Industrial Hygiene – Noise Essay

Industrial Hygiene – Noise Essay

Noise is defined as sound which is generally loud, unwanted and not pleasant. In some settings, noise is unexpected and hard to control (Bronzaft, 1996).  It is persistent not only in metropolitan and congested areas but more importantly in industrial facilities.  

The unit of noise level, decibel (dB), is measured in a logarithmic scale (Dawson, 2005).  This means that a small numeric increase indicates a huge increase in the intensity.  For example, a whisper would measure 20 dB while a thunder averages 110-120 dB on the scale.

Industrialization has consequently led to a considerable noise level intensification in industrial sites to a point that noise is regarded as a probable health risk (Prasanth and Sridhar, 2008).  Although the obvious harmful effect of noise is on the hearing capacity of a person, numerous studies have already pointed out that noise not only has physiological impact on an exposed person but psychological effects as well.  Noise was shown to have harmful effects that include hearing damage, sleeping disorder and even effects on cardiovascular functions and on fetal growth (Babisch, 2005).

Noise intensities and rates of occurrence vary in different manufacturing environments engaging in numerous machine processes.  This results to varied effects on exposed workers based on how close they work with the machineries and how long and how often they are in such a situation.  An additional factor is the varying sensitivity of workers to the noise hazard that is involved. This could result to various behaviors or outlooks of the exposed workers (Arezes and Miguel, 2006).  It is important in the field of Industrial Hygiene that the above factors are taken into consideration when putting up a hearing conservation program.  It is not only imperative that noise levels are decreased to the lowest level possible but also to understand the human dynamics behind so that programs on hearing conservation are implemented effectively.


The data and analysis presented in this paper are based on literature research.  Several research databases were utilized to gather results of studies on the effects of noise and the existing guidelines on noise exposure controls.  Sources include journals, books and newspaper articles.  A significant amount of time was spent on reviewing the results presented on research studies and their implication on Industrial Hygiene.  A review of some case studies and documented noise-related incidents was also undertaken.  The research focused on noise and it’s impact on industrial workers’ well being.

Findings and Results

Several studies have already shown the most obvious effect of noise on hearing.  Noise results to severe mechanical injury to the inner ear’s hair cells (in the cochlea) when the interim sound strength level is very high (>120 dB).  Even long term exposure to sound strength averaging at > 85 dB is likely to lead to considerable loss of hearing because of metabolic fatigue.  The World Health Organization has deemed a daily mean sound level of 70 dB as safe and not damaging to the ear (Babisch, 2002).  Being exposed to a sound level of 85 dB and higher may lead to deafness if long-term daily exposure is for eight hours. A noise level of 70 dB would be similar to the sound coming from a vacuum cleaner while the sound coming from an alarm clock would average at 80 dB.  Garbage trucks and rock concerts would average around the 80 to 100 dB range. Approximately twenty million Americans are exposed frequently to unsafe noise levels and ten million have developed impaired hearing due to unsafe sound.

Still, noise levels within the safe limits can have non-auditory complications if they continually impede with sleep and other recreational pursuits, interrupt with the clarity of speech and communication, or disrupt attention in activities requiring complete focus.

Table 1 outlines the allowable daily exposure time without hearing protection at different decibel levels as set out by the Occupational Safety and Health Administration (OSHA).


Table 1

Allowable Daily Exposure Time without Hearing Protection

dB Level Hours Per Day
90 8
92 6
95 4
97 3
100 2
102 1.5
105 1
110 0.5
115 0.25

Source: OSHA (Bronzaft, 1996)


More studies have now established relationships between noise and health effects other than direct hearing loss or damage.  Noise does not only harm the ear but it also has psychological and physiological effects as well. Physiological effects of unsafe noise levels take the form of either stress or arousal.  Such response includes severe hypertension, heat rate increase, blood cholesterol level increase and extreme hormone secretion. Definite injury to any susceptible system of the body (e.g. cardiovascular) can occur if these bodily responses are sustained because of chronic noise existence.  In some laboratory experiments, noise has resulted to embryo damage and lower fertility in rats (Bronzaft, 1996).

Noise also has its own share of psychological effects which include sleeping disorder and changes in behavior of an exposed person.  A deprivation of sleep can be a factor to a greater risk in industrial accidents and injuries. It has been found that a person who works in an environment with high noise levels or is sleep-deprived due to noise is inclined to make more mistakes, erroneous judgment, develops violent behavior, gets easily irritated, unfriendly, cold, easily burns out, careless, selfish and unsupportive.  That person may also have issues with concentration, may develop a picture of losing control over his surroundings and in the worst case, may become depressive. An example of aggression is the dispute between neighbors due to a loud television or stereo which is often reported in the media to have resulted to an altercation and even killings.  In noisy metropolitan areas, people most of the time do not lend a hand to people asking for help and would instead keep on walking ahead (Bronzaft, 1996).

A study by Melamed et al. (1997) investigated the relationship between noise and cardiovascular risks by measuring serum lipid and lipoprotein levels in blue-collar workers.  Previous researches have associated a rise in serum lipid levels as a cause in the hardening or furring of the heart’s arteries. The study kept under control other unfavorable conditions like physically demanding tasks, shift schedules and job monotony. Another factor considered are the workers’ different levels of noise sensitivity that would indicate how they appraise the ambient noise whether as unwanted, exasperating or distressing. This was based from previous studies in the industrial sector where it has been shown that employees who are annoyed by noise have considerably exhibited additional responses from stress as compared to employees unbothered by noise.  The study had a large sample size and covered both male and female workers.  The results showed that being exposed to high noise levels in the industrial sector is linked to higher levels of serum lipid especially for younger male workers.  The study also established that both male and female workers who exhibit noise annoyance have considerably higher levels of serum lipid.

Another study investigated the effects of repeated noise exposure on resting heart rate and blood pressure.  A large sample of male and female workers at 21 manufacturing facilities in Israel was measured with their resting heart rate and blood pressure at the start and end of the working day.  Different industrial sectors were represented including electronics, food, metal and others.  Most of the study population (70%) was production staff and managers were the remaining 30%.  Additional personal information were collected for the study population that included personal routines, medical records, whether they use devices for hearing-protection, length of time in existing work assignment and workstation, and consumption of alcohol and coffee.  The noise source was also characterized as to its frequency of occurrence (constant or sporadic) and the source location (from own workstation or from other departments).  The results showed that ambient noise in industrial environments acutely affects resting heart rate and that the effect amplifies with the duration of the noise exposure (Kristal-Boneh et al., 1995).

A separate study in an automobile assembly environment showed that industrial noise exposure of automobile workers has chronic and not transitory effects on the properties of the circulatory system and boosts the occurrence of hypertension as well (Chang et al., 2007).  The researchers divided the sample population into two groups with one in a high noise level exposed environment and the other in a low noise level working surroundings.  Vascular parameters were measured in each individual in 24-hour timeframe to include work period and sleep. Noise level in this study was at 79-110 dB and manufacturing processes for the high noise environment included forging, body and engine assemblies and trial tests on roller and track.  The sample group representing the low noise environment was office employees located in a separate building.

The aforementioned studies, as well as other studies, have provided scientific evidence of the physiological and psychological effects of noise to workers in industrial environments. Health issues also abound in communities affected by loud sounds coming not only from manufacturing facilities but also recreational activities like video game arcades and rock concerts that it is now classified as a pollutant.  Unlike chemical pollution where dangerous substances are emitted into the environment or water pollutants that kill corals and requires years to recover, noise pollution is regarded as a “local” issue (Schudel and Benz, 2009).  Noise pollution usually affects specific groups of people like a manufacturing facility or a local community.  This makes addressing the issue of noise more manageable and relatively easier to accomplish as compared to the other types of pollution.

It is imperative that in implementing a Hearing Conservation Program that various factors have to be considered to make it effective.  The use of newer technologies, availability and use of hearing protection devices, training and awareness and administrative improvements are essential elements to make the program work.

Technology has been employed for noise cancellation which allowed for battery-operated head sets that has the capability to cancel out unwanted frequencies.  The hearing protection devices themselves have also evolved the past years with more ergonomic and user-friendly designs. These devices now have enormous and multicolored varieties of muffs, bands, earplugs, and combo units for various applications. But as a precaution, earplugs are only effective if fitted properly by entirely blocking the ear canal (Brown, 1997).

Encouraging employees to use the hearing protection devices takes more than having the newest devices available. It requires a change in behavior or attitude of workers towards noise.  Studies by Arezes and Miguel (2005 and 2006) have shown that workers working in the same workstation and exposed to the same sound source and intensity have varying assessment of the risks that are involved with their exposure to the noise.  These differences lead to various behaviors or attitudes towards the use of hearing protection devices. Risk recognition, therefore, should be a vital part in formulating and implementing a Hearing Conservation Program, especially in training the workers.

In starting a Hearing Conservation Program, it is recommended that an assessment of the workplace is carried out including a job analysis and should be correctly documented if one has not been done yet. The assessment is a source for baseline information of tasks and the required Personal Protective Equipment including for hearing protection. Be aware of job tasks, which are potential noise sources, and tasks that are not frequently carried out (Johnson, 2006).

When developing a Hearing Conservation Program, document the elements in the form of a written program manual or procedure.  Regularly audit the program and the available Personal Protective Equipment. Review the program manual and revise for changes at least annually or if conditions have been modified that requires a program update. The program team should include representatives for workers, compensation and insurance and the health and safety committee to guarantee that everything is covered. Program records should be current, open and accessible for all workers to review.  One good audit activity is to spot-check with workers and pose questions that would gauge their level of awareness of the program.  Questions can include how to use and dispose of hearing protection devices.  This facilitates interaction and serves as a way of knowing what the weaker aspects of the program are. Temporary and contractual workers should also be included in these audits.

Employee involvement is also beneficial for the program.  Workers are the ones who deal every daily with the tasks and know first hand what aspects of the job work and not work.  Solicit ideas on what enhancements can be made like training needs and methodology, improved protection devices (like more size or material selection).  In the case of personal protection equipment, it is not all the time that the most expensive works the best.

Training plays a vital role in communicating and developing the desired behavior on hearing protection in the workplace. As such, a dynamic training plan should be put in place which puts into consideration factors like shift schedules, length and schedule of training with a proper documentation system in place. Awareness of the program should also extend to temporary and contractual workers, visitors and guests.  Realistic and illustrative examples are very useful for training and awareness (Johnson, 2006).  Hearing loss is a serious issue and this must be conveyed in the most effective way possible. Include situations in the local workplace that can generate prospective injury in training examples.  Training should be comprehensible to everyone especially in workplaces where multiple languages are being used.  Test for the level of comprehension of the training attendees to verify which aspects of the training modules need improvement.  Confirm that the important points that have to be conveyed has been learned or assimilated by the employees.  Documentation of employee training attendance is very important for reference and should be filed in such a way that it is easy to retrieve and refer to.

It is crucial that hearing protection program is updated after it was launched if changes in conditions or requirements occur.  Elements of the training module that were not effective or did not work should be taken out.  Keep current with changes and improve on trainer’s skills also.  Workers should realize through the program that hearing protection is a personal responsibility and not just an employer’s initiative.

It is also imperative that when developing an organization’s hearing protection program that the impact of its activities to the surrounding community with regards to noise pollution should also be considered. Noise pollution abatement is part of most national and local environmental laws and regulations.  Noise assessment is a common requirement in obtaining a certificate of approval for air emissions.  Companies without a working hearing protection program will find themselves in trouble if they fail to meet the requirements of these legislations.  A number of companies have already been penalized for violating these environmental regulations due to noise pollution.

A blasting company in Karratha, Australia was fined $2,000 for being the source of high noise levels at its mining operations (ABC Regional News Australia, 2005).  They were ordered to lower the possibility of additional pollution.  Noise coming from another Australian company dealing with industrial timber has caused the State Government to offer compensation to landowners affected by the noise pollution (ABC Regional News Australia, 2005).

In Quebec, Canada’s Supreme Court upheld the $15-million fine for a cement company resulting from a class action lawsuit filed by approximately 2,000 residents who were affected by dust, noise and other pollution from the cement plant’s operations (Leger, 2008).  This was considered as a landmark victory since although the cement company has met its requirements under applicable environmental regulations, the High Court recognizes that affected parties have the right to claim damages in situations were the impacts of pollution are extreme and unwarranted.  This ruling was based on a Quebec Civil Code provision that affirms that affected residents do not have to undergo aggravations that exceeds the limit of forbearance.

The above cases have significant implications on how manufacturing firms operate and their responsibility on noise abatement not only to their own employees but also to the surrounding community that are disturbed by noise pollution from the company’s operations.


Numerous studies have already established the correlation between noise pollution and its health effects to humans.  Sound at unsafe decibel levels has a wide-ranging effect on people both physiologically and psychologically.  Noise does not only lead to ear damage but is deemed as a risk to a person’s overall well being. Health effects on people can be chronic and/or acute depending on how frequent and how close the person is to the source of noise.

The field of Industrial Hygiene plays an important role in noise abatement and protection.  From a macroscopic level, Industrial Hygienists could be advocates so that environmental and health policies identify adequate standards for noise levels in which the entire range from personal welfare to somatic health is being considered.  At the organizational level, Industrial Hygiene principles can be applied and influence the creation of a Hearing Conservation Program that is developed, implemented and monitored with the protection of workers in mind.

Each work setting is distinctive and its sound levels can be potential sources of high levels of noise.  Having a proactive Noise Conservation Program helps workers safeguard their hearing while performing their tasks.  Provision of hearing protection devices and adequate training and awareness makes workers comprehend that exposure to noise is a hazard in and outside of work. Doing these and other initiatives not only reduce the company’s liability but more importantly, it protects the company’s most valuable asset – the employees.  Hearing loss should not be taken lightly because once hearing damage has taken place; it can never be restored again.



ABC Regional News Australia (2005, August 15). Mining company fined for noise pollution. Australian Broadcasting Corporation.

ABC Regional News Australia (2005, August 31). LandCorp promises compensation for noise pollution. Australian Broadcasting Corporation.

Arezes, P.M. & Miguel, A.S. (2006). Does risk recognition affect workers’ hearing protection utilisation rate? International Journal of Industrial Ergonomics, 36(12), 1037-1044.

Arezes, P.M. & Miguel, A.S. (2005). Individual perception of noise exposure and hearing protection in industry. Human Factors, 47(4), 683-692.

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Brown, E.W. (1997). What can we do about noise pollution? Medical Update, 20, 4.

Chang, T.Y., Su, T.C., Lin, S.Y., Jain, R.M. & Chan, C.C. (2007). Effects of occupational noise exposure on 24-hour ambulatory vascular properties in male workers. Environmental Health Perspectives, 115(11), 1660-1664.

Dawson, D. (2005). The problem of noise and the solution of sound? Intensive and Critical Care Nursing, 21(4), 197-198.

Johnson, L.F. (2006). The everyday hearing protection program. Occupational Health & Safety, 75(4), 32.

Kristal-Boneh, E., Melamed, S., Harari, G., & Green, M.S. (1995)

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