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1.
The purpose of this investigation was to characterize noise levels in spaces designated as “effective quiet” areas on a U.S. Navy aircraft carrier. Noise dosimetry samples were collected in 15 designated spaces, representing 15 noise measurements, while at-sea during airwing carrier qualifications. Equivalent sound level (L eq) measurements were collected during flight operations (L eq (flt ops)), non-flight operations (L eq (non-flt ops)), and over 24-hr periods (L eq (24-hr)). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH ®) Threshold Limit Value (TLV ®) for “effective quiet” areas intended for temporary threshold shift recovery when personnel live and work in a potentially noise hazardous environment for periods greater than 24?hr. The monitored areas were selected based on personnel occupancy/use during off-duty time periods. Areas were classified by either (1) leisure areas that included mess (eating areas), gyms, lounges, an internet cafe, and the fantail social area or (2) berthing (sleeping) areas. The L eq measurements in decibels “A” weighted (dBA) were compared to determine significant differences between L eq (flt ops), L eq (non-flt ops), and L eq (24-hr) and were compared between leisure area and berthing area. Measured noise levels according to time period ranged as follows: (1) L eq (24-hr): 70.8–105.4 dBA; (2) L eq (flt ops): 70–101.2 dBA; and (3) L eq (non-flt ops): 39.4–104.6 dBA. All area measurements over the 24-hr period and during flight operations and 46.7% of the areas during the non-flight operation time period exceeded the “effective quiet” 70 dBA ACGIH TLV. Mean L eqs were 15 dBA higher during flight operations compared to non-flight operations in “effective quiet” areas ( p?=?0.001). The L eqs in leisure areas were significantly higher than berthing areas by approximately 21 dBA during non-flight operation periods ( p?=?0.001). Results suggest noise levels in “effective quiet” areas frequented by aircraft carrier personnel during off-duty hours when at-sea may inhibit auditory recovery from occupational noise exposures that occur on-duty. 相似文献
3.
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. 相似文献
4.
IntroductionIn 2006, the World Health Organization Framework Convention on Tobacco Control became effective in mainland China. In 2007, advocacy on voluntary smoking bans in restaurants was initiated in Beijing, and in 2008 the Beijing government implemented a smoking regulation, requiring big restaurants to prohibit or restrict smoking. ObjectivesTo evaluate the efficacy of different smoking policies adopted by Beijing restaurants and bars from 2006 to 2010. MethodsThe study conducted field observations of patron smoking behavior and monitored fine particulate matter from secondhand smoke (SHS PM) from 91, 85, 94 and 79 Beijing restaurants and bars in 2006, 2007, 2008 and 2010, respectively, during peak-patronage times, with overlaps of venues during each two years. Area nicotine sampling during peak patronage times and servers’ personal nicotine sampling during their working shifts were also conducted in 2010. ResultsSmoking was nominally prohibited or restricted in 18% of restaurants and bars monitored in 2006, in 11% of venues in 2007, in 83% of venues in 2008, and in 69% of venues in 2010. However, smoking was observed in more than 40% of the nominal nonsmoking venues/sections in 2008 and 2010. The median of observed patron active smoker density (ASD) was 0.24, 0.27, 0.00 and 0.10 active smokers per 100 m 3 in 2006, 2007, 2008 and 2010, respectively. The median of SHS PM concentrations was 53, 83, 18 and 27 μg/m 3, respectively. In 2010, both the median SHS PM and air nicotine concentrations in designated nonsmoking sections were about 40% of those in designated smoking sections, according to simultaneous sampling in both sections. Servers’ personal exposure to air nicotine was quite similar in venues with different nominal smoking policies. In the 15 venues followed from 2006 to 2010, SHS PM concentrations changed randomly from 2006 to 2007, decreased in most venues in 2008, and then increased to some extent in 2010. ConclusionVoluntary smoking policy is rarely adopted and cannot protect people from SHS exposure in restaurants and bars. The 2008 Beijing governmental smoking regulation failed to significantly reduce SHS exposure shortly or two years after its implementation. Restricting smoking to designated sections cannot eliminate SHS exposure. 相似文献
5.
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. 相似文献
6.
Exposure to environmental noise from traffic is common in urban areas and has been linked to increased risks of adverse health effects including cardiovascular disease. Because traffic sources also produce air pollutants that increase the risk of cardiovascular morbidity, associations between traffic exposures and health outcomes may involve confounding and/or synergisms between air pollution and noise. While prior studies have characterized intraurban spatial variation in air pollution in New York City (NYC), limited data exists on the levels and spatial variation in noise levels. We measured 1-week equivalent continuous sound pressure levels (L eq) at 56 sites during the fall of 2012 across NYC locations with varying traffic intensity and building density that are routinely monitored for combustion-related air pollutants. We evaluated correlations among several noise metrics used to characterize noise exposures, including L eq during different time periods (night, day, weekday, weekend), L dn (day-night noise), and measures of intermittent noise defined as the ratio of peak levels to median and background levels. We also examined correlations between sound pressure levels and co-located simultaneous measures of nitric oxide (NO), nitrogen dioxide (NO 2), fine particulate matter (PM 2.5), and black carbon (BC) as well as estimates of traffic and building density around the monitoring sites. Noise levels varied widely across the 56 monitoring sites; 1-week L eq varied by 21.6 dBA (range 59.1–80.7 dBA) with the highest levels observed during the weekday, daytime hours. Indices of average noise were well correlated with each other ( r > 0.83), while indices of intermittent noise were not well correlated with average noise levels ( r < 0.41). One-week L eq correlated well with NO, NO 2, and EC levels ( r = 0.61 to 0.68) and less so with PM 2.5 levels ( r = 0.45). We observed associations between 1-week noise levels and traffic intensity within 100 m of the monitoring sites ( r = 0.58). The high levels of noise observed in NYC often exceed recommended guidelines for outdoor and personal exposures, suggesting unhealthy levels in many locations. Associations between noise, traffic, and combustion air pollutants suggest the possibility for confounding and/or synergism in intraurban epidemiological studies of traffic-related health effects. The different spatial pattern of intermittent noise compared to average noise level may suggest different sources. 相似文献
7.
ObjectivesTo evaluate noise exposures and hearing loss prevention efforts in industries with relatively high rates of workers'' compensation claims for hearing loss. MethodsWashington 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). ResultsFull‐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; R 2 = 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 (R 2 = 0.65). ConclusionsThe 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. 相似文献
9.
ABSTRACT A pilot project was conducted to evaluate occupational noise exposures of three families living and working on farms in Northwest Ohio. Noise exposures were measured continuously for 7 consecutive days for each participant for 1 week each during planting, growing, and harvesting seasons. The dosimeters were programmed to evaluate noise exposures using both the Occupational Safety and Health Administration (OSHA) action level and the National Institute for Occupational Safety and Health (NIOSH)/American Conference of Governmental Industrial Hygienists (ACGIH) guidelines. One family was evaluated per year and a total of nine family members (six adults and three children) participated. Adult noise exposures for on-farm activities (occupational exposures) ranged from 46.1 to 89.6 decibels on the A-weighted scale (dBA) as an 8-hour time-weighted average (8HR TWA) using the OSHA action level and from 62.6 to 92.1 dBA 8HR TWA using the NIOSH/ACGIH guidelines. Occupational noise exposures for the children ranged from 15.4 to 81.2 dBA 8HR TWA using the OSHA action level and from 42.4 to 85.5 dBA 8HR TWA using the NIOSH/ACGIH guidelines. Six of 45 exposures among the adults and none of the 11 exposures among the children exceeded the OSHA action level. In addition, 10 of 45 exposures among the adults and 1 of 11 exposures among the children exceeded the NIOSH/ACGIH guidelines. The results of this pilot project indicate noise exposures among farm families can exceed recommended levels. 相似文献
10.
Governments all over the world have enacted environmental noise directives and noise control ordinances/acts to protect tranquility in residential areas. However, there is a lack of literature on the evaluation of whether the Acceptable Noise Levels (ANLs) stipulated in the directive/ordinance/act are actually achievable. The study aimed at measuring outdoor environmental noise levels in Hong Kong and identifying whether the measured noise levels are lower than the stipulated ANLs at 20 categories of residential areas. Data were gathered from a territory-wide noise survey. Outdoor noise measurements were conducted at 203 residential premises in urban areas, low-density residential areas, rural areas, and other areas. In total, 366 daytime hourly Leq outdoor noise levels, 362 nighttime hourly Leq outdoor noise levels, and 20 sets of daily, that is, 24 Leq,1-h outdoor noise levels were recorded. The mean daytime Leq,1-h values ranged 54.4-70.8 dBA, while the mean nighttime Leq,1-h values ranged 52.6-67.9 dBA. When the measured noise levels were compared with the stipulated ANLs, only three out of the 20 categories of areas had outdoor noise levels below ANLs during daytime. All other areas (and all areas during nighttime) were found to have outdoor noise levels at or above ANLs. 相似文献
11.
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. 相似文献
12.
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. 相似文献
13.
Forty-two noise exposures and 164 whole-body (WBV) and hand-arm (HAV) vibration exposures were collected from 43 forestry workers in six trades employed by two forestry companies. Data were collected on 10 days over 8 weeks during various felling, logging, and log handling operations. Up to 5 volunteers were monitored for noise and vibration daily using datalogging noise dosimeters, which provided daily time-weighted averages (TWAs) and 1-min averages; and a precision sound level meter equipped to measure human vibration, which provided triaxial HAV and WBV event-weighted averages (AEQS). Workers completed a short questionnaire throughout the workday detailing the timing and number of tasks performed and equipment used. Substantial overexposures to noise and vibration were seen; for example, 60% of Occupational Safety and Health Administration (OSHA) TWAs and 83% of National Institute for Occupational Safety and Health (NIOSH) noise TWAs exceeded 85 dBA, 33-53% of the axis-specific HAV AEQS exceeded the 8-hour American Conference of Governmental Industrial Hygienists' HAV threshold limit value, and 34% of all summary weighted WBV AEQS exceeded the Commission of the European Communities' 8-hour exposure limit. The mean for 99 WBV summary weighted AEQ was 3.53 +/- 7.12 m/sec2, whereas the mean for 65 HAV summary weighted AEQ was 5.45 +/- 5.25 m/sec2. The mean OSHA TWA was 86.1 +/- 6.2 dBA, whereas the mean NIOSH TWA was 90.2 +/- 5.1 dBA. The task and tool with the highest exposure levels were unbelling chokers on landings and chain saws (noise), log processing and frontend loaders (WBV), and notching stumps and chain saws (HAV). An internal validation substudy indicated excellent agreement between worker-reported and researcher-documented tasks and tools. 相似文献
14.
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 LEQ level was 63.6 ± 13.3 dBA, while the highest 3.75-min interval LEQ 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 LEQ levels). Our results suggest that dental students and staff may have some risk of developing noise-induced hearing loss, particularly in pediatric clinical settings. 相似文献
15.
Noise is a pervasive workplace hazard that varies spatially and temporally. The cost of direct-reading instruments for noise hampers their use in a network. The objectives for this work were to: (1) develop an inexpensive noise sensor (<$100) that measures A-weighted sound pressure levels within ±2 dBA of a Type 2 sound level meter (SLM; ~$1,800); and (2) evaluate 50 noise sensors for use in an inexpensive sensor network. The inexpensive noise sensor consists of an electret condenser microphone, an amplifier circuit, and a microcontroller with a small form factor (28 mm by 47 mm by 9 mm) than can be operated as a stand-alone unit. Laboratory tests were conducted to evaluate 50 of the new sensors at 5 sound levels: (1) ambient sound in a quiet office; (2) 3 pink noise test signals from 65–85 dBA in 10 dBA increments; and (3) 94 dBA using a SLM calibrator. Ninety-four percent of the noise sensors (n = 46) were within ±2 dBA of the SLM for sound levels from 65–94 dBA. As sound level increased, bias decreased, ranging from 18.3% in the quiet office to 0.48% at 94 dBA. Overall bias of the sensors was 0.83% across the 75 dBA to 94 dBA range. These sensors are available for a variety of uses and can be customized for many applications, including incorporation into a stationary sensor network for continuous monitoring of noise in manufacturing environments. 相似文献
16.
Due to the transposition of the EU Directive 2003/10/EC into Irish Law, the entertainment sector was obligated to comply with the requirements of the Safety, Health and Welfare at Work (General Application) Regulations 2007, Chapter 1 Part 5: Control of Noise at Work since February 2008. Compliance with the Noise Regulations was examined in 9 nightclubs in Ireland. The typical daily noise exposure of 19 bar employees was measured using 2 logging dosimeters and a Type 1 fixed position sound level meter. Physical site inspections identified nightclub noise control measures. Interviews and questionnaires were used to assess the managers and employees awareness of the noise legislation. The average bar employee daily noise exposure (L(EX, 8h)) was 92 dBA, almost 4 times more than the accepted legal limit. None of the venues examined were fully compliant with the requirements of the 2007 Noise Regulations, and awareness of this legislation was limited. 相似文献
17.
Three hundred thirty-eight noise exposure samples were collected from 133 construction workers employed in 4 construction trades: carpenters, laborers, ironworkers, and operating engineers. Four sites using a variety of construction techniques were sampled at least 12 times on a randomly chosen date over a 22-week period. Up to 10 volunteer workers were sampled for an entire work shift on each sampling day using datalogging noise dosimeters, which recorded both daily time-weighted averages (TWAs) and 1-min averages. Workers also completed a questionnaire throughout the workday detailing the tasks performed and tools used throughout the day. Regression models identified work characteristics associated with elevated exposure levels. Comparisons were made between exposures measured using the Occupational Safety and Health Administration (OSHA) exposure metric and the 1996 draft National Institute for Occupational Safety and Health/International Organization for Standardization (NIOSH/ISO) metric to examine the effects of differing exchange rates and instrument response times on construction noise exposures. The mean OSHA TWA for 338 samples was 82.8 dBA +/- 6.8 dBA, whereas the mean NIOSH/ISO TWA for 174 samples was 89.7 dBA +/- 6.0 dBA. Forty percent of OSHA TWAs exceeded 85 dBA, and 13% exceeded 90 dBA, the OSHA permissible exposure limit. The tasks and tools associated with the highest exposure levels were those involving pneumatically operated tools and heavy equipment. Trade was a poor predictor of noise exposure; construction method, stage of construction, and work tasks and tools used were found to be better exposure predictors. An internal validation substudy indicated excellent agreement between worker self-reporting and researcher observation. These data provide substantial documentation that construction workers in several key trades are frequently exposed to noise levels that have been associated with hearing loss, and demonstrate the need for targeted noise reduction efforts and comprehensive hearing conservation programs in the industry. 相似文献
18.
Secondhand smoke (SHS) contains more than 50 carcinogens. SHS exposure is responsible for an estimated 3,000 lung cancer deaths and more than 35,000 coronary heart disease deaths among never smokers in the United States each year, and for lower respiratory infections, asthma, sudden infant death syndrome, and chronic ear infections among children. Even short-term exposures to SHS, such as those that might be experienced by a patron in a restaurant or bar that allows smoking, can increase the risk of experiencing an acute cardiovascular event. Although population-based data indicate declining SHS exposure in the United States over time, SHS exposure remains a common but preventable public health hazard. Policies requiring smoke-free environments are the most effective method of reducing SHS exposure. Effective July 24, 2003, New York implemented a comprehensive state law requiring almost all indoor workplaces and public places (e.g., restaurants, bars, and other hospitality venues) to be smoke-free. This report describes an assessment of changes in indoor air quality that occurred in 20 hospitality venues in western New York where smoking or indirect SHS exposure from an adjoining room was observed at baseline. The findings indicate that, on average, levels of respirable suspended particles (RSPs), an accepted marker for SHS levels, decreased 84% in these venues after the law took effect. Comprehensive clean indoor air policies can rapidly and effectively reduce SHS exposure in hospitality venues. 相似文献
19.
Only option E reduced the overall A-weighted level to less than 90 dBA, and in fact, it reduced it to less than 85 dBA, the level at which OSHA requires a hearing conservation program. Thus, a worker could be exposed to the resulting sound level using option E for up to eight hours. The results of all of the other measures required limited exposure, according to Table 1. Untreated (and without hearing protection), the worker could be exposed to the 112-dBA sound level for only about 15 minutes during the day. Option B would allow the employee to be exposed to the 105-dBA sound level for one hour; Option C of 98 dBA for about 2 hours; and Option D of 91 dBA for about 7 hours. These times assume the worker is not exposed to other high noise levels; otherwise, these have to be accounted for, as well. The best solution depends on how long the parts tumbler is in operation and whether barriers or enclosures are practical. Other solutions may exist, as well. It's always best to have a qualified acoustician evaluate the problem and make recommendations. 相似文献
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