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.     

Respirable silica and noise exposures among stone processing workers in northern Thailand

Silica and noise are highly prevalent occupational exposures in the stone processing industry. Monitoring for silica and noise are expensive tasks that may be especially difficult to perform in low-resource settings, but exposure awareness is vital for protecting worker health. This study evaluated personal noise and silica measurements at a stone processing facility in northern Thailand to investigate the differing exposure potentials and risk for overexposure among the varying job categories. Our research team performed repeated personal noise and respirable silica measurements on 46 workers, over three separate workshifts for each of 46 workers. While 36.2% of noise measurements exceeded the recommended exposure limit of 85 dBA, only three silica measurements (2.4%) were above the threshold limit value (TLV) of 25 µg/m³. Self-reported personal protective equipment use was low, with only 27.5% of participants wearing hearing protection in noisy environments during their monitored shift and 29.7% of workers wearing respiratory protection during dusty portions of their shift. We identified a significant positive correlation between measured noise and silica levels (r = 0.54, p < 0.01), with stone loaders having the highest average noise (mean = 89 dBA, standard deviation = 4.9 dBA) and silica (geometric mean = 6.4 µg/m³, geometric standard deviation = 1.8) exposure levels. In a multivariate model, the stone loader job category was a significant predictor of exposure to detectable levels of respirable silica (p < 0.01). These results provide useful guidance regarding the need for noise and silica exposure interventions in order to reduce incidences of workplace disease in the stone processing industry.     

Noise exposure and permanent hearing loss of textile workers in Thailand

Hearing loss induced by noise exposure in a large scale textile mill (number of workers = 1,611) in Thailand was investigated on the basis of interviews, noise measurements, and audiometric tests. The frequency of subjective symptoms relating to noise exposure was higher in the weavers than among other mill workers and office workers. The average noise levels in the weaving sections and other sections were 101.3 +/- 2.7 dBA and 89.8 +/- 5.3 dBA, respectively. The results of the audiometric tests revealed the significantly higher noise-induced hearing loss among workers in the weaving section compared to other mill workers and office workers (P less than 0.01). Among weavers, hearing levels decreased with the longer years of work. Concerning personal noise protective devices, 38.6% of the weavers never used them. It was concluded that hearing loss status in the workers of the mill was serious. Improvements by means of integrated work organization activities were recommended.     

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.     

Noise exposure and hearing loss prevention programmes after 20 years of regulations in the United States

Objectives

To evaluate noise exposures and hearing loss prevention efforts in industries with relatively high rates of workers'' compensation claims for hearing loss.

Methods

Washington State workers'' compensation records were used to identify up to 10 companies in each of eight industries. Each company (n = 76) was evaluated by a management interview, employee personal noise dosimetry (n = 983), and employee interviews (n = 1557).

Results

Full‐shift average exposures were ⩾85 dBA for 50% of monitored employees, using Occupational Safety and Health Administration (OSHA) parameters with a 5 dB exchange rate (L_ave), but 74% were ⩾85 dBA using a 3 dB exchange rate (L_eq). Only 14% had L_ave ⩾90 dBA, but 42% had L_eq ⩾90 dBA. Most companies conducted noise measurements, but most kept no records, and consideration of noise controls was low in all industries. Hearing loss prevention programmes were commonly incomplete. Management interview scores (higher score = more complete programme) showed significant associations with percentage of employees having L_ave ⩾85 dBA and presence of a union (multiple linear regression; R² = 0.24). Overall, 62% of interviewed employees reported always using hearing protection when exposed. Protector use showed significant associations with percentage of employees specifically required to use protection, management score, and average employee time spent ⩾95 dBA (R² = 0.65).

Conclusions

The findings raise serious concerns about the adequacy of prevention, regulation, and enforcement strategies in the United States. The percentage of workers with excessive exposure was 1.5–3 times higher using a 3 dB exchange rate instead of the OSHA specified 5 dB exchange rate. Most companies gave limited or no attention to noise controls and relied primarily on hearing protection to prevent hearing loss; yet 38% of employees did not use protectors routinely. Protector use was highest when hearing loss prevention programmes were most complete, indicating that under‐use of protection was, in some substantial part, attributable to incomplete or inadequate company efforts.     

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.     

A faceoff with hazardous noise: Noise exposure and hearing threshold shifts of indoor hockey officials

Noise exposure and hearing thresholds of indoor hockey officials of the Western States Hockey League were measured to assess the impact of hockey game noise on hearing sensitivity. Twenty-nine hockey officials who officiated the league in an arena in southeastern Wyoming in October, November, and December 2014 participated in the study. Personal noise dosimetry was conducted to determine if officials were exposed to an equivalent sound pressure level greater than 85 dBA. Hearing thresholds were measured before and after hockey games to determine if a 10 dB or greater temporary threshold shift in hearing occurred. Pure-tone audiometry was conducted in both ears at 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. All noise exposures were greater than 85 dBA, with a mean personal noise exposure level of 93 dBA (SD = 2.2), providing 17.7% (SD = 6.3) of the officials' daily noise dose according to the OSHA criteria. Hearing threshold shifts of 10 dB or greater were observed in 86.2% (25/29) of officials, with 36% (9/25) of those threshold shifts equaling 15 dB or greater. The largest proportion of hearing threshold shifts occurred at 4000 Hz, comprising 35.7% of right ear shifts and 31.8% of left ear shifts. The threshold shifts between the pre- and post-game audiometry were statistically significant in the left ear at 500 (p=.019), 2000 (p=.0009), 3000 (p<.0001) and 4000 Hz (p=.0002), and in the right ear at 2000 (p=.0001), 3000 (p=.0001) and 4000 Hz (p<.0001), based on Wilcoxon-ranked sum analysis. Although not statistically significant at alpha = 0.05, logistic regression indicated that with each increase of one dB of equivalent sound pressure measured from personal noise dosimetry, the odds of a ≥ 10 dB TTS were increased in the left ear at 500 (OR=1.33, 95% CI 0.73-2.45), 3000 (OR=1.02, 95% CI 0.68-1.51), 4000 (OR=1.26, 95% CI 0.93-1.71) and 8000 Hz (OR=1.22, 95% CI 0.76-1.94) and in the right ear at 6000 (OR=1.03, 95% CI 0.14-7.84) and 8000 Hz (OR=1.29, 95% CI 0.12-13.83). These findings suggest that indoor hockey officials are exposed to hazardous levels of noise, experience temporary hearing loss after officiating games, and a hearing conservation program is warranted. Further temporary threshold shift research has the potential to identify officials of other sporting events that are at an increased risk of noise-induced hearing loss.     

Do ambient noise exposure levels predict hearing loss in a modern industrial cohort?

Background

Much of what is known about the exposure–response relationship between occupational noise exposures and hearing loss comes from cross‐sectional studies conducted before the widespread implementation of workplace hearing conservation programmes. Little is known about the current relationship of ambient noise exposure measurements to hearing loss risk.

Aim

To examine the relationship between rates of high frequency hearing loss and measured levels of noise exposure in a modern industrial workforce.

Methods

Ten‐year hearing loss rates were determined for 6217 employees of an aluminium manufacturing company. Industrial hygiene and human resources records allowed for reconstruction of individual noise exposures. Hearing loss rates were compared to ANSI 3.44 predictions based on age and noise exposure. Associations between hearing loss, noise exposure, and covariate risk factors were assessed using multivariate regression.

Results

Workers in higher ambient noise jobs tended to experience less high frequency hearing loss than co‐workers exposed at lower noise levels. This trend was also seen in stratified analyses of white males and non‐hunters. At higher noise exposure levels, the magnitude of hearing loss was less than predicted by ANSI 3.44 formulae. There was no indication that a healthy worker effect could explain these findings. The majority of 10 dB standard threshold shifts (STS) occurred in workers whose calculated ambient noise exposures were less than or equal to 85 dBA.

Conclusions

In this modern industrial cohort, hearing conservation efforts appear to be reducing hearing loss rates, especially at higher ambient noise levels. This could be related to differential use of hearing protection. The greatest burden of preventable occupational hearing loss was found in workers whose noise exposure averaged 85 dBA or less. To further reduce rates of occupational hearing loss, hearing conservation programmes may require innovative approaches targeting workers with noise exposures close to 85 dBA.     

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.     

Noise exposure, awareness, attitudes and use of hearing protection in a steel rolling mill in Nigeria

OBJECTIVES: To study exposure to noise, the attitudes and knowledge towards noise-induced hearing loss and the actual use of hearing protection in a steel rolling mill in Nigeria. METHODS: A structured questionnaire was administered to 116 randomly selected workers to collect information relating to their knowledge and attitudes towards hazardous occupational noise and preventative measures. Noise mapping of the factory was also carried out. RESULTS: Time weighted average noise levels were: administrative area 49 dBA, mechanic/maintenance workshop 72 dBA, mill floor 86 dBA and finishing stage 93 dBA. There was high awareness of the hazard of noise to hearing (93%) and of methods of prevention (92%) but only 27% possessed hearing protectors and only 28% of these stated that they used them all the time. CONCLUSION: While noise is recognized as a hazard, initiatives are required to increase use of effective preventative measures.     

Exposure to noise on board locomotives

Personal and area noise dosimetry measurements were taken in the cabs of leading and trailing locomotives on 48 trips, under winter and summer conditions, on 9 different routes. The mean equivalent sound level (L(EQ), 3 dB exchange rate, 50 dBA threshold) of the engineers and conductors was 84 dBA during winter and 88 dBA during summer. The corresponding time-weighted average levels (L(TWA), 5 dB exchange rate, 80 dBA threshold) were 80 and 84 dBA respectively. The L(EQ) of 56% of the engineers sampled was > or =85 dBA and of 13% was > or =90 dBA. Plots of L(EQ) time history show that under normal operating conditions L(EQ) reaches its steady-state value in about 3 hours. The mean noise levels in the trailing cabs were lower than the personal exposure levels of the engineers and conductors. The mean L(EQ) on the engineer and conductor sides was 80 dBA during winter, and 85 dBA during summer. Locomotive configuration has a significant effect on the noise levels in the trailing cab. The forward-backward configuration resulted in higher noise levels than the forward-forward configuration. Octave and one-third octave band spectra taken during a variety of locomotive operating conditions are presented. The octave band centered at 31.5 Hz contains nearly 46% of the acoustical energy, and those centered at and below 250 Hz contain nearly 99% of the acoustical energy. Wheel-rail interaction appears to be the predominant source of the low frequency noise. Recommendations for controlling exposure are made.     

An exploratory study of noise exposures in educational and private dental clinics

Exposures to noise and resulting noise-induced hearing loss (NIHL) are not well understood in the dental profession. Previous studies have focused primarily on practicing dental professionals, and have often evaluated hearing loss in the absence of adequate noise exposure assessment. This study was conducted to evaluate exposures among students and staff working in four clinics within a major U.S. university dental school, and to compare these exposures to those among dental professionals in a private general-practice clinic. We measured equivalent continuous average (L_EQ) noise exposure levels at 3.75-min intervals across a variety of procedures in the evaluated clinics, and also had participants complete a brief survey with questions on their experience and perceptions of noise exposure.

We collected 79 partial- or full-shift Time-Weighted Average (TWA) dosimetry measurements on 46 individuals. The mean 3.75-min interval L_EQ level was 63.6 ± 13.3 dBA, while the highest 3.75-min interval L_EQ was 103.5 dBA. Students from the dental school clinics had the highest variability in average exposure levels, while the pediatric clinic evaluated had the highest average and maximum exposures. Nearly 4% of standardized 8-hr TWA measurements exceeded the 85 dBA Recommended Exposure Limit established by the National Institute for Occupational Safety and Health. Concerns about the potential effects of dental noise on participants' hearing were significantly correlated with metrics of TWA noise exposure, as well as variability of exposure (as assessed by the SD of the 3.75-min L_EQ levels). Our results suggest that dental students and staff may have some risk of developing noise-induced hearing loss, particularly in pediatric clinical settings.     

A methodological approach for measuring personal exposure to noise]

A criterion is proposed for planning personal noise exposure surveys. For measurements taken at random over entire work shifts, the aim is to achieve preset confidence limits of the arithmetic mean of daily personal exposure (i.e., +/- 2 dBA or +/- 1 dBA). Five or six measurements are sufficient to estimate the standard deviation. By following simple rules to calculate the confidence limits for a population with unknown variance, it is possible to fix the number of measurements N with sufficient accuracy to achieve this goal. This number is a function of daily personal exposure variability. The choice of the confidence limits determines the accuracy of the personal noise exposure assessment, provided that it is the exponential mean of N measurements. This method allows the survey to be planned according to the desired accuracy of the final result. An example is provided of a survey carried out in a refractory brick factory, which shows that if the daily personal exposure range is 4-6 dBA, a 5-measurement survey is sufficient to achieve a +/- 2 dBA confidence interval, while 10-12 measurements are necessary to achieve a +/- 1 dBA confidence interval. If the range is 14-15 dBA the same results are achieved with 12-14 measurement in the first case and with about 50 in the second. The latter results shows that if the survey is stopped after 5 measurements, the probability of accepting a value of integrated personal noise exposure outside the N-integrated +/- 1 dBA range may reach 50%, mainly among groups of workers with greater variability in daily exposure.     

Noise Exposures of Rural Adolescents

Purpose: This project was conducted to characterize the noise exposure of adolescents living in rural and agricultural environments. Methods: From May to October, 25 adolescents ages 13 through 17, living either on a farm or a rural nonfarm, were enrolled in the study. Subjects received training on the correct operation and use of personal noise dosimeters and the proper way to record their daily tasks on activity cards. Subjects completed 4 days of self‐monitoring noise dosimetry, 2 days in the first round (May‐July) and 2 days in the second round (August‐October). In addition to dosimetry, subjects completed activity logs of their daily tasks. Results: The mean daily noise exposures of adolescents living on farms and in nonfarm rural homes were between 55.4 dBA (A‐weighted decibels) and 103.5 dBA, with 44% of the daily measurements greater than the National Institute of Occupational Safety and Health Recommended Exposure Level of 85 dBA. Task‐based analysis of noise exposures found that activities involving mechanized equipment resulted in the highest exposures, while activities in the home resulted in the lowest exposure. No particular demographic group had a statistically higher noise exposure; therefore, specific factors apart from activities and noise sources could not be identified as risk factors for exposure to hazardous noise levels. Conclusions: The results of this project indicate that rural adolescents complete a variety of activities and are exposed to noise sources with a broad range of decibel levels. While the exposures may change from day to day, there are occasions when exposure to noise exceeds the recommended levels.     

Hearing protector use in noise-exposed workers: a retrospective look at 1983

Although hearing protectors have been available for more than 60 years, little field surveillance has been done to assess their appropriate wear in noisy occupational environments. This study examined historical field survey data to determine whether workers use hearing protection when exposed to loud noise. Data from the 1981-83 NIOSH National Occupational Exposure Survey were analyzed to determine whether workers in noise greater than or equal to 85 dBA were using hearing protection. The study also looked at the effect of company personal protective equipment (PPE) policies on hearing protector compliance. This study found that, in 1981-83, an estimated 4.1 million industrial workers were exposed to noise greater than or equal to 85 dBA. Of these, 41% were wearing some form of hearing protection. This percentage varied from 79% of workers exposed in SIC 76 (Miscellaneous Repair Service) to less than 1% in Communications (SIC 48), Wholesale Trade Nondurable Goods (SIC 51), and Automotive Dealers & Service Stations (SIC 55). Whether an establishment had a written policy on wearing PPE seemed to make no difference, because there appeared to be no tie between the percentage of workers wearing of hearing protection and presence of a PPE policy.     

某客车制造企业个体噪声暴露水平的 职业危害风险评估

目的 监测某客车制造企业工人个体噪声水平,评估该企业工人由于噪声暴露所致的听力损失以及噪声性耳聋风险水平。方法 对某客车制造企业35名工人进行个体噪声监测,运用噪声职业病危害风险管理指南法对个体噪声8 h工作日等效声级（L EX,8h）≥80 dB(A)的岗位进行噪声风险评估。结果 噪声强度≥85 dB(A)的工人有21名,占60%（21/35）;预测暴露年数≤30年时,发生高频听阈损失和职业性噪声聋风险等级最高的是铸造车间打磨工和涂装车间重抛光工,为较高风险;暴露年数>30年时,发生高频听阈损失和职业性噪声聋风险等级最高的是涂装车间重抛光工,为高风险。结论 该企业噪声危害较为严重,应采取改进工艺措施降低噪声水平,加强个人防护,建立听力保护计划等方案保护工人听力健康。     

Changes over time in audiometric thresholds in a group of automobile stamping and assembly workers with a hearing conservation program

Noise induced hearing loss (NIHL) is among the 10 leading occupational diseases, afflicting between 7.4 and 10.2 million people who work in noise above 85 dBA. Although mandatory hearing conservation programs (HCPs) have been in effect since 1972, this problem persists, as hearing protectors are not consistently used by workers, or may not attenuate to manufacturer's estimates in real world conditions. In this study, information from noise and hearing protection use measurements taken at an automobile assembly plant were used to construct average lifetime noise exposure and hearing protection compliance estimates for use in modeling to predict both total hearing loss and onset of two accepted definitions of hearing loss. There were 301 males and females in this cohort; their mean age was 42.6 (7.2) years, and mean tenure was 14.3 (3.5) years. Average length of follow-up was 14.0 years. There were 16 members of this cohort who had hearing loss at the speech frequencies (defined as an average hearing level > or = 25 dB at 500, 1000, and 2000 Hz). In cross-sectional multivariate analyses, years of employment, male gender, and proportion of time wearing hearing protection were the factors most associated with hearing loss at the average of 2000, 3000, and 4000 Hz (p < 0.0001) controlling for age, transfer status (as a surrogate for previous noise exposure), race, and lifetime average noise exposure. The most consistent predictor of hearing loss in both univariate and multivariate analyses was percentage of time having used hearing protection during the workers' tenure.     

Noise at sea: Characterization of extended shift noise exposures among U.S. Navy aircraft carrier support personnel

The purpose of this investigation was to characterize 12-hr on-duty, 12-hr off-duty, and 24-hr noise exposures among U.S. Navy aircraft carrier support personnel. Noise dosimetry samples were collected for 47 aircraft carrier support personnel while at sea during airwing carrier qualifications. L_eq measurements during 12-hr on-duty, 12-hr off-duty, and over 24-hr periods were compared to Threshold Limit Values. Four similar exposure groups (SEGs) were created based upon departmental assignment and similarity of work tasks: (1) Administration/Religious Ministries/Legal/Training, (2) Combat Systems/Operations, (3) Medical/Dental, and (4) Supply. Equivalent sound level (Leq) measurements in decibels “A” weighted (dBA) were compared to determine significant differences between each group according to 12-hr on-duty, 12-hr off-duty, and 24-hr periods. Mean 24-hr noise levels ranged from 69–88 dBA with 22% exceeding the 80 dBA Threshold Limit Value. Twelve-hr on-duty noise levels ranged from 71–90 dBA with 17% exceeding the 83 dBA 12-hr on-duty Threshold Limit Value. Twelve-hr off-duty noise exposure ranged from 68–84 dBA with 95% exceeding the 70 dBA American Conference of Governmental Industrial Hygienists threshold classified as effective quiet to allow for temporary threshold shift recovery. Welch Analysis of Variance and Dunnett T3 post hoc tests revealed SEG 2 had significantly higher 24-hr noise exposures than SEG 3 (p?=?0.019) and SEG 4 (p?=?0.045). SEG 2 had significantly higher 12-hr on-duty noise exposure than SEG 3 (p?=?0.030). One Way Analysis of Variance revealed no significant differences between 12-hr off-duty noise exposures according to SEG (p = .096). Some aircraft carrier support personnel had 12-hr on-duty and 24-hr noise exposures exceeding Threshold Limit Values with a large proportion exceeding the 70 dBA effective quiet limit during 12-hr off-duty periods. Results suggest personnel that are typically considered low risk for hazardous noise exposure (<85 dBA) during 8-hr shifts may have a greater risk of noise exposure when considering full 12-hr and 24-hr shifts when working and living in close proximity.     

Comparison of NIOSH noise criteria and OSHA hearing conservation criteria

BACKGROUND: This study was conducted to compare noise exposure measurements based on the recently revised noise exposure criteria recommended by the U.S. National Institute for Occupational Safety and Health (NIOSH) and the current U.S. Occupational Safety and Health Administration (OSHA) Hearing Conservation Amendment to the occupational noise standard. METHODS: Daily 8-hour time-weighted average (TWA) personal noise exposures were obtained for 61 workers using dosimeters set simultaneously to the NIOSH and OSHA Hearing Conservation Amendment (OSHA-HCA) criteria. A variety of work groups with the potential for noise exposure were evaluated as a part of this investigation. RESULTS: Noise dose based on the NIOSH criteria was higher than the corresponding OSHA-HCA noise dose with differences in noise exposures measured under the two criteria equal to 6.6 dBA. Should the new NIOSH recommendation on noise measurement be adopted as standard, the number of workers to be enrolled in a hearing loss prevention program was estimated to increase by 2. 7-fold from 23% to 75% of the study population. CONCLUSIONS: The results of this study indicate that if the NIOSH criteria are to be adopted as an OSHA standard, there is likely to be a substantial increase in the number of workers in hearing conservation programs.