Occupational and Nonoccupational Noise Exposure over 24hr/7day among Underserved Occupations
관리 취약 직업군의 24시간 / 7일간 직업 및 비직업적 소음 노출평가

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보건대학원 환경보건학과
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서울대학교 대학원
noisenoise exposure assessmentnoise induced hearing lossunderserved occupations24 hournonoccupational
학위논문 (박사)-- 서울대학교 보건대학원 : 환경보건학과, 2014. 2. 윤충식.
The World Health Organization (WHO) has stated that hearing loss is one of the top ten health problems worldwide, and that noise induced hearing loss (NIHL) is the leading occupational disease. The true prevalence of NIHL may be higher than expected because of the small proportion of occupations assessed and under-reporting. Coverage of risk assessment should increase to determine the true prevalence of NIHL. In the same context, the new Noise Directive 2003/10/EC went into effect in 2006. The EU emphasized that noise exposure assessments should cover all sectors and lowered the noise exposure limit. Occupational health research and services in Korea are still concentrated in the manufacturing sector.
The purposes of this study were to assess the occupational noise exposure of underserved occupations, as well as their nonoccupational activities, which have been excluded from previous studies. Construction workers, firefighters, musicians, service workers, office workers, housewives, and students were selected as underserved occupations. Although construction workers, musicians, firefighters, and service workers are exposed to occupational noise, an assessment of noise exposure among them has rarely been conducted. Office workers, housewives, and students are not thought to be adversely affected by noise. However, an occupational noise exposure limit was established on the assumption that nonoccupational noise exposure could be ignored
however, that needs verification because environmental noise continues to grow in extent, frequency, and severity as a result of population growth, urbanization, and technological developments.

∙ Assessment of apartment construction worker noise exposure
A noise exposure assessment was performed for 139 construction workers from 10 construction trades working at 53 apartment construction sites located in the northern part of Gyeonggi-do. The mean LMOEL for 139 dosimeter samples was 87.8 ± 4.3 dBA. The mean noise exposure level of each construction trade (trade mean) was calculated. Significant differences were observed between construction trades. The highest LMOEL values were measured for concrete chippers (93.2 ± 2.6 dBA), followed by ironworkers (88.4 ± 0.7 dBA), concrete finishers (88.3 ± 2.7 dBA), masonry workers (87.7 ± 1.9 dBA), pile driver operators (85.6 ± 1.7 dBA), concrete carpenters (84.9 ± 2.4 dBA), interior carpenters (83.5 ± 2.1 dBA), and other groups (81.4 ± 2.2 dBA). These results indicate that almost all construction workers in this study are at risk of NIHL, and that construction trades are a useful exposure metric at apartment construction sites.

∙ Assessment of noise measurements made with continuous monitoring over time (24 hours/7 days) among underserved occupations
The average Leq 24hr,w among 47 individuals in the underserved occupations was 74 dBA (range, 64-96 dBA). The average Leq 24hr,w was highest for Korean traditional music apprentices, followed by heavy equipment operators, firefighters, service workers, office workers, industrial hygienists, graduate and undergraduate students, and housewives (89, 77, 76, 76, 75, 71, 71, and 71 dBA, respectively, p < 0.001). A total of 38 (80.9%) were exposed to noise levels > 70 dBA, which corresponds to the WHO exposure limit. Additionally, 60% (15 of 24) of the participants with occupations thought to have low noise exposure (office workers, housewives, and students) were over the recommended limit.
Furthermore, the mean nonoccupational noise exposure level of all participants (72 ± 6 dBA) that normalized to a nominal 24h was over the recommended limit
thus, nonoccupational noise exposure may not be negligible.

∙ Task-specific noise exposure assessment of firefighters
The firefighter noise-sample datasets revealed that most firefighters are exposed to higher than recommended exposures at a low-action value of Lep,d (shift-adjusted daily personal noise exposure level) = 80 dBA. The highest mean level of noise exposure was for rescuers (84.6 ± 6.2 dBA), followed by drivers (83.3 ± 2.7 dBA) and suppressors (79.5 ± 3.5 dBA). Noise measurements were combined with time-at-task information to concentrate on noise exposure, which showed that 82.3% of sound exposure occurred while checking equipment and responding to fire or emergency calls. This information can be obtained only through a task-specific noise exposure assessment, which is useful for controlling noise.

∙ Hearing among male firefighters: A comparison with hearing data from
screened and unscreened male population
A comparison of firefighter hearing threshold levels (HTLs) with those of an otologically normal male Korean population (KONP) and non-industrial noise-exposed male Korean population (KNINEP) by age and frequency showed that the firefighter HTLs were significantly increased (poorer hearing) across most age groups and frequencies compared with those of the KONP. The firefighter HTLs were worse in the younger age groups (< 45 years) but not different in the older age groups (> 45 years) compared with those of the KNINEP. The firefighter age-adjusted HTLs were significantly worse than those of the KONP (prevalence ratio [PR] = 5.29, p < 0.001), but not different from those of the KNINEP (PR = 0.99, p = 0.550). Rescuers (PR = 1.006, p < 0.001) had worse hearing than the unscreened general population after adjusting for age. The noise exposure assessments showed that some firefighters were at risk for NIHL, consistent with the results of the HTL comparisons.
In brief, the underserved occupations assessed in this study, including construction workers, Korean traditional music apprentices, and firefighters, are almost at risk of NIHL. The hearing levels of younger firefighters and rescuers were worse than expected by normal age alone. These data indicate the need for a comprehensive assessment and noise reduction efforts in these occupational groups. The general assumption that housewives, students, and office workers are exposed to negligible noise may be incorrect. Nonoccupational noise exposure should be considered when assessing noise health hazards.
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Graduate School of Public Health (보건대학원)Dept. of Environmental Health (환경보건학과)Theses (Ph.D. / Sc.D._환경보건학과)
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