Occupational noise exposure and hearing protector use in Canadian lumber mills

Noise exposure is probably the most ubiquitous of all occupational hazards, and there is evidence for causal links between noise and both auditory and nonauditory health effects. Noise control at source is rarely considered, resulting in reliance on hearing protection devices to reduce exposure. A comprehensive noise survey of four lumber mills using a randomized sampling strategy was undertaken, resulting in 350 full-shift personal dosimetry measurements. Sound frequency spectrum data and information on hearing protector usage was collected. A determinants-of-exposure regression model for noise was developed. Mean (L(eq,8hr)) exposure level was 91.7 dBA, well above the exposure British Columbia (BC) limit of 85 dBA. Of 52 jobs for which more than a single observation was made, only 4 were below the exposure limit. Twenty-eight jobs had means over 90 dBA, and four jobs had means over 100 dBA. The sawmill and by-products departments of the lumber mills had the highest exposure to low frequency noise, while the planing and saw filing areas had the highest exposure to high frequency noise. Hearing protector use was greatest among those exposed above 95 dBA, and among those exposed between 85 and 95 dBA, self-reported use was 84% for 73% of the time. The determinants of exposure model had an R(2) of 0.52, and the within-participant correlation was 0.07. Key predictors in the final model were mill; enclosure and enclosure construction material; and certain departments, jobs, and noise sources. The study showed that workers in lumber mills are highly exposed to noise, and although the prevalence of the use of hearing protection is high, their use is unlikely to provide complete protection again noise-induced hearing loss at the observed exposures. Determinants of noise exposure modeling offers a good method for the quantitative estimation of noise exposure.     

The effectiveness of hearing protection among construction workers

Effective hearing conservation programs in the construction industry are rare. Where programs are present, they often rely on workers' use of hearing protection devices (HPDs) rather than on exposure controls to reduce noise exposure levels. Dependence on HPDs for protection from high noise is problematic, as the protection provided by the HPD depends on both the HPD's attenuation level and the time the HPD is used. This article presents an analysis of data on noise exposure and hearing protection among construction workers drawn from several large datasets covering nine construction trades. A unique combination of 1-min dosimetry noise exposure levels and simultaneous self-reported use of HPDs was evaluated, as were occupational and nonoccupational HPD use data collected by questionnaire as part of a longitudinal study of noise exposure and hearing loss among apprentices. Direct measurements of HPD attenuation were also made on workers at their work site. The workers assessed in this study were found to use hearing protection less than one-quarter of the time that they were exposed above 85 dBA. Workers who reported always using HPDs in high noise on questionnaires were found to wear them only one-third of the time their exposures exceeded 85 dBA. Workers' self-reported use of HPDs during most noisy nonoccupational activities was also found to be low. Direct attenuation measurements found that workers were able to achieve more than 50% of the rated attenuation of their HPD on average, but that the variability in achieved attenuation was large. When the measured HPD attenuation levels and use time data were combined, the effective protection afforded by HPDs was less than 3 dB, a negligible amount given the high exposure levels associated with construction work. However, there was substantial variation in effective protection among the different trades assessed. These results demonstrate the need for better hearing conservation programs and expanded noise control efforts in the construction industry.     

Assessing noise exposures in farm youths

OBJECTIVE: This exploratory study evaluated the feasibility of field exposure assessment methods to characterize the noise sources and levels that farm youths experience during a typical workday. METHODS: Detailed exposure assessments were performed with a sample of 10 farm youths working on Vermont dairy farms to characterize potential noise hazards typical in the farm setting. Personal and area noise measurements were taken using noise dosimeters. Information concerning work- and non-work-related noise exposure histories was collected via questionnaire. RESULTS: The average age was 15.5 years (SD 2.5, range 10-18). Youths started working at an average age of 8.4 years (SD 2.3, range 6-12) and during the summer months worked an average of 41.3 hours per week (SD 32.3, range 2-68). Two youths exceeded the OSHA action level, having eight-hour time-weighted averages of 95 dBA and 92 dBA, or alternatively, doses of 206% and 127%. (The OSHA action level for the hearing conservation amendment is an eight-hour time-weighted average of 85 dBA or a dose of 50%.) Participants exceeding the action level reported working with tractors, skid steers (Bobcats), and all-terrain vehicles and doing general barn work. Additional sources of noise exposure included a mechanical silo elevator, chain saw, and wood splitter. CONCLUSION: Two of the monitored subjects were overexposed to noise in their farm work. Youths may be exposed to noise levels that exceed adult OSHA hearing conservation amendment action level as part of their daily farm activities.     

Alternative metrics for noise exposure among construction workers

Although the exposure-response relationships for noise-induced hearing loss are relatively well established, there is not complete agreement on which metrics of noise exposure best represent risk of hearing damage. In particular, while L(eq), based on a 3 dB exchange rate (ER) is used by most agencies, US OSHA's standard is based on the L(avg), which uses a 5 dB ER. In addition, peak levels of exposure, which are commonly found in some industries, including construction, are believed to increase risk above that predicted by the L(eq). This paper presents an analysis of a large database of noise exposures among construction workers, comparing several noise metrics, and their application to a cohort of construction workers. Metrics examined were the L(avg), L(eq) and L(max), expressing average levels of exposure across an exposure interval. Two novel metrics were derived from these monitored metrics, L(eq)/L(avg) and L(max)/L(eq), as measures of exposure variability and 'peakiness', respectively. A total of 730 workshifts, including data on 361 492 min of exposure to workers in nine trades were examined. Correlations between average metrics (L(eq), L(avg) and L(max)) are generally very high, while the variability metrics are poorly correlated with either average levels, or with each other, indicating that they characterize different aspects of exposure. Alternative models for estimating exposure for the cohort were considered and the use of a task-within-trade specific mean level was adopted. The task-specific estimates of exposure using the various metrics will be applied to the cohort's work history to explore the importance of these alternative metrics in estimating risk of noise-induced damage.     

Noise exposure assessment among groundskeepers in a university setting: A pilot study

Approximately 870,000 U.S. workers are employed as landscaping and groundskeeping workers who perform various tasks and use a variety of tools that expose them to high noise levels, increasing their risk to noise-induced hearing loss (NIHL). Several studies on noise exposure and NIHL in other job sectors have been published, but those on groundskeepers are very limited. This study aims to characterize the noise exposure of groundskeepers. Participants were monitored over their entire work shift for personal noise exposure by wearing noise dosimeters at shoulder level, 4 in from the ear. Using two different dosimeter settings (OSHA and NIOSH), the time-weighted averages (TWAs) and 1-min averages of noise exposure levels in decibels (dBA) were obtained. The participants were also asked to fill out an activity card daily to document their tasks, tools used, location and noise perception. Sound pressure levels (SPLs) produced by various groundskeeping equipment and tools were measured at full throttle near the ear of the operator using a sound level meter. These measurements were used to assess worker noise exposure profiles, particularly the contributing source of noise. The overall mean OSHA and NIOSH TWA noise exposures were 82.2±9.2 (range of 50.9–100 dBA) and 87.8±6.6 dBA (range of 67.2–102.9 dBA), respectively. Approximately 46% of the OSHA TWAs exceeded the OSHA action limit of 85 dBA. About 76% of the NIOSH TWAs exceeded 85 dBA, and 42% exceeded 90 dBA. The SPLs of equipment and tools measured ranged from 75– 106 dBA, most of which were at above 85 dBA and within the 90–100 dBA range. Hand-held power tools and ride-on equipment without enclosed cab may have contributed significantly to worker noise exposure. This study demonstrates that groundskeepers may be routinely exposed to noise levels above the OSHA and NIOSH exposure limits, and that the implementation of effective hearing conservation programs is necessary to reduce their risk to NIHL.     

A study of classroom acoustics and school teachers’ noise exposure,voice load and speaking time during teaching,and the effects on vocal and mental fatigue development

Objectives

The study investigated the noise exposure in a group of Danish school teachers. The aims were to investigate if noise posed a risk of impairment of hearing and to study the association between classroom acoustical conditions, noise exposure, vocal symptoms, and cognitive fatigue.

Methods

Background noise levels, vocal load and speaking time were measured on 35 teachers during actual classroom teaching. The classrooms were characterized acoustically by measurements of reverberation time. Before and after the workday, the teachers answered a questionnaire on fatigue symptoms and carried out two cognitive test tasks sensitive to mental fatigue.

Results

The average noise level during the lessons was 72 dB(A), but during indoor sports activities the average noise level increased 6.6 dB(A). Room reverberation time (range 0.39–0.83 s) had no significant effect on the noise level. The teachers were talking with a raised voice in 61 % of the time, and the vocal load increased 0.65 dB(A) per dB(A) increase in the average lesson noise level. An increase in voice symptoms during the workday correlated significantly with individual average noise exposure, and a decrease in performance in the two-back test correlated significantly with individual average vocal load.

Conclusions

Noise exposure in general classrooms posed no risk of noise-induced hearing impairment in school teachers. However, the results provide evidence for an association between noise exposure and vocal load and development of vocal symptoms and cognitive fatigue after work.     

职业性噪声对暴露人群健康效应初步分析

目的分析工业作业场所职业性噪声对暴露人群的健康效应。方法于2005年随机抽取南方某市部分噪声暴露工厂,按《作业场所噪声测量规范》(WS/T69-1996)进行测点选择和测量噪声强度[dB(A)],按照《职业健康监护管理办法》对其职业性噪声暴露人群进行健康检查,并对4家产生稳态噪声、4家产生脉冲噪声的工厂的暴露人群的健康效应进行比较分析。结果共对84家工厂的1374个噪声作业点进行噪声强度测定,噪声平均强度83.40[dB(A)],作业点噪声强度90[dB(A)]以上占23.22%(319/1374),85~89[dB(A)]占25.47%(350/1374),85[dB(A)]以下占51.31%(705/1374),超标率为48.69%(699/1374);7464例噪声暴露工人的健康检查结果显示,听力损伤检出率为20.47%(1528/7464),心电图异常检出率7.32%(546/7464),心率异常检出率为3.93%(293/7464),血压偏高检出率为3.71%(277/7464);稳态噪声和脉冲噪声的平均强度分别为84.96、88.49[dB(A)],两者的等效噪音强度差异无统计学意义(P>0.05);脉冲噪声暴露人群的听力损伤、血压偏高检出率均高于稳态噪声的(P>0.01)。暴露人群的听力损伤检出率与暴露水平存在正相关关系(rs=0.952 4,P<0.01)。结论职业性噪声暴露对人群健康效应的影响表现为脉冲噪声对噪声暴露者的危害比稳态噪声大;噪声强度和噪声暴露者的听力损伤检出率存在剂量反应关系。     

Occupational exposures during routine activities in coal-fueled power plants

Limited information is available on occupational exposures during routine, nonoutage work activities in coal-fueled power plants. This study evaluated occupational exposures to the principal contaminants in the facilities, including respirable dust (coal dust), arsenic, noise, asbestos, and heat stress. The data were collected over a 3-month period, during the summer of 2001, in 5 facilities that were chosen to be representative of the coal-fueled power plants of a large southeastern power-generating company. Each of the facilities was divided into 5 similar exposure groups based on previous exposure assessments and job tasks performed. From 4 of the 5 facilities, 392 air samples and 302 noise samples were collected with approximately 50 respirable coal dust, 32 arsenic, 15 asbestos, and 70 noise samples from each of the 4 plants. One of the previously surveyed facilities was also evaluated for heat stress, and 1 additional coal-fueled power plant was surveyed for a total of 20 personal heat stress samples. Personal monitors and area WBGT monitors were used. Of the nearly 400 air samples collected, only 1 exceeded the allowable occupational exposure value. For the noise samples, 55 (approximately 18%) were equal to or greater than the Occupational Safety and Health Administration (OSHA) 8-hour hearing conservation program level of 85 dBA, and 12 (approximately 4%) were equal to or greater than the OSHA 8-hour permissible exposure level of 90 dBA. Heat stress monitoring at the facilities indicates that 26% of the 1-hour TWAs were exceeded for one or all of the recommended heat stress limits. The data also concluded that some work sites were above the heat stress ceiling values recommended by the National Institute for Occupational Safety and Health (NIOSH). Four of the 20 employees personally monitored exceeded the recommended limits for heart rate or body core temperature. This suggests there is a potential for heat strain if signs and symptoms are ignored. Recommendations are made to better control the heat stress exposure.     

Occupational exposures to noise resulting from the workplace use of personal media players at a manufacturing facility

This study examined the contribution of noise exposures from personal media player (PMP) use in the workplace to overall employee noise exposures at a Colorado manufacturing facility. A total of 24 workers' PMP and background noise exposures were measured. Twelve PMP users worked in high-background-noise exposure (HBNE) areas, and 12 worked in low-background-noise exposure (LBNE) areas. The self-selected PMP listening level of each worker was measured using an ear simulator, and the background noise of each employee workstation was measured using a sound level meter. Workers' self-reported PMP duration of use, PMP listening exposure levels, and background noise levels were used to estimate the daily occupational noise exposures. Measured background noise levels averaged 81 dBA for HBNE workers and 59 dBA for LBNE workers. Measured, free-field equivalent listening exposure levels were significantly greater for HBNE workers (85 dBA) compared with LBNE workers (75 dBA) (p = 0.0006). Estimated mean daily noise exposures for both groups were below the ACGIH threshold limit value for noise of 85 dBA8-hr time weighted average (TWA), specifically 84 dBA TWA for HBNE workers and 72 dBA TWA for LBNE workers. Three of 12 (25%) HBNE workers had estimated exposures greater than 85 dBA TWA when only background noise was considered, yet when PMP use was also considered, 6 of 12 (50%) had estimated exposures greater than 85 dBA TWA, suggesting that PMP use doubled the number of overexposed workers. None of the LBNE workers had estimated exposures greater than 85 dBA TWA. The contribution of PMP use to overall noise exposures was substantially less among HBNE workers than LBNE workers due to the disproportionate selection of noise-attenuating headsets among HBNE workers compared with LBNE workers. It is recommended that the facility management either restrict workplace PMP use among HBNE workers or require output-limiting technology to prevent occupational noise-induced hearing loss.     

High-frequency audiometry for the early diagnosis of occupational acoustic trauma

We investigated a total of 537 patients (68 men, 469 women) working in the textile industry to ascertain their hearing level in the conventional hearing range as well as in the HF range. The persons tested work at 3 different noise levels (80-84, 85-89 and 90-94 dB [A] Leq). The differences in the hearing thresholds of the three sound level groups mentioned above were checked by means of discrimination analysis. The first hearing level changes noise levels below 90 dB develop mainly in the HF range; in the conventional hearing range, however, the hearing levels remain unchanged even during long exposure times. Hearing level impairment in the conventional range occurs only in the sound level group of 90-94 dB (A) Leq without attaining any social importance. The tests clearly show that if the noise level damage risk criterion of 85 dB (A) Leq at which hearing is impaired, is not exceeded any hearing lesions involving social hearing loss are definitely avoided.     

用个体暴露评价脉冲噪声与稳态噪声所致高频听力损失的关系

目的用个体噪声暴露测量数据比较工业脉冲噪声与稳态噪声所致高频听力损失剂量反应关系的异同。方法1998至1999年,以32名接触脉冲噪声的机械制造工人和163名接触稳态噪声的纺织工人为观察对象,用噪声剂量计采集8h工作期间的噪声暴露数据,计算8h等效声级(LAeq.8h),并按等能量原理将LAeq.8h和噪声作业工龄合并为累积噪声暴露量(CNE)。用常规方法测量工人左右耳气导听阈,按GBZ492002对听阈做年龄性别校正,并诊断是否为高频听力损失。结果脉冲噪声组的CNE[(103.2±4.2)dB(A)·年]明显低于稳态噪声组[(110.6±6.0)dB(A)·年],脉冲噪声组高频听力损失患病率(68.8%)与稳态噪声组(65.0%)相似,分层分析和趋势卡方检验证实,两组CNE与高频听力损失患病率间均存在典型的剂量反应关系,差异有统计学意义;脉冲噪声100～104和105～109dB(A)·年两组的高频听力损失患病率(76.9%和90.9%)高出稳态噪声组(30.4%和50.0%)约1倍。logistic回归模型显示,脉冲噪声组CNE与高频听力损失患病率的剂量反应关系曲线与稳态噪声组相比出现曲线左移,斜率增大。结论采用个体噪声暴露数据计算时,在能量相同的情况下,脉冲噪声所致高频听力损失的危害大于稳态噪声。     

两种测量方法评价稳态噪声暴露与高频听力损伤的剂量-反应关系

目的 比较环境噪声水平、个体噪声暴露和累积噪声暴露量评价稳 态噪声所致听力损伤剂量－反应关系的优劣。方法 用个体计量仪采集8小时工作期间挡车工的噪声暴露数据,并将数据传输至微机存储和分析。选择细砂、布机车间使用不同类型机器的4组工人作为观察对象,每组选择3－5人,分别在早、中、晚班各测量1个班次的个体噪声暴露数据;用网格法和普通声级计测量每组工人工作环境的噪声水平,同时对该纺织厂接触稳态噪声的163名工人进行了问卷和听力检查。结果 经年龄、性别校正后的高频听力损伤患病率为64．4％;语频听力损伤患病率为2．5％,其中高频听力损伤患病率随噪声暴露的剂量增大而升高,呈现典型的剂量－反应关系。经趋势卡方检验和和Logistic回归模型拟合,累积噪声暴露量评价剂量－反应关系的效果优于噪声级,个体噪声暴露的效果优于环境噪声水平。结论 个体噪声暴露和累积噪声暴露量是评价稳态噪声暴露与高频听力损伤剂量－反应关系最好的暴露评价指标。     

Evaluation of occupational environment in two textile plants in Northern India with specific reference to noise

Occupational Noise exposure has been linked with a range of negative health effects by various researchers. The resulting injury of occupational hearing loss is also a well recognized and global problem. To protect workers from hearing damage due to noise exposure and other related health effects, a vast store of knowledge has been accumulated till date about its nature, etiology and time course. There is still ignorance, amongst majority of people working in industries in developing and third world countries including India about ill effects of exposure to high values of noise. The study being reported here has been carried out in two textile plants located in Northern Indian state of Punjab. Equivalent sound pressure level L(eq) has been measured in various sections of these plants with the help of a Class-I type digital sound level meter. The noise spectrum has been evaluated with the help of 1/3 octave filter set. A cross sectional study involving 112 workers exposed to different levels of occupational noise has been conducted. The results of the study establish the fact that noise level in certain sections of the plants i.e Loom Shed, Spinning, Ring Frame, TFO Area is more than the acceptable limit of 90 dBA for 8 h exposure stipulated by OSHA. The noise level in other sections like carding, blow room, combing etc., although is less than 90 dB(A), but is quite higher than limits used for assessment of noise for community response. Octave band analysis of the noise shows the presence of high sound level in 4,000 Hz frequency range, which can be a major reason for causing occupational hearing loss. The results of the interview questionnaire which included a number of parameters reveal the following; (i) only 29% workers are aware about the effects of noise on health (ii) 28% workers are using ear protectors (iii) the satisfaction with the working environment is related to noise level, as workers exposed to comparatively less noise level report better satisfaction (iv) 70% of the workers reported that high noise level causes speech interference (v) 42% workers report the noise to be annoying. The study thus demonstrates the presence of gross occupational noise exposure in both the plants and the author believes that occupational noise exposure and the related effects in India is a widespread problem.     

Noise exposures of rail workers at a North American chemical facility

BACKGROUND: Both continuous and impact noise exposures of rail yards and railways have been historically understudied. We summarize noise exposures to rail workers at a large chemical facility in North America. METHODS: Rail workers were surveyed over the course of three 12-hr shifts. Personal noise dosimeters were used to derive a 12-hr time-weighted average (L(AVG)), an 8-hr time-weighted average (L(TWA)), and a percent dose. Peak and maximum sound levels were also recorded during each sampling period. Six workers were sampled on three separate days for a total of 18 full-shift noise samples. RESULTS: Full-shift noise exposures were all below the Occupational Safety and Health Administration's (OSHA) permissible exposure limit (PEL) and action level for a 12-hr workday. Peak impact sound levels exceeded 140 dB in 17 of 18 samples (94%) with a mean peak sound level of 143.9 dB. Maximum continuous sound levels were greater than 115 dBA in 4 of 18 samples (22%) with a mean maximum sound level of 113.1 dBA. The source of peak impact sound levels was a daily exposure to a concussion caused by a sudden break in a freight airline. CONCLUSIONS: Rail workers at this facility are at risk of noise induced hearing loss from high impact noise exposures. Peak impact and maximum continuous sound levels can be attenuated through the use of hearing protection or by increasing distances from railroad noise sources.     

噪声对职业接触人群血清SOD、T-AOC及MDA水平的影响

目的探讨噪声对职业接触人群血清中超氧化物歧化酶(SOD)、总抗氧化能力(T-AOC)、丙二醛(MDA)的影响。方法选择某五金制造厂打磨岗位97人为实验组[平均接噪强度为87.4±1.9 dB(A)],某电子厂装配流水线接触噪声强度低于噪声职业接触限值112人[平均接噪强度为82.5±2.0 dB(A)]为对照组,测定不同噪声接触强度作业人员血清中总SOD活力、T-AOC、MDA水平。同时对两组接触工人进行纯音听阈测试。结果接触噪声强度高的实验组总SOD活力比接触噪声强度较低的对照组有所下降(P0.05),T-AOC水平两组相比,差异无统计学意义,接触噪声强度高组比对照组MDA水平升高,差异有统计学意义(P0.05);两组语频听力与高频听力损失比较,差异有统计学意义(P0.01);血清中MDA与总SOD活力水平呈负相关,与双耳高频听力损失呈正相关(P0.05)。结论长期接触噪声对劳动者的抗氧化系统存在影响。     

The accuracy of self-reported high noise exposure level and hearing loss in a working population in Eastern Saudi Arabia

Objective: To determine the accuracy of questions in identifying subjects occupationally exposed to high noise level and those with hearing loss using noise dosimeter and pure-tone air conduction audiometry as the gold standards.Design: A cross-sectional study involving 259 noise-exposed workers selected randomly from two factories in Eastern Saudi Arabia. Personal noise exposure was determined using a noise dosimeter. The hearing impairment for each subject was assessed using otoscopic examination and audiometry. Each subject completed a comprehensive questionnaire including questions about noise exposure and hearing loss.Results: Eighty five percent of the total workers reported exposure to high noise level, compared to 76% found to be exposed to a high noise level defined as more than 85dB (A) as determined by noise dosimeter. The prevalence of audiometric hearing loss (threshold average of 25dB HL or more in any ear) was 32.4% for the low frequency average (0.5, 1 and 2kHz), 47.9% for the all frequency average (0.5, 1, 2. 4 and 8kHz) and 65.6% for the high frequency average (4 and 8kHz). However, the percentage of the subjects who reported hearing loss ranged between 3.9% and 85.3% depending on the question used as indicator of hearing loss.The question “Do you consider the noise level where you are working now high?” was the most sensitive in correctly identifying subjects exposed to a noise level of more than 85dB (A) (sensitivity=93.4%) and subjects with hearing loss (sensitivity>86%) compared with other questions evaluated. However, it overestimated the prevalence rate determined by audiometryConclusion: We conclude that in industries where facilities for an objective assessment of noise exposure and hearing loss are not available, questions addressing noise exposure and hearing loss might be a useful alternative means for screening subjects exposed to high noise level and those with hearing loss for the purpose of designing and implementing hearing conservation program.     

广州市部分企业噪声作业工人听力损失现况分析

目的对广州市部分企业噪声作业工人听力损失现况进行分析,以达到保护工人听力的目的。方法以部分企业长期接触噪声的440名工人为研究对象,测量等效A声级(LAeq)。按等能量原则将LAeq和噪声作业工龄合并计算累积噪声暴露量(CNE);用logistic回归模型分析听力损失的相关因素。结果作业环境噪声强度超标率为41.20%,噪声强度均值为(89.30±4.57)dB(A)。440例噪声作业工人听力损失检出率为23.86%,听力损失与耳塞防护、工龄、年龄和CNE存在正相关关系(P0.05)。非条件logistic回归分析结果显示,年龄、工龄可能是听力损失的危险因素(偏回归系数为正值,OR值1)。结论在有佩戴耳塞防护的情况下,CNE作为听力损失的评价指标不敏感,佩戴耳塞仍是目前最好的防护措施。     

Assessment of noise exposure during commuting in the Madrid subway

Because noise-induced hearing impairment is the result not only of occupational noise exposure but also of total daily noise exposure, it is important to take the non-occupational exposure of individuals (during commuting to and from their jobs, at home, and during recreational activities) into account. Mass transit is one of the main contributors to non-occupational noise exposure. We developed a new methodology to estimate a representative commuting noise exposure. The methodology was put into practice for the Madrid subway because of all Spanish subway systems it covers the highest percentage of worker journeys (22.6%). The results of the application highlight that, for Madrid subway passengers, noise exposure level normalized to a nominal 8 hr (L(Ex,8h-cj) ) depends strongly on the type of train, the presence of squealing noise, and the public address audio system, ranging from 68.6 dBA to 72.8?dBA. These values play an important role in a more complete evaluation of a relationship between noise dose and worker health response.     

Risks of developing noise-induced hearing loss in employees of urban music clubs

Noise-induced hearing loss has previously been reported among rock musicians. This study sought to determine whether a hazard of noise-induced hearing loss exists for music club employees other than musicians themselves. Sound levels at eight live-music clubs were measured and symptoms of noise exposure in 31 music club employees were assessed by questionnaire. The average sound level at the various clubs during performances ranged from 94.9 to 106.7 dBA. The overall sound level average, including both performance and ambient levels, ranged from 91.9 to 99.8 dBA. Symptoms of noise exposure, such as tinnitus and subjective hearing loss, correlated with sound intensity. Only 16% reported regular use of hearing protection. We conclude that employees of music clubs are at substantial risk of developing Noise-Induced Hearing Loss, due to chronic noise exposure which consistently exceeded safe levels. Hearing protection is used much too infrequently. The development of hearing conservation programs for this large group of workers is essential. Am. J. Ind. Med. 31:75–79 © 1997 Wiley-Liss, Inc.