Noise and vibration in the workplace

Noise and vibration in the workplace have a high potential to produce serious effects on the health of workers. Every day, millions of workers are exposed to noise and vibration in their workplace. There is a growing concern among occupational health and safety professionals, muniriyathse (safety zone) will describe one by one in detail the Introduction to noise and vibration, Noise and vibration hazards and what is vibration and noise control.

 More frequently, new tools appear that make our day-to-day work easier, but they can have other effects on our health. We forget the new layer of risk. We could continue to enjoy our comfort in the workplace with complete safety, we must identify the potential hazards and establish some preventive measures regarding noise and vibration.

Noise and vibration in the workplace means

Noise and vibration in the workplace can be a serious health and safety hazard. Long-term noise exposure can lead to hearing loss, while vibration can lead to a variety of health problems, including hand-arm vibration syndrome (HAVS) and whole-body vibration syndrome (WBVS).

Noise is defined as unwanted sound. It is measured in decibels (dB). The average person can comfortably hear sounds up to 85 dB. However, exposure to noise levels above 85 dB can cause hearing loss over time.

Vibration is defined as the oscillating motion of a body. The average person can comfortably feel vibrations up to 5 m/s². However, exposure to vibration levels above 5 m/s² can cause a variety of health problems, including HAVS and WBVS.

What is noise?

There is no unequivocal definition, but it could be said that noise is an unwanted sound that can be considered annoying, unpleasant useless for the person who hears it. We understand noise as an inarticulate and confused sound, more or less loud. Some types of sounds are considered pleasant (exceptional) depending on the situation or the specific sensitivity of people such as DJ sound.

The propagation of sound in air is comparable to that of waves in water. When we throw a stone on a raft, circular waves appear that spread evenly in all directions. Sound in the air, these invisible waves propagate in the same way, transmitting part of the energy emitted by the sound source to people.

Sound is an auditory sensation that originates from an acoustic wave from a vibration that propagates in an elastic medium. Vibration is produced by energy, for example, that is generated when a guitar string is pressed. 

Frequency and unit of sound

The perceived energy will depend on the distance we are from the noise source. The less distance, the more energy is perceived. Sound is characterized by frequency and intensity. The frequency tells us how the sound is, acute or chronic, and the intensity informs us of the quantity, that is, the volume. The noise, considering the different frequencies, is measured in decibels A.

The frequency of sound is defined as the number of times the sound wave acquires the same value per unit of time. It is expressed in cycles, Hertz (Hz). The frequency determines the pitch of the sound. Bass or low-frequency sounds are those that are repeated a little in time (a few cycles per second), such as thunder or a truck horn.

High-pitched or high-frequency sounds are repeated more in time, for example, that produced by a whistle. The human ear is capable of perceiving sounds with frequencies between 20 and 20,000 Hz. 

The intensity corresponds to the strength of the vibration, of the alteration that occurs in the air. It is measured in decibels (dB). The human ear is capable of perceiving between 0 dB of the threshold of hearing and 140 dB of the threshold of pain.

dB	Sound
50 – 60	Normal conversation
65 – 75	Loud conversation
90 – 100	7G grinder sound
140	Taking off of the aircraft sound

Noise hazard effect

To determine the effects on the health of workers, the intensity and frequency of the noise and the exposure time must be considered. Current legislation recognizes hearing loss or deafness caused by noise at work as an occupational disease.

Now, noises are so integrated into everyday life especially in the workplace, that we often consider them natural and unavoidable. When we have the feeling that we have gotten used to noise and that it no longer bothers us, it is when it can be more dangerous because we have surely already lost hearing. 

Noise-induced hearing loss (NIHL)

Exposure to high levels of noise can cause temporary loss of hearing capacity, an effect known as auditory fatigue which is recovered with sound rest when no nerve damage has occurred auditory. 

If noise exposure has been high in intensity and time or there has been prolonged fatigue without recovery time, hearing loss or permanent hearing loss can occur. On the other hand, short-term exposure to very loud noise, such as an explosion, can cause the eardrum to rupture. This exposure can cause permanent hearing loss.

It also often interacts with other risk factors and increases the danger to which workers are exposed. For example, if the worker does not hear an emergency alarm can be fatal.

Tinnitus

Ringing in the ear due to repeated exposure to high noise. Research shows that exposure to certain chemicals, and substances that contain ototoxic products, such as certain pesticides, solvents and drugs, can hurt the functioning of the ear, which can cause hearing loss. 

The risk of hearing loss is increased when workers are exposed to chemicals while working in environments with high noise levels. This combination often causes hearing loss, which can be temporary or permanent, depending on the noise level, the dose of the chemical, and the length of exposure.

Another health effect

Continuous noise exposure can cause, in addition to changes in heart rate and breathing, and can also influence the endocrine and nervous systems. Similarly, the fact of working in a noisy environment can alter sleep, cause tiredness, irritability, headache and nausea, and in some cases affect mental health since it sometimes causes symptoms of anxiety and increases discomfort and stress. It also negatively affects our relationship with others and the environment, for example, creating misunderstandings in a conversation. 

Control measures

The OSHA standard on exposure to occupational noise, described in 29 CFR 1910.95, only requires audiometric tests at the level of noise action (that is, a weighted average of 85 decibels in 8 hours). However, using hearing protection and using audiometric tests to detect early signs of hearing loss. 

Loud noise at work can damage hearing. Approximately 22 million American workers are exposed to hazardous noise on the job. To minimize occupational noise-induced hearing loss, the National Institute for Occupational Safety and Health (NIOSH) recommends that workers not be exposed to a noise level that exceeds 85 decibels (dB A) for 8 hours. To create a healthier workplace, NIOSH recommends a hierarchy of control approach.

Permissible noise exposure limit
Per day/hour	dB A
8	85
6	90
4	95
2	100
1	105
30 minutes	110

Use of the Hierarchy of Control

Occupational safety and health professionals use the hierarchy of control to determine how to implement effective controls. This approach groups actions by their potential effectiveness in reducing or eliminating the noise hazard. It is important to assess the risks of noise and vibration in the workplace and to take steps to control these risks. By doing so, you can help to protect your employees from injury and illness.

1. Elimination: In most cases, the preferred approach is to remove the source of the hazardous noise. If possible, the source of the noise or vibration should be eliminated. For example, if the noise is coming from a machine, the machine could be redesigned to be quieter.
2. Substitution: When elimination is not possible, replacing noisy equipment with less noisy equipment may be the next best thing to protect workers from high noise hazards is called substitution.
3. Engineering control: hazardous noise cannot be controlled by removing the source or substituting, engineering controls can be adopted to reduce the noise to safer levels. Engineering controls require physical changes to the workplace, such as redesigning equipment, maintenance, damping, silencing etc. to eliminate sources of noise and barriers to prevent noise from reaching the worker.
4. Administrative control: If the hazard cannot be eliminated through elimination, substitution, or engineering controls, the next step is to reduce noise exposure through the use of administrative controls. For example, an employer may change an employee’s work schedule to avoid too much noise, training and awareness etc.
5. Personal protective equipment (PPE): such as earplugs or other hearing protection devices, is the last option in the hierarchy of control. PPE is generally less effective than elimination, substitution, and engineering controls because they rely on human behaviour.
6. Isolating the hazard: If the source of the noise or vibration cannot be eliminated, it can be isolated from the workers. This can be done by installing soundproofing or vibration-damping materials.
7. Reducing the exposure: If the hazard cannot be eliminated or isolated, the exposure to the workers can be reduced. This can be done by reducing the amount of time that workers are exposed to noise or vibration, or by providing them with personal protective equipment (PPE).

Training

Receive information and training about high noise exposure hazards and control measures (in a language and with a vocabulary that they understand) about the dangers in the workplace. NIOSH encourages occupational safety and health professionals, employers, and workers to obtain more information and training about controls for exposure to high noise.

Consult a workplace safety and health professional to establish the training program for your work environment and noise exposure. 

Review the records of injury and work-related diseases.

Industrial noise injury begins with hearing loss due to acute frequencies between 4,000 Hz and 6,000 Hz. Noise has been recognized as one of the physical agents capable of negatively influencing the health of pregnant workers and the fetus.

The main risk affects the fetus since prolonged exposure can cause hearing damage. According to the criteria of prestigious pediatric associations, above 80 dB the woman, from the 20-22 weeks of pregnancy, should leave that work environment.

Occupational safety and health professionals and employers can take the following steps to reduce noise in the workplace. Consider these solutions when creating your hearing loss prevention program: 

• Routinely maintain tools and equipment (such as lubricating gears)
• Reduce vibration where possible
• Isolate the noise source in an isolated room or enclosure
• Put a barrier between the noise source and the employee.
• Isolate the employee from the source in a room or booth (such as a sound wall or windows)
• Enforce wearing hearing protection such as an ear plug or muff

Vibration

It is increasingly common to find work that exposes people to vibrations, excessive exposure to vibration causes moderate to serious health risks such as Hand-Arm vibration syndrome and also whole–body vibration. Vibration is more and less similar to noise. Vibration is the oscillatory motion of an object rising to occupational health effects.

Whole-body Vibration

Mechanical vibrations are undulating movements transmitted to the body. Depending on their intensity and the area of incidence, they can cause injuries and disorders to workers.

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According to the ILO, mechanical vibrations are movements transmitted to the body by structures capable of producing harmful effects or discomforts on the worker. This movement generates energy that the body absorbs. Depending on its intensity and incidence zone, vibrations can cause lesions and disorders.

They are global and therefore affect the entire organism. They are produced by vehicles, machines or platforms. These vibrations can produce:

• Lumbar and abdominal pain. 
• Degenerative changes, spinal injuries and degeneration of intervertebral discs.
• Other effects such as digestive problems, urinary difficulties, visual disturbances, balance problems, lack of sleep, and delayed reaction time…

Hand-arm Vibration

HAVS is a condition that affects the hands and arms. It is caused by long-term exposure to vibration from tools and machinery. Symptoms of HAVS include numbness, tingling, and pain in the hands and arms. In severe cases, HAVS can lead to permanent disability. Vibrations emitted by tools or work equipment such as drills, brushes, cutters, chiselling or hammering for example. The effects they cause are:

• Vascular disorders, pale fingers… 
• Bone and joint disorders, mainly deformities.
• Neurological disorders. 
• Muscular disorders, muscular atrophy…
• White finger

Vibration exposure standards

Taking into account the frequency of vibration, the following types can be distinguished:

The frequency refers to the number of times that the element vibrates per second. It is measured in Hertz (Hz). In general, machines do not register an exact frequency but usually, mix several.

1. Very low frequency (less than 1 Hz): They are usually produced using transport such as ships, aeroplanes or trains. It is a vibration that can cause dizziness and vomiting. They affect the central nervous system.
2. Low frequency (from 1 to 20 Hz): They are related to the use of machinery dedicated to industrial activities such as the management of excavators, rollers, tractors, the conduction of some trucks and lifting wheelbarrows…Among its consequences are vision disorders, low back pain and hernias caused by the use of construction machinery.
3. High frequency (from 20 to 1000 Hz): They are generated by the oscillation of manual tools that are concentrated in the hand-jack system. These machines cover a great variety and a cropped, drilling, pneumatic hammer, hydraulic mountain range…can cause musculoskeletal disorders, osteoarthritis and wrist injuries or cramps.

Vibration control measures

Vibrations are considered a risk factor for the health of workers who are exposed to them. So appropriate preventive measures must be taken to mitigate them. It will be the obligation of the employer to evaluate this risk and, if necessary, the measurement of the levels of mechanical vibrations to which the workers are exposed.

Verify that it does not exceed the limits set. Similarly, workers must be informed and trained about the possible risks in their workplace. 

 Whole-body vibration

WBVS is a condition that affects the whole body. It is caused by long-term exposure to vibration from vehicles and machinery. Symptoms of WBVS include fatigue, headache, and back pain. In severe cases, WBVS can lead to permanent disability. In the absence of formal regulations, use the Threshold Limit Values ​​(TLVs) and guidelines recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). The following precautions help reduce exposure to whole-body vibration:

• Limit the time workers spend on a vibrating surface.
• Isolate the vibrating source to reduce exposure.
• Make sure the equipment is well maintained to avoid excessive vibration.
• Install vibration-damping seats.

Hand-Arm vibration

The American Conference of Governmental Industrial Hygienists (ACGIH) has developed Threshold Limit Values ​​(TLVs) for hand and arm vibration exposure. The vibration can be reduced by eliminating the source, substituting the source, changing work techniques and maintaining. 

Safe work practices

Along with the use of anti-vibration tools and gloves, workers can reduce the risk of hand-arm vibration syndrome (HAVS) by following work practices:

• Use a minimum-force hand grip that still allows the safe operation of the tool or process.
• Wear enough clothing, including gloves, to keep warm.
• Avoid continued exposure by taking rest periods.
• Do not use defective tools. Worn, dull or misaligned tools will vibrate more.
• See a doctor at the first sign of vibration sickness and ask about changing to a job with less exposure.

Remember, it is important to correctly attend to preventive measures, as this way we will avoid harmful consequences for our health in the short and long term.

1. Organizational measures: they are focused on decreasing the worker’s exposure time to mechanical vibrations by changing schedules, the organization of tasks, and rest periods.
2. Measures on source: It is about choosing tools that generate a lower level of vibrations.
3. Measures on the worker: refers to the use of individual protection equipment (EPI) not only to protect from vibrations but also from the rest of the conditions that can affect employee safety (cold, moisture …). 

Training

Training programs are an effective means of increasing awareness of HAVS in the workplace. Training should include the proper use and maintenance of vibrating tools to prevent unnecessary exposure to vibration. Vibrating machines and equipment often make a loud noise as well. Therefore, vibration control training and education should also address noise control concerns. 

The adoption of preventive technical measures for vibrations would be:

If it is not possible to avoid vibrations at work, there is a legal duty of the company to assess the risks and establish preventive measures. Thus, in the organization, all work or processes that include vibrations must be carefully analyzed to determine if it is possible to eliminate them, reduce them or prevent workers from being exposed for prolonged periods.

• Provide the machines with shock absorbers.
• If possible, use non-vibrating tools.
• Use means of personal protection such as anti-vibration gloves.
• Fix the machines well to their base to avoid unnecessary movements.
• Perform periodic maintenance of machines.
• Immediately report machine malfunctions.
• Limit the time of exposure to vibrations.
• Take 10-minute breaks for every hour of work in vibrating conditions.
• Alternate work with other tools that do not have vibrations.
• It is convenient to carry out a specific annual medical examination to know the affected state of the people. 
• Job rotation. 

Conclusion

Here are some additional tips for controlling noise and vibration in the workplace:

• Regularly inspect machinery and equipment for signs of wear and tear. This will help to identify potential noise and vibration hazards before they cause problems.
• Provide training to employees on the risks of noise and vibration and how to protect themselves. This will help employees to take steps to reduce their exposure to noise and vibration.
• Monitor noise and vibration levels in the workplace. This will help you to track the effectiveness of your control measures and identify any areas where further action is needed.

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