 2000).

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Noise health effects are often categorized into auditory effects, which include hearing

impairment and hearing loss, and non-auditory effects such as cardiovascular effects and job-

performance impairment. According to the World Health Organization, 278 million people are

experiencing hearing impairment, which means partial or complete loss of hearing in one or both

ears. An individual might be hearing impaired for several reasons such as exposure to chemicals

that damage the organs of the ear, sustaining head injury, age, acquiring infectious diseases, and

exposure to excessive noise. In fact, combination of both exposure to excessive noise and other

causes of hearing impairment can lead to a synergistic effect (Barrientos, Lendrum, and

Steenland, 2004).

Sensorineural and conductive hearing loss are the two major types of hearing impairment.

Sensorineural hearing impairment is irreversible and occurs in the inner ear, whereas conductive

hearing impairment is reversible and occurs in the outer and middle ear. Furthermore, there is an

8% risk of workers experiencing sensorineural hearing impairment when the noise exposure is

greater than 85 dBA in the work environment (NIOSH, 1998).

The most common form of hearing loss in industrialized countries is called Noise -

Induced Hearing Loss (NIHL), which is simply the result of damage to the sensory hair cells in

the cochlea (NIOSH, 1998). There are several factors that contribute to NIHL, such as duration

of exposure, sound frequency, SPL, and individual susceptibility. Sensory hair cells can be

initially repaired when they are inflamed by sound energy. Also, they can recover after exposure

to a loud noise for a short period of time followed by a rest or a period of quiet time.

Nevertheless, hair cells can be destroyed when they are exposed to excessive noise or repeated

inflammation from sound energy. Due to the fact that humans can not regenerate hair cells, the

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result of damaged hair cells is PTS (permanent threshold shift) or permanent hearing loss

(Alberti, 2001).

Cardiovascular and impaired job performance are non-auditory effects of exposure to

high levels of noise. Experiments on animals and epidemiological studies are methods used to

examine the cardiovascular effects of noise exposure in humans. According to a study that

examined the arterial vasculaturer of employees during sleep and eight-hour work shifts,

employees exposed to noise levels of 59 dBA had lower blood pressure and greater arterial

elasticity than workers with 85 dBA noise exposures. Many studies have found a positive

relationship between use of hearing protection and healthy blood pressure (Chan, Chang, Jain,

Lin, and su, 2007).

It is clear that noise exposure is one of the factors that cause job performance impairment.

However, noise exposure is different from one task to another, which makes it hard to compare

accident frequency rates between different tasks. Cohen (1973) conducted a study where he

compared two different groups of workers who have similar work experience and age. He found

that employees exposed to a noise level greater than 95 dBA had a 35% higher accident rate than

employees exposed to less than 80 dBA. In addition, noise exposure has a negative impact on

communication between employees in the workplace. He also proved that the necessary reaction

time for performing a task increases and the probability of correct responses decreases because

of noise exposure.

In addition to all the adverse health effects listed above, noise exposure has several

psychological and physiological effects on humans. There is increasing evidence that noise is

one of the major causes of stress-related illnesses such as ulcers, allergies, hypertension, and

neurological disorders. Exposure to high noise levels is also a factor in illnesses related to fear,

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nervousness, disturbed sleep, and psychosomatic conditions. In addition, high noise levels are

known to impede adaptation to night vision and also elevate thresholds of flicker fusion.

Constant excessive noise tenses the body’s metabolism and releases adrenaline. It also

causes body fatigue and deteriorates physical conditioning, which means the heart is being

forced and constricted by the blood vessels to work harder and pump the same amount of blood

to vital organs, which might cause cardiovascular effects such as cardiac hypertension (Clayton,

1994).

A study sponsored by NIOSH and conducted by the Raytheon Service Company found a

negative correlation between noise and health. The study examined the medical records of

factory employees who were exposed to noise levels above 95 dBA. These workers were

compared to employees exposed to noise below 80 dBA. The results indicated a statistically

significant increase in circulatory and cardiovascular disorders among workers exposed to higher

noise levels.

Noise Regulations and Standards

The OSHA standard for occupational noise exposure is 29 CFR 1910.95. This standard

institutes an 8-hour shift TWA permissible-exposure limit (PEL) of 90 dBA using a 5 dB

exchange rate. Exposures at 90 dBA were expected to present a 25% increase in the risk of

hearing loss of 25 dB at 1 Hz, 2 Hz, 3 Hz, and 4 Hz (OSHA, n.d). The American Conference of

Governmental Industrial Hygienists (ACGIH) and NIOSH have suggested using 85 dBA as the

exposure limit for an 8-hour TWA and 3 dB exchange rate (Gilbert, 1997).

A study compared the OSHA criteria, 90 dBA 8-hour TWA, 5 dB exchange rate and 80

dBA threshold to the ACGIH and NIOSH criteria, 85 dBA 8-hour TWA, 3 dB exchange rate,

and 80 dBA threshold. The study included 50 employees performing different tasks with two

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dosimeters for each worker. One of the dosimeters was set with ACGIH and NIOSH criteria and

the other one was set with OSHA criteria.

The purpose of the study was to show how the OSHA-criteria algorithm underestimates

the actual noise exposure in cases of variable noise levels. The measurement of the OSHA-

criteria dosimeter was less than the measurement of the ACGIH and NIOSH criteria dosimeter

by 0.2 dBA to 12.6 dBA. The result of this study shows that the reported exposure of noise levels

using OSHA criteria is less than the actual noise levels that employees are exposed to, which

means the chance for NIHL to occur is higher than what would be predicted from the reported

exposure levels (Petrick, 1996).

Harris (1991) recommended implementing a device that measures levels between 80 dB

and 130 dB in order to control workers’ noise exposure. Under the general industry standard,

(29 CFR1910.95) (b) (1), organizations are required to implement engineering or administrative

control when occupational employees are exposed to noise levels that exceed OSHA’s

acceptable dose of 1.0. If occupational workers are exposed to noise levels that exceed 4.0, an

employer is required to implement engineering controls to minimize the noise exposure. In

addition, if these engineering controls reduce the noise levels below a worker dose of 4.0, yet it

still exceeds a dose of 1.0, the employer has to provide hearing-protection devices (HPD) for the

occupational employees.

Under OSHA regulations, an employer is required to implement HPD for workers based

on the following conditions: first, when the employer does not perform a baseline audiometric

test; second, when workers’ doses exceed 1.0; third, when a worker experiences standard

threshold shift (STS), which refers to a 10 dB reduction in noise sensitivity that a worker is able

to recognize at the frequencies of 2,000 Hz, 3,000 Hz, and 4,000 Hz (OSHA, n.d).

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In order to determine whether STS has occurred, organizations are required to perform

annual audiometric tests to determine the degree of worker hearing sensitivities, which are based

on the results from the previous year. STS occurs for an employee when the test result indicates

change with an average sensitivity that is greater than or equal to 10 dB in the employee’s ability

to perceive noise levels (NIOSH, 1996).

Employees who are exposed to a TWA of 85 dB or higher have the right to receive

hearing protection from their employer at no cost. The hearing protection must be able to

decrease the noise levels to TWA of 85 dB for employees who have experienced STS and 90 dB

for other employees. With help of a person who is trained in fitting hearing protection,

employees can choose the most suitable size and type of hearing protection for their work

environment. It is the employer’s responsibility to ensure that employees wear hearing protection

properly. Employers are responsible for conducting annual training for their employees who are

exposed to a TWA of 85 dB. The training should cover effects of noise, the pros and cons of

different types of protective equipment, aspects of audiometric testing, personal hearing

protective devices, and characteristics of noise attenuation of hearing protection (Greene, 1992).

The purpose of audiometric testing is to determine whether hearing loss has occurred.

Employers are required to provide, at no cost, audiometric testing to all employees who have

average exposure levels above or equal to 85 dB. The test should include baseline audiograms

from previous years and annual audiograms to compare how hearing has decreased. Also, the test

should be taken separately for each ear, and the employee must not have been exposed to

workplace noise for at least 14 hours prior to the test.

Moreover, audiometric test results must be kept for each employee’s duration of

employment and two years for the noise exposure measurement records. The name and job

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classification of the employee, the date and time, the tester’s name, and the date of exhaustive

calibration measurements of the sound-pressure levels should be included in the results. In

addition, the result should include the employee’s most recent noise exposure measurement and

the serial number of the audiometer. Employers must provide records when they are requested by

a representative designated by the employee, former employee, and current employee (Greene,

1992).

Types of Occupational Noise

Occupational noise can be divided into three categories: continuous, intermittent, and

impact. Each one of these types has a slightly different effect on the human ear than the other

types. The first type of occupational noise is continuous noise, which is known as a constant

spectrum and level of broadband noise generated by power equipment or any source of noise in

the work environment. Normally, employees are exposed to average noise levels during a period

of eight hours per workday (National safety council, 1988). Continuous noise is one of the

occupational noise types that are regulated by the Occupational Safety and Health

Administration (OSHA, n.d).

Intermittent noise is the second type of occupational noise, and it occurs when

occupational noise has a gap between repetitions or when employees are exposed to non-constant

sound-pressure levels several times during their work shift. Researchers recommended that

specific equipment such noise dosimeters should be used to measure this type of noise especially

when employees constantly move between noisy work areas and quiet environments (National

safety council, 1988).

The third type of occupational noise is called impact or impulse noise, which refers to

sharp and short bursts of noise that last for a duration of half second or less and does do not

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occur more than one time per second, such as striking two objects together, explosions, and the

firing of weapons. Workers are not supposed to work in an environment where impact or

impulsive noise exceeds a sound-pressure level of 140 dB for each exposure. Researchers

suggested that all types of potential occupational noise that employees are exposed to in the

workplace should be evaluated and controlled if they exceed the limits of standards and

regulations (National safety council, 1988).

Measurement of Noise

Decibels (dB) are the units used to measure the loudness and intensity of sound. The

number 0.0002 mbar is used as a reference pressure to the logarithms of the ratio of the sound

pressure. In order to measure noise exposure, sound-pressure level (SPL) is used. SPL=20 log

(P/PO) where P is the sound pressure and PO is the reference pressure 0.0002 mbar. Noise

intensity, sound frequency, and exposure duration are the major factors that need to be

considered when measuring noise.

There are various instruments used to measure noise in the work environment. These

instruments are appropriate for different types of noise exposure and they can be employed

depending on the noise exposure encountered in the workplace. When measuring noise, different

frequency measurements are grouped together automatically by the instrumentation to achieve

one average reading (Malchaire, 2001).

Some instruments contain different scales to calculate the average reading of the noise

measurement. The most frequently used scales are labeled “A,” “B,” and “C.” Scale A is the

most frequently employed in the measurement of industrial and environmental noise. Scale A is

mostly used to indicate low frequencies because the human ear does not readily perceive them.

Scale B also discriminates against low frequency sounds. In fact, scale B is the least common

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used because it serves the same function scale A does with lesser extend. In contrast, scale C

does not discriminate against the presence of low frequencies. It actually reflects sound as it

occurs in nature, without bias for human response. Therefore, scale C is useful in measuring the

effectiveness of hearing protectors in the work environment (Gane, 1986).

The most common sound measurement instruments are the sound-level meter (SLM), the

octave-band analyzer, and the noise dosimeter. The purpose of the study and characteristics of

sound are the major factors that determine the type of instruments used to measure the noise

exposure (Malchaire, 2001).

A sound-level meter is a sensitive direct instrument with a microphone used to provide

instantaneous measurement of noise exposure. An SLM measures the electrical signal emitted

from the microphone, then converts it to decibels, which are shown on a digital screen. The most

frequent use of an SLM is for settings in which the employee noise exposure is constant

throughout the workday, for the design of engineering controls, and for achieving general

readings of noise levels. The SLM has a limited capability of determining employees’ average

noise exposures throughout the workday if there are significant variations in noise levels

(National Safety Council, 1988).

An octave-band analyzer is a noise-measurement instrument that amplifies microphone

signals to measure noise levels at separate frequencies. It is believed that octave-band analyzer is

the most effective instrument for evaluating engineering controls to reduce noise levels. In fact,

the wide bandwidths are preferred over narrow bandwidths for sound analysis. Therefore, they

use few measurements to provide spectral distribution of pressure (National Safety Council,

1988).

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The noise dosimeter is the most preferred instrument to evaluate noise exposure because

it provides instantaneous measurement and measures noise levels over time to achieve a time-

weighted average. Noise dosimeters are also helpful for calculating employees’ exposure to

noise in cases where the levels of noise vary throughout the workday. After evaluating and

recording SPL values, noise dosimeters calculate the employees’ dose based on the criterion set

in the meter. Noise dosimeters are suitable for most types of exposure to occupational noise,

such as intermittent, impulse or impact, and fluctuating (Malchaire, 2001).

Noise Control Strategies

The three primary methods used to control occupational noise exposure are engineering

controls, administrative controls, and personal protective equipment (PPE). Each strategy has its

own advantages and disadvantages. However, engineering controls are known to be the most

efficient and desirable methods used to attenuate occupational noise exposure.

Engineering controls can be categorized into three classifications: minimizing noise at the

source, sound-absorbing control, and masking sounds (Kurtus, 2007). Reducing noise at the

source can be obtained by adding anti-vibration systems or mufflers. Sound absorbing control

includes engineering-control activities such as placing sound-absorbing materials between the

employee and the noise source. Sound-absorbing materials can be any material that has the

ability to attenuate noise, such as fully or partially reticulated plastic foam, glass fiber, and

mineral rock (Seybert, 2002). Sound masking is actually covering noise, not minimizing the

sound. An example of masking noise would be playing natural water sounds to cover an

annoying noise. In fact, noise masking adds noise to the existing noise, which might create more

damage to the hearing. Routine maintenance on machines, such as tightening and lubrication, can

also play a great role in attenuating occupational noise exposure (Wilkinson, 2002).

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If engineering controls are not feasible or they do not attenuate noise levels to meet

occupational standards and regulations, organizations may seek administrative controls. There

are no physical activities involved in administrative controls, so they do not actually attenuate

noise. In fact, they are rule-making activities that minimize the duration of exposure to

occupational noise. For example, employee relocation, which is a form of job rotation, allows

workers an adjustment period to regroup after occupational noise exposure. If job rotation or

other administrative controls are not applicable, the organization should provide enclosed booths

that limit employees’ exposure to occupational noise levels (NIOSH, 1996).

The last alternative for occupational noise reduction is personal protective equipment.

There are abundant kinds of ear protection such as earmuffs, which is the most effective personal

protective equipment for high-frequency noise exposures. Earplugs are effective for low-

frequency noise exposure, yet many employees insert them incorrectly, so they annoy the inner

part of the ear and become ineffective. Ear protection does not remove the noise exposure, but

acts as a barrier between the inner ear and the noise to protect the ear from the exposure.

Personal protective equipment has countless limitations; for example, employees who wear PPE

are still exposed to certain levels of noise because, as sound passes through tissues and bones, it

can reach the inner ear. This can happen if there are leaks in the protection equipment or if the

occupational noise causes vibrations in the protective equipment. Personal protective equipment

should be the final option for reducing occupational noise (Harris, 1991).

24

Chapter III: Methodology

The purpose of this study was to identify and evaluate the noise exposure at napkin-line

number One in the Converting Department at Company XYZ and determine the level of noise to

which its employees are exposed. The goals were to gather and evaluate the current noise

exposures that Company XYZ experiences, determine whether the noise exposures exceed

OSHA standards and regulations, and examine the feasibility of the current controls used by

Company XYZ to reduce the noise exposures. This chapter will discuss subject selection,

instrumentation, data collection procedures, and data analysis.

Subject Selection

Company XYZ was selected for this study based on the relative ease with which the

researcher was able to contact and collect information from the risk control professional. The

subject operates napkin-line number one in the converting department and works three to four

days a week with average twelve hours a day including one-hour break. The subject selected had

the highest exposure to occupational noise levels within Company XYZ’s facilities. To ensure

confidentiality, company and subject names were withheld from this study.

Instrumentation

In order to determine an accurate measurement of employees’ occupational exposure to

noise levels at Company XYZ, both noise dosimeter and hand held sound-level meter were used.

The noise dosimeter was calibrated to 114 dB and the sound level meter was set to measure noise

levels between 70 and 140 dBA. All instruments were calibrated before and immediately after

the noise exposure was monitored according to the manufacturer’s recommendations.

Data Collection Procedures

Once the noise dosimeter and sound-level meter were calibrated. The noise dosimeter

25

was placed on the employee’s pocket and the microphone was attached to the clothing of the

employee who was working on napkin-line number One in the Converting Department, which is

the noisiest workstation within the facility of Company XYZ. The sound level meter was utilized

to measure the noise on each process involved in napkin-line number one. The sound level meter

was placed three feet away from the noise source, which is the normal distance for employees to

perform that job. After the noise dosimeter and sound-level meter were set up at the selected

employee and the chosen distance, the researcher observed the employees’ behavior and

determined how many employees were wearing their noise-reducing personal protective

equipment (PPE). In addition, the researcher observed the feasibility of current engineering

controls in attenuating noise exposure. During the sampling, the researcher asked a series of

questions related to the components of the hearing-conservation program. After the completion

of the noise monitoring, the dosimeter was removed and paused to stop data collection. At the

end of the sampling period, the instruments were calibrated and all machine data was recorded

on the data sheet. For better interpretation of the data collected, the information stored in the

dosimeter was downloaded to a personal computer with professional computer software.

Data Analysis

After the noise dosimeters’ readings were recorded, the data was analyzed to determine

the highest noise-exposure level at Company XYZ. The measured noise levels were then

compared to OSHA standards and regulations to determine Company XYZ’s compliance with

these standards and regulations. The results also will be utilized to determine the compliance of

Company XYZ to ACGIH recommendations. The dosimeter can compare four criteria at one

sampling. The researcher chose OSHA PEL and HC, and the ACGIH; the OSHA criteria use 90

dBA and 5 dB exchange rate. The only difference between OSHA PEL and HC is that the PEL

26

use 90 dBA threshold and HC use 80 dBA threshold, which means values less than this limit will

be ignored. In addition, the data was compared to NIOSH criteria, which use 85 dBA, threshold

80 dBA, and 3 dB exchange rate. The researcher used true Leg for the fourth criteria and it was

identical to NIOSH criterion without threshold. The data also was utilized to determine whether

the personal protective equipment provided by Company XYZ is adequate in protecting

employees from occupational noise levels. Finally, the effectiveness of employees’ compliance

in wearing PPE with the Company XYZ’s hearing-conservation program was analyzed.

Calculations

In order to identify if Company XYZ have to implement either engineering or

administrative controls the noise dose must be compared to one based on 90 dBA threshold and 5

dB exchange rate. If the dose is greater than one, the company must implement either

engineering or administrative control. If the dose is less than one, the dose then compared to the

hearing conservation criteria. The following formula is used to calculated the dose based on

OSHA regulations:

Dose = Sampling time/ Reference duration

And the following formula is used to calculate the reference duration:

Reference duration = 480/2(SPL - 90)/ 5

To identify if Company XYZ is meeting ACGIH recommendations, the noise dose must

be compared to one based on 80 dBA threshold and 3 dB exchange rate. If the dose is less than

one meaning the Company is meeting the recommendations. However, if the dose is greater than

one that means the noise level is higher than the recommended noise level exposure by ACGIH.

The following formula is used to calculated the dose based on ACGIH recommendation:


27



Due to the limited accessibility to the facility and the time awarded, the investigator was

able to sample only for thirty minute. Based on the fact that TWA value should only be used for

full shift of eight hour sampling, and the dosimeter function assumes that the un-sampled time to

be zero when sampling for less than eight hours. Therefore, the time-weighted average was

calculated by assuming that the sound level measured in the sampling time equals the exposure

during eight-hour work shift and by using the following equation:

TWA = 16.61 Log 10Average Sound Level/ 16.61 Sampling time _________________________________________________

8 Hours

28

Chapter IV: Results and Discussion

The purpose of this study was to identify and evaluate the noise exposure at napkin-line

number one in the Converting Department at Company XYZ and determine the level of noise to

which its employees are exposed. The goals of this study were to:

1. Gather and evaluate the current noise exposures that Company XYZ experiences.

2. Determine whether the noise exposures exceed OSHA standards and regulations.

3. Examine the feasibility of the current controls used by Company XYZ to reduce the noise

exposures.

This chapter will discuss the results of the study including the noise monitoring in napkin

line number one. In addition, Company XYZ compliance to OSHA noise regulations and the

adequacy of hearing protection provided by Company XYZ to their employees will be discussed

as well. This chapter will discuss the training activities for employees at Company XYZ as they

related to hearing conservation program.

Overview of Data:

Data was collected on April 23, 2013 during the first work shifts at Company XYZ using

Quest Technologies dosimeter Model NoisePro DLX. The collected data represent the exposure

to noise experienced by the employee wearing the personal noise dosimeter. The first work shift

at Company XYZ has the greatest number of tasks performed and number of employees. The

sound level meter was also utilized to measure the sound level at each process involved in napkin

line number one. All employees monitored were wearing hearing protection and anti-static shoes

all the time.

The noise dosimeter used in the study has the ability to measure various noise levels such

as the maximum level, impulse sound during the sampling period, and the average of all the

29

recorded sounds during sampling. In addition, it has the ability to show exposure information in

form of dose, which is in percent of the OSHA permissible exposure. Typically, the TWA should

only be used for full shift of eight hour sampling, so the dosimeter assumed the un-sampled time

to be zero when sampling for less than eight hours. This noise assessment does not provide

Company XYZ the exposure during an entire working shift. However, it provides noise levels

during the sampling time. Therefore, the TWA values shown in this study are not accurate

because the sample times were not based on eight hours work shift. Similarly, when comparing

to OSHA regulations, this study still not accurate as OSHA 90 dBA is based on eight-hour work

shift.

30

Process Explanation:

Figure 1. Napkin line number One process

The following list includes the process involved in napkin line number one:

1) The employee places the rolls in roll circles.

2) The machine pulls the rolls from the circles.

3) The machine divides the rolls into four lines.

4) The rolls come out in a group of 100 napkins.

5) The napkins leave production line number 1.

6) Computer desk and quick break area.

Roll

1

2

3

4 5

6

Roll

Roll

Roll

Roll

Roll

Roll

Roll

31

Napkin-line number one is the first stage in the operation process of napkins in the

converting department. Products that leave napkin line number one are sent to other lines for

further process, such as treatment and packaging.

Sound Level meter Measurement:

As stated in Chapter III, noise level surveys were taken in napkin line number one. Table

1 (below) indicates the results of sound level meter readings. Measurements were taken at the

locations of each process involved in napkin line number one as explained in Figure 1 and they

are based on ten seconds interval. As displayed in Table 1, location number three where

employee watch the machine when it cuts rolls into lines seems the nosiest area, which requires

the employee to be aware of excessive noise level in that area.

Table 1

Sound Level Meter Measurements Sound Level Meter Data for April 23, 2013, 1:00pm – 1:30pm (1st shift) *All measurements are in dBA

Location Average Maximum Minimum Peak

(1) Putting the

rolls

84.5 85.3 83.7 98.4

(2) Machine

pulling the rolls

92.2 92.9 91.1 105.6

(3) Machine

cutting the rolls

into four lines

94.3 96.2 93.3 109.9

(4) Napkin 90.0 93.2 98.1 105.6

32

coming out of

machine in group

of 100

(5) Rolls moving

to the next line

88.8 94.1 87.1 111.2

(6) Rest area and

computer work

87.2 89.2 86.2 101.6

Below is an explanation for Table 1 row headers:

- Average is the average sound level measurement during the sampling period.

- Maximum is the highest measured sound level during the sampling time.

- Minimum is the lowest measured sound level during the sampling period.

- Peak is the maximum value reached by the sound pressure. Unlike maximum, there is no time-

constant applied for peak and the signal has not through root mean square circle or calculator.

Dosimeter Measurement:

The noise dosimeter was sat to measure the noise level based on the following four

functions; OSHA PEL, OSHA HC, ACGIH, and User 4. The parameters of these functions were

illustrated in Chapter III. Due to the limited accessibility to the facility and the time awarded, the

investigator was able to sample only for thirty minute. Therefore, the time-weighted average was

calculated manually based on the assumptions made in Chapter I. the TWA calculation will be

explained in a separate section later.

33

In order to determine the compliance of Company XYZ with OSHA regulations and how

well they are meeting ACGIH recommendations with regard to noise exposure, each reading was

collected using a noise dosimeter as shown in Table 2 (below). As indicated in the assumptions

in Chapter I, the average sound level sampled equals the sound level in eight-hour work shift,

which means the average sound level equals the TWA. Once the data was gathered, it was

compared to the OSHA standards of 90 dBA in an eight-hour period. The measured OSHA

permissible exposure level is 86.3 dBA, which is below OSHA standard of 90 dBA.

To identify if Company XYZ have to implement either engineering or administrative

controls the noise dose must be compared to one based on 90 dBA threshold and 5 dB exchange

rate. If the dose is greater than one, the company must implement either engineering or

administrative control. If the dose is less than one, the dose then compared to the hearing

conservation criteria. The following formula is used to calculated the dose based on OSHA

regulations:




As shown in Table 4-2, the measured sound pressure level (SPL) based on OSHA PEL criteria is

86.3 dBA, so the reference duration is 13.36 hours, and the dose is 8/13.36 which equals 0.59 <

1. This result indicates that Company XYZ is not required to implement engineering or

administrative controls.

In order to determine if Company XYZ needs to implement hearing conservation

program, the noise dose compared to half based on 80 dBA threshold and 5 dB exchange rate. If

the dose is greater than half, the company must implement hearing conservation program. If the

34

dose is less than half, there is no necessity to implement hearing conservation program. As

shown in Table 2, the SPL average based on OSHA Hearing Conservation (HC) criteria is 90.3,

and by using the same equations above, the dose is 1.04 > 0.5, which shows that Company XYZ

have to implement hearing conservation program.

To identify if Company XYZ is meeting ACGIH recommendations, the noise dose must

be compared to one based on 80 dBA threshold and 3 dB exchange rate. If the dose is less than

one meaning the Company is meeting the recommendations. However, if the dose is greater than

one that means the noise level is higher than the recommended noise level exposure by ACGIH.

The following formula is used to calculated the dose based on ACGIH recommendation:




As shown in Table 2, the measured sound pressure level (SPL) based on ACGIH criteria is 91.0

dBA, so the reference duration is 2 hours, and the dose is 8/2 which equals 4 > 1. This result

indicates that Company XYZ is not meeting ACGIH recommendations for noise exposure.

Table 2

Noise Dosimeter Measurements Noise Dosimeter Data for April 23, 2013, 1:00pm – 1:30pm (1st shift)

OSHA PEL OSHA HC ACGIH USER 4

Average 86.3 dBA 90.3 dBA 91.0 dBA 91.0 dBA

35

Time Weighted Average (TWA) Calculation:

Due to the limited accessibility to the facility and the time awarded, the investigator was

able to sample only for thirty minute. Based on the fact that TWA value should only be used for

full shift of eight hour sampling, and the dosimeter function assumes that the un-sampled time to

be zero when sampling for less than eight hours. Therefore, the time-weighted average was

calculated by assuming that the sound level measured in the sampling time equals the exposure

during eight-hour work shift and by using the following equation:

TWA = 16.61 Log 10Average Sound Level/ 16.61 Sampling time _________________________________________________

8 Hours

The investigator was able to calculate the TWA, which equals the average sound level measured.

Also, the result enables the investigator to compare the sound level to OSHA standards of noise

exposure. In addition, the sound level measured was compared to the engineering and

administrative controls criteria as well as the hearing conservation program criteria.

Current Training Practices:

Safety department at Company XYZ conducts annual training on hearing conservation

program including purpose of hearing protection devices, watching a video about the function of

the ear, effects of loud noises on the ear, and what the audiometric testing involves. Company

XYZ goal of conducting hearing conservation training is to enhance employees’ awareness and

meet legal requirements.

36

Chapter V: Conclusions and Recommendations

The purpose of this chapter is to discuss the data presented in Chapter IV and state

conclusions with regard to the results presented. This chapter also will provide recommendations

for improving Company XYZ performance regarding noise level exposure.

Purpose Statement:

The purpose of this study was to identify and evaluate the noise exposures at XYZ

Company and provide recommendations to reduce or eliminate the noise exposures that might

lead to hearing loss. The goals of this study were to gather and evaluate the current noise

exposures that Company XYZ experiences, determine whether the noise exposures exceed

OSHA standards and regulations, and examine the feasibility of the current controls used by

Company XYZ to reduce the noise exposures. This information was gathered throughout the use

of sound level meter and noise dosimeter. The noise dosimeter was placed in the employee’s

pocket and the windscreen was hanged in his shoulder. An analysis was conducted on Company

XYZ compliance with OSHA standards with regard to noise exposure. In addition, the employee

behavior and compliance in terms of wearing the proper personal protective equipment provided

was casually observed as well. An assessment was made on the current training practices

conducted by Company XYZ.

Conclusion:

While conducting this study, it was indicated that Company XYZ employees have

experienced hearing loss in the near past. It was found that area number three in line number one

where the employee observe the machine cutting the rolls into lines has the greatest exposure to

noise. The results show that the TWA of the sound level in the area sampled was within the

range of OSHA standards for noise exposure. In addition, the dosimeter readings show that

37

Company XYZ is meeting the engineering and administrative criteria for noise exposure. The

data also indicates that Company XYZ needs to implement a hearing conservation program to

meet both OSHA regulations and ACGIH recommendations for noise exposure.

Recommendations:

Even though the TWA was below the OSHA regulation for noise exposure, employees

may still experience hearing loss caused by continues exposure to excessive noise levels. Each

time employees exposed to excessive noise levels, they lose an amount of hearing to a point

where the ear can not recuperate all of the hearing lost which results in adverse health effects

such as hearing loss. Due to the fact that regulations provide minimum level of protection,

Company XYZ should set noise exposure objective at 10 decibels lower than OSHA regulations

in order to prevent hearing loss. Based on this study’s results and conclusions, the following

controls are recommended to be implemented to prevent hearing loss of employees:

Company XYZ could provide better quality hearing protection devices. The main feature

of these devices should be the ability to reduce noise to at least 10 decibels below the

current noise exposure. Company XYZ should pay attention to Noise Reduction Rate

NRR characteristic when buying new personal protective equipment.

Due to the fact that there is a great variation in noise levels within the facility of

Company XYZ, it is recommended that Company XYZ implement a job rotation for

employees as part of the administrative control to reduce the current noise exposure.

It is recommended that Company XYZ put more time and effort on training employees

on the hearing conservation program. In addition, it crucial to make sure that those who

provide the yearly training to employees in the program are knowledgeable on the topic

38

of hearing conservation. It is also important that Company XYZ motivates and

encourages its employees to be active participants in the training programs.

Recommendations for Further Study:

There are several recommendations that the investigator would like to provide to

Company XYZ for future improvement of the noise exposure. These are as follows:

It is recommended that another noise level survey based on eight-hour sampling

performed which entails personal monitoring for the duration of the work shift. A full

shift monitoring will provide the best representation of the noise employees are exposed

to as well as an accurate eight-hour time weighted average. This accurate information

allows for better comparison to OSHA standards, engineering criteria, administrative

criteria, and hearing conservation program criteria.

It is also recommended that another study conducted focusing on the current personal

protective equipment provided. This study should explore the effectiveness of the current

hearing protection devices and to what extend they reduce the current noise exposure

experienced. In addition, the study should clearly identify the NRR that the current

hearing protection provide, and recommend better PPE with more effective NRR if

needed.

39

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