ILO Noise at Work

7/27/2019 ILO Noise at Work

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Labour Organization

Your health andsafety at work

NOISE AT WORK

Goal of the Module

This Module provides trainees with background information on howoccupational noise exposure can affect a worker's health and safety.Topics discussed include: the health effects of exposure to noise, how tomeasure noise, methods of noise control, and the role of the health andsafety representative in controlling occupational noise.

Objectives

At the end of this Module trainees will be able to:

(1) give several examples of how occupational noise can affecta worker;

(2) suggest several methods of noise control in the workplace;

(3) identify several potential noise hazards in the workplace.

What is in this module


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I. IntroductionII. Health effects of noise exposure

A. Temporary hearing lossB. Permanent hearing loss

C. Other effects

III. Measuring noise

A. DecibelsB. Safe noise levels

IV. Methods of noise control

A. At the sourceB. BarriersC. At the worker

V. Role of the health and safety representative

VI. Summary

Exercise. Case - study on occupational noise

Check - list for controlling occupational noise

I. Introduction

Not all sound is noise noise is sound that people do not like. Noise canbe annoying and it can interfere with your ability to work by causingstress and disturbing your concentration. Noise can cause accidents byinterfering with communication and warning signals. Noise can causechronic health problems. Noise can also cause you to lose your hearing.
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Hearing lossfrom exposure to noise in the workplace is one of the most common of allindustrial diseases. Workers can be exposed to high noise levels inworkplaces as varied as construction industries, foundries and textileindustries. Short-term exposure to excessive (too much) noise can causetemporary hearing loss, lasting from a few seconds to a few days.Exposure to noise over a long period of time can cause permanenthearing loss. Hearing loss that occurs over time is not always easy torecognize and unfortunately, most workers do not realize they are goingdeaf until their hearing is permanently damaged. Industrial noiseexposure can be controlled often for minimal costs and without

technical difficulty. The goal in controlling industrial noise is to eliminateor reduce the noise at the source producing it.

Points to remember

1. Occupational hearing loss is one of the most common of allindustrial diseases.

2. Not all sound is noise noise is unwanted or unpleasant sound.


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3. Noise can cause stress and interfere with concentration. It cancause chronic health problems and it can also cause accidents byinterfering with communication and warning signals.

4. Short-term exposure to excessive noise can cause temporary

hearing loss.

5. Exposure to noise over a longer period of time can causepermanent hearing loss.

II. Health effects of noise exposure

What are the health effects of exposure to too much noise?

The health effects of noise exposure depend on the level of the noise andthe length of the exposure.

A. Temporary hearing loss

After spending a short time in a noisy workplace, you may have noticedthat you cannot hear very well and you have a ringing in your ears. Thiscondition is called temporary threshold shift. The ringing and thefeeling of deafness normally wear off after you have been away from thenoise for a short time. However, the longer you are exposed to the noise,the longer it takes for your hearing to return to normal. After leaving

work, it may take several hours for a worker's ears to recover. This maycause social problems because the worker may find it difficult to hearwhat other people are saying or may want the radio or television onlouder than the rest of the family.


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Suspecthearingloss if a

person

complainsthat he orshe cannothearsomethingwhen youcan.

B. Permanent hearing loss

Eventually, after you have been exposed to excessive noise for too long,your ears do not recover and the hearing loss becomes permanent.

Permanent hearing loss can never be repaired. This type of damage to theear can be caused by long-term exposure to loud noise or, in some cases,by short exposures to very loud noises.

When a worker begins to lose his or her hearing, he or she may first noticethat normal talking or other sounds, such as warning signals, arebecoming unclear. Workers often adapt themselves (get used to) tohearing loss produced by harmful noises at work. For example, they maybegin to read lips as people talk, but have difficulty listening to someonein a crowd or on the telephone. In order to hear the radio or televisionthey may need to turn up the volume so much that it deafens the rest of

the family. Getting used to noise means you are slowly losing yourhearing.


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It isimportantfor youand your

co-workersto beaware ofsigns ofhearingloss.

Hearing tests are the only reliable way to find out whether a worker issuffering from hearing loss. Unfortunately, hearing tests can be difficult toobtain and need to be performed by a trained health-care professional.The reactions of new workers or visitors to a noisy workplace can be

indicators of a noise problem, for example if they have to shout, covertheir ears, or leave in a hurry.

C. Other effects

In addition to hearing loss, exposure to noise in the workplace can cause avariety of other problems, including chronic health problems:

Exposure to noise over a long period of time decreases coordinationand concentration. This increases the chance of accidentshappening.

Noise increases stress, which can lead to a number of healthproblems, including heart, stomach and nervous disorders. Noise issuspected of being one of the causes of heart disease and stomachulcers.

Workers exposed to noise may complain of nervousness, sleepingproblems and fatigue (feeling tired all the time).

Excessive exposure to noise can also reduce job performance andmay cause high rates of absenteeism.


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Maskingnoise

Points to remember aboutthe health effects of noiseexposure

1. Exposure to excessive noise for a short time can cause temporary

hearing loss, while long-term exposure to loud noise, or shortexposures to very loud noises, can cause permanent hearing loss.

2. Workers often adapt themselves to hearing loss produced byharmful noises at work by reading lips as people talk and increasingthe volume on the radio or television.

3. It is important to look for signs of hearing loss in co-workers and tonotice any response new workers or visitors may have to a noisyworkplace - if they shout, cover their ears, or leave in a hurry, itmay indicate a noise problem.

4. Exposure to occupational noise can cause decreased coordinationand concentration which can increase accidents; increased stress,which can lead to heart, stomach and nervous disorders;nervousness; sleeplessness; fatigue; reduced job performance andincreased absenteeism.

5. Exposure to noise over a longer period of time can causepermanent hearing loss.

6. Industrial noise exposure can be controlled.


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III. Measuring noise

Noise in the workplace may be disturbing because of its frequency as wellas its volume. For example, a high-pitched noise, such as a whistle,

irritates the ears much more than a noise with a low pitch, even if thevolume is the same in both cases.

A. Decibels

Sounds have different intensities (loudness). For example, if you shoutat someone instead of whispering, your voice has more energy and cantravel a great distance, therefore it has more intensity (loudness).Intensity is measured in units which are calls decibels (dB) or dB(A). Thedecibel scale is not a typical scale it is a logarithmic scale. Basicallythis means that a small increase in the decibel level is, in reality, a

big increase in the noise level.

For example, if sound is increased by 3 dB at any level, your ears will tellyou that the sound has approximately doubled in volume. Similarly, ifsound is reduced by 3 dB, your ears will feel that the volume has been cutin half. Therefore, an increase of 3 dB from 90 dB to 93 dB means thevolume of the noise has doubled. However, a 10 dB increase at any level(for example, from 80 dB to 90 dB) means the noise intensity hasincreased ten times.

Inside a typical workplace, noise comes from different sources, such astools (machinery and materials handling), compressors, background noise,etc. If you want to identify all of the noise problems in the workplace, thenyou must measure the noise from each source separately. For example, iftwo different sources of noise in a workplace each create 80 dB bythemselves, the level of noise they make together is 83 dB (not 160 dB).Therefore when you consider the amount of noise the two sources maketogether, the level of noise has doubled.

An effective way to measure the noise in your workplace is with a soundmeter. Unfortunately, it can be difficult to get the meters and the trained

personnel to use them. However, there is a simple method that will helpyou to understand if there is a noise problem in your workplace:


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Simple method for assessing noise exposure

Stand at arm's length from a co-worker. If you cannot speak in a normaltone and have to shout to communicate, then the noise level in yourworkplace is too high and should be reduced!

B. Safe noise levels

Is there a safe level of noise?

A safe level of noise basically depends on two things: (1) the level(volume) of the noise; and (2) how long you are exposed to the noise. Thelevel of noise allowed by most countries' noise standards is generally 85-90 dB over an eight-hour workday (although some countries recommendthat noise levels be even lower than this).

Exposure to higher noise levels may be allowed for periods of less thaneight hours of exposure time. For example, workers should not beexposed to noise levels above 95 dB for more than four hours per day.

Exposed workers should be provided with ear protection while exposed atthis level and rotated out of the noise areas after four hours of continuous


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work. Of course before using ear protection and rotation every effortshould be made to reduce noise using engineering controls.

The eight-hour per day exposure limit found in a noise standard is thetotal amount of noise that a worker may be exposed to over an eight-hour

period. The exposure may be from continuous (constant) noise, or fromintermittent noise (noise that is periodic at regular intervals but notcontinuous). Therefore, you must add up the levels of noise you areexposed to throughout the day and see if they exceed 85-90 dB. Note:workers should never be exposed to more than 140 dB ofimpulse noise(usually a very loud noise that occurs only once) at any time.

The following chart gives recommended limits of noise exposure for thenumber of hours exposed.

No. of hours exposed Sound level dB8 90

6 92

4 95

3 97

2 100

1.5 102

1 105

0.5 110

0.25 or less 115

Points to rememberabout measuring noise

1. Noise can be disturbing because of both volume and frequency.

2. Intensity of sound is measured in decibels (dB) or dB(A).

3. A small increase in the decibel level means a big increase in thenoise level.

4. To identify all workplace noise problems, you must measure thenoise from each source separately.

5. An effective way to measure occupational noise is with a sound

meter.


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6. If you cannot get a sound meter and the personnel trained to use it,then use this simple method for assessing noise. Stand at arm'slength from a co-worker. If you cannot speak in a normal tone andhave to shout to communicate, then the noise level in yourworkplace is too high.

7. Safe noise levels take into account: (1) the level of the noise; and(2) the length of time you are exposed to the noise.

8. Generally 85-90 dB over an eight-hour work day is the level of noiseallowed in most standards.

9. Workers who are exposed to high noise levels should be providedwith ear protection and rotated so that they are not exposedfor more than four hours a day. Engineering controls should beused to reduce noise exposure before using ear protection and

rotation.

IV. Methods of noise control

How can noise be controlled?

Workplace noise can be controlled: (1) at the source; (2) through the useof barriers; and (3) at the worker.

A. At the sourceAs with other types of exposures, the best method of prevention is toeliminate the hazard. Therefore controlling noise at its source is the bestmethod of noise control. It can also often be cheaper than other methodsof noise control. This method of control may require that some noisymachinery be replaced. Noise can be controlled at the source by themanufacturer, so that noisy devices never reach your workplace. Manymachines are now required to conform to noise standards. Thereforebefore new machines (such as presses, drills, etc.) are purchased, checksshould be made to see that they conform to noise standards.

Unfortunately, many used machines producing high noise levels (whichhave been replaced with quieter models) are often exported to developingcountries, causing workers to pay the price with hearing loss, stress, etc.


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Put asilencer onthemachine

instead ofear

protectorson theworkers.

Noise control at the source can also be engineered into an existingdevice by making adjustments to parts or a whole machine that reducenoise. For example, the noise level from a pneumatic drill can be reducedby placing a sound-reducing blanket around the drill. A length of tubing onthe exhaust of the drill will also reduce the noise level. A rubber coveringcan be used to reduce noise from metal falling on to metal.

Other engineering methods to reduce noise include:

preventing or reducing impact between machine parts; reducing speeds gently between forward and reverse movements;

replacing metal parts with quieter plastic parts;

enclosing particularly noisy machine parts;

providing mufflers for the air outlets of pneumatic valves;

changing the type of pump in hydraulic systems;

changing to quieter types of fans or placing mufflers in the ducts ofventilation systems;

providing mufflers for electric motors;

providing mufflers for intakes of air compressors.


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Noise -insulatedaircompresso

rs. Theprinciple isthat thenoiseshould becontainedunder thehood. Thehood ismade ofhardmaterialwith asoft,absorbentlining.

1.5 mmstiffened

platereducesvibrations.

Regular maintenance, lubrication and replacement of worn ordefective parts can also be effective ways to reduce noise levels. Noisefrom the way materials are handled can be reduced by measures such

as:


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reducing the dropping height of goods being collected in bins andboxes;

increasing the rigidity of containers receiving impact from goods, ordamping them with damping materials;

using soft rubber or plastic to receive hard impacts;

reducing the speed of conveyor systems;

using belt conveyors rather than the roller type.

A machine vibrating on a hard floor is a common source of noise.Mounting vibrating machines on rubber mats or other damping materialwill reduce the noise problem.

B. Barriers

If it is not possible to control the noise at the source, then it may benecessary to enclose the machine, place sound-reducing barriersbetween the source and the worker, or increase the distancebetween the worker and the source. (However, this can be difficult inmany cases.) The following chart is a simple method of knowing howmuch sound is reduced by distance.

If a smallsound

sourceproduces asoundlevel of 90dB at adistance of1 meter,the soundlevel at a2-meter

distance is84 dB, at 4meters 78dB, etc.

Here are a few points to remember when controlling noise with barriers:

an enclosure should not be in contact with any part of the machine; holes in the enclosure should be minimized;

access doors and holes for wiring and piping should be fitted withrubber gaskets;


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panels of insulating enclosures must be covered inside with sound-absorbent material;

exhausts and air vents must be silenced and directed away fromoperators;

the noise source should be separated from other work areas;

the noise should be deflected away from work areas with a sound-insulating or reflecting barrier;

sound-absorbent materials should be used, if possible, on walls,floors and ceilings.

C. At the worker

Controlling noise at the worker, by using ear protection (sometimes calledhearing protection) is, unfortunately, the most common yet least effectiveform of noise control. Forcing the worker to adapt to the workplace isalways the least desirable form of protection from any hazard. Generallythere are two types of ear protection: earplugs and earmuffs. Both aredesigned to prevent excessive noise from reaching the inner ear.

Earplugs are worn inside the ear and come in a variety of materials,including rubber, plastic, or any material that will fit tightly in the ear.Earplugs are the least desirable type of hearing protection because theydo not provide very effective protection against noise and they can cause

ear infection if pieces of the plug are left in the ear or if a dirty plug isused. Cotton wool should not be used as ear protection.

Earplugsandearmuffs:(1)Formable

wadding-acousticalfibres;(2) Plastic-coveredacousticalfibres;(3)Expandable plastics;

(4)Reusable


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plasticearplugs;(5)Earmuffs.

Earmuffs are more protective than earplugs if they are used correctly.They are worn over the whole ear and protect the ear from noise.Earmuffs are less efficient if they do not fit tightly or if glasses are wornwith them.

Ear protection is the least acceptable method of controlling anoccupational noise problem because:

the noise is still present: it has not been reduced; in hot, humid conditions workers often prefer earplugs (which are

less effective) because earmuffs make the ears sweaty anduncomfortable;

management does not always provide the correct type of earprotection: often it is a case of the cheaper the better;

workers cannot communicate with each other and cannot hearwarning signals;

if ear protection is provided instead of controlling the noise at

source, then management is putting the responsibility on the worker it becomes the worker's fault if he or she becomes deaf.

Points to rememberabout methods of noise control

1. The best method of noise control is at the source. This can be doneby the manufacture, through engineering changes on the sourceitself, through regular maintenance, lubrication and replacement of

parts, or by changing the way materials are handled.

2. Noise can be controlled with barriers by enclosing the source of thenoise, by placing sound-reducing barriers between the worker andthe source, or by increasing the distance between the worker andthe source.

3. The last line of defence is to reduce noise exposure by providingworkers with ear protection, the least effective form of noisecontrol. This method places the responsibility on the worker toprotect his or her hearing.

4. If workers must wear ear protection, then earmuffs are a better


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choice than earplugs. Try to read the packages of various types ofear protectors to find out the level of protection they will provide.Discuss the information with your employer before he or shepurchases the ear protectors. It is important that workers aretrained in the proper use of, and the importance of wearing, theirear protectors.

V. Role of the health and safetyrepresentative

Health andsafetyrepresenta

tive

Your role is to work proactively (this means taking action before there arehealth or hearing problems) to eliminate or control occupational noiseexposure. Controlling noise will help to protect workers' hearing as well astheir overall health. Use the Check-list for controlling occupationalnoise at the end of this Module to help you assess noise controls in yourworkplace. Other steps to help you reach your goals are:

1. Watch for early signs indicating hearing loss. Educate your co-workers so that they also can look for warning signs.

2. Work with your union and the employer to get the noise levels inyour workplace measured. Noise monitoring is an effective way tofind out the precise levels of noise and the sources of noise in theworkplace. (Unfortunately, a sound meter and the trained personnelto use it can be difficult to get. Your local factory inspectorate maybe able to measure the noise at your workplace.)

3. Try to obtain any results of the noise monitoring and compare theresults with your country's noise standards (if they exist).
http://actrav.itcilo.org/actrav-english/telearn/osh/noise/noiseat.htm#Check--listhttp://actrav.itcilo.org/actrav-english/telearn/osh/noise/noiseat.htm#Check--listhttp://actrav.itcilo.org/actrav-english/telearn/osh/noise/noiseat.htm#Check--listhttp://actrav.itcilo.org/actrav-english/telearn/osh/noise/noiseat.htm#Check--list


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4. If your country does not have a noise standard then try to work withyour employer to reach the lowest possible decibel level in theworkplace. Work with your union to put pressure on yourgovernment to develop a noise standard.

5. Conduct the simple method for assessing noise exposure: Stand atarm's length from a co-worker. If you cannot speak in anormal tone and have to shout to communicate, then thenoise level in your workplace is too high and should bereduced.

6. Work with the union and the employer to eliminate noise hazards.

7. Where noise cannot be eliminated, work with the union and theemployer to engineer noise reduction at the source. This may becheaper than buying ear protectors for everyone. If source reduction

is not possible, then barriers should be used. Workers exposed tonoise levels of 95 dB should wear ear protectors and be rotatedafter no more than four hours of continuous work at this noise level.(It is important to make sure employers do not expose workers tonoise levels of 95 dB for more than four hours per day.)

8. Providing workers with ear protection is the least acceptablemethod of noise control. However, if this is the only solution, thenearmuffs are a better choice than earplugs. Try to read thepackages of various types of ear protectors to find out the level ofprotection they will provide. Discuss this information with your

employer before he or she purchases the ear protectors. Workersshould be trained in the proper use of, and the importance ofwearing, their ear protectors. Try to get agreement from theemployer to eliminate noisy machinery by a specified date.

9. If possible, have extra ear protectors available in the workplace toprotect workers in case they forget or lose their own ear protectors.

10. Areas where ear protectors must be worn should be markedclearly, using symbols showing the need for ear protectors. Forthese areas, try to develop non-verbal ways of communicating soworkers can still receive warning signals in case of danger.

11. Pay attention to new workers or visitors their responsesmay indicate that there is a noise problem in your workplace.

12. Conduct a workplace survey asking your co-workers aboutproblems with noise in their work areas. List the various healthproblems that can be caused by noise and ask workers if theyexperience any of these. Information about health problems mayhelp you to identify excessive noise exposures.

13. If possible, try to have regular hearing tests provided for

workers exposed to excessive noise. Some unions have negotiatedhearing tests as part of their collective agreements.


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VI. Summary

Temporary or permanent hearing loss from occupationalnoise exposure is one of the most common of all industrial

diseases. Occupational noise exposure can cause anumber of chronic health problems in addition to hearingloss. However, noise can be controlled by a variety ofmethods, the most effective of which is controlling noise atthe source; the least acceptable method is relying on earprotection.

Generally 85-90 dB over an eight-hour workday is theallowable level of noise, although it is better to reducenoise even further, whenever possible. There are anumber of steps you and your union can take towards

controlling noise in your workplace.

Exercise. Case-study on occupational noise

Note to the instructor

You will need to provide each trainee, or each group of trainees,with a copy of the case - studies. If you cannot make copies,then read the case - studies out loud to the group and discuss.Trainees should work in small groups of three to five people.

Instructions

Each group should read the cases and then answer thequestions. Discuss group answers with the whole group.

The following case - studies are based on real situations.

Case 1

The problem

Company XYZ is a manufacturer with five power pressesproducing noise levels of 102 - 104 dB. Even when only one ortwo presses are operating, the noise levels are still as high as 98dB. This is painful for the workers and puts them in seriousdanger of losing their hearing.

Question

(1) What solutions to this problem can you suggest?


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How the problem was solved

To solve the problem, the power presses were moved to adistance of 20 metres from the place where most of the workers

were located. In this way, the workers were exposed toacceptable noise levels of 75-80 dB. Workers who operated thepower presses were provided with earmuffs and rotated to aquieter section of the factory after a maximum of four hours'continuous work in the power press area.

Questions

(1) Were these actions good solutions to the problem? Why orwhy not?

(2) Are workers safe if they are exposed to excessive noise foronly four hours?

(3) Do you think there was still noise exposure for the workerseven after the changes were made?

(4) Can you think of any better solutions to the problem?

(5) Why are earmuffs not an acceptable solution to noiseexposure?

Case 2

The problem

Company ABC produces nails. The machines that cut the nailsproduce a noise level of 95 dB. These machines are all in a rowin one section of the factory and need to be operated by aworker for eight hours a day. All workers have been given earprotectors but they do not wear them because it is too hot anduncomfortable.

Question

(1) What solutions to this problem can you suggest?

How the problem was solved

The union and the employer discussed the noise problem anddecided that enclosing the nail-cutting machines would cost lessthan buying ear protectors for all of the workers. Inexpensive,

local materials were used to build a full enclosure around themachines. The enclosure reached from the floor to the ceiling,


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with no holes except the door to enter the machine area. Theenclosure reduced the noise level outside the machine area to85 dB. Workers operating the nail-cutting machines wererequired to wear earmuffs and were also rotated out of that area

after four hours of continuous work there. A sign was placed onthe door to the enclosed area reminding workers to put on theirearmuffs before entering the noisy area.

Questions

(1) Were these actions good solutions to the problem? Why orwhy not?

(2) Why were the workers rotated out of the enclosed area after

four hours of continuous work there?

(3) Can you think of any better solutions to the problem?

(4) Are the solutions to this case better than the solutions thatwere used for the first case? Why or why not?

Points for discussion

1. Can you think of an example from your own workplace whereexcessive exposure to noise has been controlled? If so, describe tothe group how it was controlled.

2. Can you think of an example from your workplace where a noiseproblem has not been controlled?

3. Discuss the situation with the group and try to come up with somepossible solutions together.

Action planfor controlling occupational noise in yourworkplace


Give each trainee a copy of the following action plan to use in his or herown workplace.

Action plan


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Develop an action plan to help you address any problem(s) with noise inyour workplace.

1. Describe the problem.

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2. How can the problem be solved?

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3. What steps can your union take to solve the problem?

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4. What steps should your employer take to solve the problem?

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5. What will you do about this problem when you return to yourworkplace?

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Check-list for controlling occupational noise


Give each trainee a copy of this check-list to use in his or herown workplace. Relate it to the action plan as far as possible.

Instructions for using this check-list

Use this workplace check-list as a guide for assessing noisecontrols in your workplace.

YES

NO

1. Are noisy parts or machines enclosed or covered completely?

2. Are machines serviced regularly to avoid increased noise?

3. Are sound-absorbing materials used on the ceiling, walls, or

machine covers?

4. Are noisy equipment and noisy parts replaced with quietermodels?

5. Are adequate barriers used to prevent noise from spreading?

6. Has the dropping height been reduced for goods being collectedin bins and boxes?

7. Are people working with quieter machines protected from noiseproduced by other machines?

8. Are workers in noisy work areas rotated to avoid long hours ofexposure?

9. Are earmuffs or earplugs used where the noise level reaches orexceeds 85-90 dB?

ILO Noise at Work

Documents

Transcript of ILO Noise at Work