Risk Ratio of Noise-Induced Hearing Loss in Mineral Ore Processing Industry Workers

The mining industry employs machines and equipment that generate noise. Noise is an unwanted sound that can cause discomfort to listeners, leading to health issues. One of the health problems caused by noise is Noise-Induced Hearing Loss (NIHL), a hearing impairment resulting from continuous exposure to hazardous noise levels. The Permissible Noise Exposure (PNE) value in the mining industry is set at 85 dB(A). This study aims to assess the risk of noise exposure in relation to the occurrence of NIHL among mineral ore processing workers in the mining industry in Indonesia. The study employs the epidemiological frequency measurement method Relative Risk Ratio (RR). The study categorizes workers into two groups: native mining industry workers and contractor workers in the mining industry. The RR results for each group are 2.68 and 2.76 (RR>1), respectively. These results indicate that the noise-exposed group is at a 2.68-2.76 times higher risk of experiencing NIHL compared to the non-exposed group. Noise exposure in the mining industry poses a high risk of NIHL to workers, necessitating control measures. Control measures involve reducing noise exposure using Personal Protective Equipment (PPE) such as earplugs for workers in noisy areas. The use of earplugs can reduce noise by around 24-32 dB(A). Additionally, some industrial companies conduct awareness programs to encourage workers to use earplugs or other PPE, known as the hearing conservation program.


The first section in your paper
The mineral ore processing industry has seen significant technological advancements.This technology includes various machines and production equipment [1].Examples of production machines include grinding machines, which have a positive impact by accelerating production to several tons per day [2].However, behind all of this, grinding machines also have negative aspects, including generating noise [3].Noise is an unwanted sound resulting from certain activities or operations at specific levels and times, and it can lead to human health issues and environmental discomfort [4].
According to the Regulation of the Minister of Manpower and Transmigration of the Republic of Indonesia No. PER.13/MEN/X/2011, the permissible noise exposure level (NAB) is set at 85 dB(A), with exposure not exceeding 8 hours per day or 40 hours per week.Such noise can significantly disrupt the comfort and health of workers in the area [5].Approximately 12% or around 600 million people, more than the global population, are at risk of experiencing hearing impairment due to noise, making it a global public health issue.The World Health Organization (WHO) estimates that one-third of all cases of hearing impairment can be attributed to noise exposure [6,7].In one case, noise levels at CV Kencana Indah in West Kalimantan ranged from 76.2 to 100.41 dB(A), exceeding the established NAB [8].
In February 2023, noise sampling or measurement was conducted on a grinding machine, which reached 95.5 dB(A).This result exceeded the 85 dB(A) limit [9].A report from the Hearing Impairment Commission in the UK in 2013 estimated that 18,000 people suffered from Noise-Induced Hearing Loss (NIHL) caused by workplace noise [10].Noise originating from production machines is influenced by several factors, including sound pressure, absorption capacity, sound intensity, and sound frequency.These noise factors have a significant impact on the noise generated by the sources.If noise is not well controlled, it can lead to discomfort in the production area, affecting workers in the mineral ore industry.
One of the mineral ore processing industries in Indonesia employs advanced technology, including production machines that generate significant noise.The industry also conducts medical health assessments of its workers to assess the risks associated with noise exposure.The process of assessing the health risks to workers exposed to noise is done by calculating the epidemiological association measure, Risk Ratio/Relative Ratio (RR) [12].This measure is used to evaluate the risk of NIHL among workers exposed or not exposed to noise.The exposed area referred to is the one close to the noise source.).

Methods
This research was conducted in one of the mineral ore processing industries in Indonesia and utilized secondary data.The data were obtained from the summary of health examination results, specifically audiometry results, for both permanent and contractor workers from various companies working in the mineral ore processing industry.The research design employed in this study is a retrospective cohort study.It looks at the present effects and then examines the causative factors retrospectively.
The research methodology employed in this study utilizes the epidemiological association measure, Risk Ratio/Relative Ratio (RR).This association measure is well-suited for research with a retrospective cohort design.RR involves comparing the health risks between the exposed group and the non-exposed group.The calculation of RR in this research is based on a 2x2 table, as described in Table 1.In addition to the table, there is also a formula for calculating RR.The risk is the same between the exposed group and the non-exposed group RR > 1: There is an increased risk in the exposed group compared to the non-exposed group RR < 1: There is a decreased risk in the exposed group compared to the non-exposed group

Methods
In this study, the results of RR are divided into two categories.The first category calculates RR for the staff workers from the industry, and the second category calculates RR for the contractor workers.

Result
This research involved 1,723 workers in one of the divisions of the mineral ore processing industry in Indonesia.These 1,723 individuals were divided into two groups: permanent workers and contractors.The first group consisted of permanent workers who were directly employed by the company operating in the mineral ore processing industry.The second group comprised contractor workers who were under the supervision of partner companies.Among the original staff workers totalling 506 individuals, 93 of them were exposed to noise and experienced Noise-Induced Hearing Loss (NIHL), while 222 of them were exposed but did not experience this condition.There were 21 individuals who were not exposed but experienced hearing impairment, and 170 individuals who were neither exposed nor experiencing hearing impairment.
The second group consisted of 1,217 contractor workers.This group included 889 individuals exposed to noise, out of which 150 were exposed to noise and experienced NIHL, while 739 were exposed but did not experience any health issues.Additionally, 328 workers were not exposed, with 20 of them experiencing health problems and 308 remaining both unexposed and unaffected.The obtained RR values for both permanent and contractor workers were 2.68 and 2.76, respectively.These RR values are greater than 1, indicating an increased risk in the exposed group compared to the non-exposed group.In the case of permanent workers, this means that those working in the field (near noisy machinery) are 2.68 times more likely to develop NIHL than permanent workers who do not work in the field or in office areas that are not directly within the production process.Similarly, for contractor workers, the calculated RR was 2.76.
Contractor workers in the mineral ore processing industry who work in the field (near noisy machinery) are 2.76 times more likely to develop NIHL compared to contractor workers who do not work in the field or in office areas that are not directly within the production process.Workers who work in the field or in close proximity to noisy sources are at a higher risk of developing NIHL.This is because they are exposed to noise near-continuously, approximately 8 hours a day, compared to office workers whose work areas are far from production activities.Office workers typically perform administrative tasks and other duties that do not require them to be in the vicinity of production areas [13].Office workers have a lower risk compared to industrial workers, as industrial workers are directly exposed to the noise emitted by machinery.High noise levels ranging from 88 to 97 dBA can be found near operating machinery, and each operational machine contributes to the overall sound pressure level at specific positions [12].The sound pressure received by industrial workers is naturally higher than that received by office workers, influenced by the attenuation of sound energy.Attenuation depends on various factors, including the distance between the noise source and the receiver [14].Additionally, it is affected by factors such as the presence of hard surfaces around the sound source, which act as barriers to the propagation of noise to further areas [15].
The distance between the noise source and the receiver also affects the level of noise received by workers [16].Noise barriers such as walls, columns, and structures in the mineral ore processing industry play a role in why the sound pressure received by office workers is lower than that received by industrial workers [17].Other factors affecting differences in sound pressure reception include the design of the roof structure in ore processing factories.Roofs made of zinc-aluminum are believed to contribute to increased noise levels during heavy rainfall [18].Additionally, there is a slowing down of noise propagation in the atmosphere, influenced by humidity and air temperature [19].These factors explain the differences in noise levels received by industrial workers and office workers.

Conclusion
The obtained RR > 1, which means an increased health risk in the exposed groups.To mitigate this risk, control measures should be implemented to minimize the exposure of workers.These control measures can include the use of earplugs, earmuffs, and other protective devices.There are advantages and disadvantages associated with both earplugs and earmuffs.Earplugs have the advantage of being small in size, easy to use, and compatible with wearing glasses.They are also comfortable to wear in hot and humid conditions.
However, earplugs may require some time to adjust to, need to be used with care, and can be easily lost.On the other hand, earmuffs are easy to use, provide maximum noise reduction, and can be used with minor ear infections.However, they have the disadvantage of being larger and heavier, making them less compatible with glasses and other safety equipment such as helmets.Despite these drawbacks, both earplugs and earmuffs are highly effective in reducing noise exposure.

Table 2
explains that the calculation of RR yields a value of 2.68.Table3explains that the calculation of RR yields a value of 2.76.Based on the calculations for both types of workers, there is a difference, with the contractor workers having a higher value by 0.08.Table2x2Toward Contractor Employees at Ore Mineral Processing Industry