1 Department of Otorhinolaryngology, Muhimbili University of Health and Allied Sciences, Tanzania
2 Department of Otorhinolaryngology, Muhimbili National Hospital, Tanzania
Submission:April 28, 2022;Published:May 16, 2022
*Corresponding author: Massawe ER, Department of Otorhinolaryngology, School of Medicine, Muhimbili University of Health and Allied Sciences, Tanzania
How to cite this article: Massawe E, Mawala S, Ntunaguzi D, Kishevo P, Bweli M. Knowledge, Attitude and Practices on Prevention of Noise
Induced Hearing Loss Among Factory Workers in Tanzania. Glob J Oto, 2022; 25 (2): 556156. DOI: 10.19080/GJO.2022.25.556156
Background: Noise-induced hearing loss (NIHL) is sensory deafness caused by long-term exposure of the auditory system to a noisy environment. The pathogenesis of noise-induced hearing loss is complex. Various theories try to explain this, such as the oxidative stress theory, but none perfectly explains the occurrence of noise-induced hearing loss. There is no treatment which can completely reverse the damage. More research is required to explore the pathogenesis and to better guide clinical practice. Preventative strategies, such as educating the public about hearing health, should be adopted to reduce the harm of noise-induced hearing loss [1-3].
Objective: The main objectives were to explore the knowledge, attitudes and practices among factory workers in Ilala regarding noise induced hearing loss and the use of hearing protective devices in NIHL prevention. Noise induced hearing loss is a well-known entity in daily practice of Otorhinolaryngology (ORL).
Methodology: A descriptive cross-sectional design was used to assess knowledge, attitude, practices among factory workers. A study was conducted in Cement Factory and minor factories in, Dar Es Salaam, Tanzania. Non-probability convenience sampling technique was used to obtain all 185 participants. The data was collected using Kiswahili questionnaire with close ended questions. All participants were consented before participating in study, and all the responses were coded and entered in a computer software programme statistical package of social sciences (SPSS) for data analysis.
Results: Large proportion of participants were males (79.5%), aged 26-35years old (34.6%) and with primary education (48.6%). 70.3% were aware of NIHL their main source of information being their teammates. Level of knowledge were 49.2% 40.8% and 10.0% for high, moderate and low levels respectively. Knowledge was influenced by gender and working experience. 84.6% had good attitude on prevention of NIHL which was largely influenced by education level. Only 19.2% had good practice on prevention of NIHL.
Conclusion: There is still a problem among factory workers to practice prevention of noise induced hearing loss despite of knowledge they have
Abbreviations: ACC: Accident Compensation Cooperation; CDC: Centres for Diseases Control and Prevention; dB: Decibels; HL: Hearing loss; KAP: Knowledge, Attitude and Practice; NHIL: Noise Induced Hearing Loss; ORL: Otorhinolaryngology; OSHA: Occupational Safety and Health Administration; PPE: Personal Protective Equipment’s; PTA: Pure Tone Audiometry; SPSS: Statistical Package for Social Services; SRT: Speech Reception Threshold; WHO: World Health Organization
Noise induced hearing loss is the gradual bilateral sensorineural hearing loss that occurs due to the effect of workplace noise. In all workplaces there is always risk of exposure to occupational noise, but some workers are more susceptible to a higher exposure of workplace noise in comparison to others. Noise-induced hearing loss is one of the most common forms of major health problem, is largely preventable and is probably more widespread than revealed by conventional pure tone threshold testing [2,3]. Noise-induced damage to the cochlea is traditionally considered to be associated with symmetrical mild to moderate hearing loss with associated tinnitus; however, there is a significant number of patients with asymmetrical thresholds and, depending on the exposure, severe to profound hearing loss as well.
A wide variety of NIHLs are work related. Occupational noise is the most common cause of NIHL in adults which is up to now considered incurable and the best approach to it is to utilize maximum protection. An effective noise exposure prevention programme consists of identification of sources of noise and implementation of controlling measures and regulations at working environments as well as performing periodic audiologic evaluation of those who are working at noisy environment . Worldwide, more than one billion people are affected by hearing loss. Noise-induced hearing loss (NIHL) is reported among the most prevalent occupational diseases. However, little is known about the current level of knowledge and attitude towards NIHL among general population .
Hearing impairment is still a major challenge for public health organizations. According to the World Health Organization (WHO), there are approximately 466 million people living with disabling hearing loss, including approximately 34 million children. Furthermore, of these, nearly 90% live in middle and low-income countries. Previous reports have also highlighted the significance of noise-induced hearing loss (NIHL), both work- and recreational activity-related NIHL. In the United States, the estimated percentage of individuals with hearing impairment is around 14.4% of adults aged18 years and above, and approximately 10 million of them suffer from hearing loss due to noise exposure. In the UK, approximately 11 million people have a hearing impairment .
Besides loud noise, there are many other risk factors (modifiable and non-modifiable) which can induce progression of noise-induced hearing loss. Modifiable risk factors include smoking, diabetes and lack of exercise, and non-modifiable risk factors include aging, race and genetics. These factors can overlap with noise and accelerate the occurrence of noise-induced hearing loss. Different genders respond almost equally to noise, but gender influences acoustic risk-taking behaviors, boys engage in significantly more high-risk noise activities than girls. Older people and those who have ever suffered from sensorineural hearing loss are more susceptible to noise. Approximately 23% of those between the ages of 65 and 75 years suffer from mild or severe hearing loss. Over the age of 75 years, about 40% have hearing impairment [7,8].
Noise induced hearing loss as the great burden was reported by ACC that it increases the cost each year in rehabilitation centres in New Zealand. The total cost was almost $43 million in 2004/05, over double those just five years earlier. Across the variety of industry, academic, narrative, and government sanctioned sources on noise-induced hearing loss, one clear thread is evident: that noise-induced hearing loss is a significant and widespread public health issue, it leads to substantial negative impacts upon the lives of those that are afflicted, and while there is no cure for those that are already affected, the condition itself is regarded as essentially preventable .
Noise-induced hearing loss is identified as a significant public health issue worldwide. There is some evidence that the number of new cases is declining in some European countries but increasing in others. Interestingly consistently in the surveys there is apparent increase in the number of people who believe that they are exposed to dangerous noise levels in the workplace . It has been reported that more than one billion people worldwide are affected from noise induced hearing loss [2,3,5]. Also, there is a study conducted in South Africa that showed greater prevalence of NIHL among mine workers . While it is difficult to precisely define and catalogue the disorder, somewhere in the region of 180 million people worldwide may currently be affected with a further 600 million at a high risk of developing it due to excessive noise exposure levels.
Construction, agriculture, manufacturing and metalworking industries show a higher prevalence of noise-induced hearing loss and the greatest losses are consistently among men above the age of 45 years . Occupational Safety and Health Administration (OSHA), has reported that 22 million Americans are exposed to “potentially damaging” noise in the workplace every year. About one-third of Americans in these kinds of workplaces do, in fact, experience noise-induced hearing loss, the CDC has reported . Prevention for NIHL is most used since the problem is still not curable. Action to prevent noise-induced hearing loss is necessary, especially because many causes of permanent hearing loss are preventable.Due to greater development of industries and urbanization in both developed and developing countries NIHL has emerged to be the problem of public health importance [6, 12].
Societal changes are increasing exposure to noise. Although the sensitivity of each individual is different, sound intensity over 85dB can cause noise-induced hearing loss. High levels of noise exposure usually come from occupational noise (such as factories) or recreational noise (such as personal music players). There are also few studies done on prevention on noise induced hearing loss . In Tanzania there was a study conducted that showed many people to have poor knowledge, attitude and practice on prevention of NIHL .
The purpose of this study was to assess the level of knowledge, attitude and practices among factory workers on prevention of NIHL. Determining the predictors of knowledge, attitude and practice of noise induced hearing loss (NIHL) among factory workers was important because it may help prevent a serious irreversible noise induced hearing loss . Also, the results of this study will help health practitioners to emphasize more on the prevention of NIHL among the factory workers and the society at large. The results also provide evidence for forming policies which are more effective and influence better response basing on the ground realities. The study also serves as an opportunity for other colleagues to get knowledge and being aware about noise induced hearing loss on how to prevent it emphazing more to reduce exposure to noise and to use PPE’s . The data obtained from this research serves as a platform of data for further research and for comparison of statistics all over Tanzania.
Descriptive cross-sectional study was used to assess knowledge, attitude and practice on prevention of NIHL among factory workers. This was the study of choice because it was meant to collect information once and there was no follow up of participants, it was also cheap, relatively easy to perform and not time consuming. The study was conducted in April to July 2021. A quantitative method was employed. Such a design was chosen to meet the objectives of the study
Cement Factory and minor publishing industries in Tanzania.
All factory workers with noise exposure.
The inclusion criteria were all factory workers that are on exposure to noise in their working environment and who consented to participate.
Workers in other sections that are not on occupational noise exposure and those who were unable to read Kiswahili.
Data collection methods
Data was collected using Kiswahili questionnaires that were having closed ended questions. This was involving pre-test and actual data collection.
Investigation tools and validity and reliability issues
To test for validity in this study the employed research tool (questionnaires) was pretested and revised to ensure that it gives intended information. The pretest involved a small number of participants that conducted a day before actual data collection day. The essence of pretest study was to ensure that the questionnaire measures and give the required information.
The ethical clearance was obtained from the Institute of reviewer board of Muhimbili University of Health and Allied Science. Informed consent was obtained from the study participants before enrolment.
This study revealed that there were more males 147(79.5%) participants compared to females 38(20.5%). Other studies also found the same results i.e., were more males than females [5,16]. Most of study participants aged between 26-35 years. This was contrary to the study done among Malaysian workers where most participants aged 40-49 years, main reason was due to different settings. However, more than half of participants aged above 50 years . This study found out that most participants were aware of the NIHL and reported that working mates were the main source of information on prevention of NIHL. Majority of the participants had high level of knowledge on prevention of NIHL. However, the study done among iron and steel workers in Tanzania, found that high proportion of participants suffers NIHL because of the low-level knowledge .
It was found that gender and working experience had positive impact on level of knowledge on prevention of NIHL. Zulkefl et al.  found out that gender had no role to the level of knowledge, however they found that working experience and age of workers to have a statistical association with knowledge level . Similar study on level of knowledge done by Jacob et al.  found out that many participants had high level of knowledge . Overall, most participants in this study had good attitude in prevention of NIHL. This was shown to be influenced by level of education of participants. Contrary to these results, it was shown that most workers have poor attitude to NIHL. Factors associated with poor attitude were reported to be perception that noise at work is inevitable and therefore taking precautions for both workers and management is important . Level of education was found to have positive impact on attitude of workers in this study.
Study done by Zulkefl et al.  found out that attitude was influenced by level of education and working experiences, despite that the level of attitude was low . Despite that high proportions of participants reported to have high knowledge and good attitude, few of them practice preventive measures to noise induced hearing loss. Poor practices on prevention of noise induced hearing loss found to be highly influenced by level of education of participants whereby majority of the participants had primary level of education. The same results were found in other studies done in different settings [8,15,19]. Reasons for poor practices reported were poor management , and commitment among workers [21-27].
This study revealed that there is high level of knowledge and good attitude to prevention of noise induced hearing loss to factory workers. Surprisingly, there is poor practice to prevention of NIHL. There is still a problem among workers to practice the measures to prevent noise induced hearing loss despite of knowledge they have. Further studies have to be done on how to bridge the gap between knowledge and practices on prevention of NIHL. Management has to make sure that everyone in working area is abiding to preventive measures as per protocol. Regular health check-up and continuous education to workers for more practice in prevention of NIHL.
Jacob AM, Academy KSHM, Kodyalamoole NK (2016) Knowledge, Attitude and Practice regarding Noise-Induced Hearing Loss among the Bus Personnel in a Coastal City in Karnataka. Internatonal Journal of Preventive, Curative and Community Medicine.