A trial measurement of individual noise exposure by time-zone in a day (author's transl)]

Noise has been measured usually for a particular source or place and not for each individual exposed. It has been thought to be of great significance if individual noise exposure is recorded in various kinds of noise environment and auditory effects of noise on each individual can be discussed. The present study, having each of examinees carry 10-Channel Noise Exposure Meter with him, intended to know about dose or equivalent sound level (Leq) of individual nois exposure for a whole day and for each of eight time-zones in a day. The examinees were 12 male married workers in a factory manufacturing electronic machines in Kawasaki City, Kanagawa Prefecture, Japan. They were divided into two groups; those who were working in a noisy workshop (Group N, 8 workers) and those who were working in a less noisy workshop (Group N-N 4 workers). Time-zones were categorized as follows: (a) time from rising to leaving home for the place of work, (b) commuting time in the forenoon, (c) working time in the forenoon, (d) noon recess time, (e) working time in the afternoon, (f) commuting time in the afternoon, (g) time from returning home to going to bed, and (h) sleeping time. Leq (c) and Leq (b) were highest and Leq (h) was lowest for Group N among the eight Leq values in the day, while Leq (b) and Leq (f) were highest for Group N-N. Statistically significant differences of Leq for each time-zone between the two groups were found in Leq (c), Leq (d) and Leq (e), whose energy average sound levels for Group N and Group N-N were 84.2 and 59.4 dB, 72.7 and 61.4 dB, and 85.5 and 61.4 dBrespectively. Energy average equivalent sound levels of Leq (24) were 81.0 dB for Group N and 66.7 dB for Group N-N. Leq (24) for Group N were primarily determined by the noise exposure in the working time (c and e), while those for Group N-N by that in the commuting time (b and f). Practical disadvantages in the course of individual application of 10-Channel Noise Exposure Meter were also pointed out. It was shown that it is possible individually to measure the noise exposure dose for each time-zone in a day or daily noise exposure pattern, and the noise exposure dose over 24-hour. It may be recommended that many typical noise exposure patterns and 24-hour noise exposure doses for each of the groups classified by sex, age, kind of job, kind of commuting methods, kind of residential area of residential area and so forth should be surveyed further, which will be useful for estimating the auditory effects of noise on a population. Also, the relationships between Leq and such effects as annoyance or interference with daily activities should be examined to ease the measurement of noise.     

Noise characterization of “effective quiet” areas on a U.S. Navy aircraft carrier

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.     

Spatial Variation in Environmental Noise and Air Pollution in New York City

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 (NO₂), 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, NO₂, 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.     

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.     

Individual Daytime Noise Exposure during Routine Activities and Heart Rate Variability in Adults: A Repeated Measures Study

Background: Epidemiological studies have demonstrated associations between noise exposure and cardiovascular events. However, there have been few studies of possible underlying mechanisms.Objectives: We examined the association between individual daytime noise exposure and heart rate variability (HRV).Methods: In a prospective panel study in Augsburg, Germany (March 2007–December 2008), 110 individuals participated in 326 electrocardiogram recordings with a mean duration of 6 hr. Five-minute averages of heart rate (HR) and HRV parameters were determined. Individual noise exposure was measured as A-weighted equivalent continuous sound pressure levels (L_eq). Effects were estimated using additive mixed models adjusted for long- and short-term time trends and physical activity. Due to nonlinear exposure–response functions, we performed piecewise linear analyses with a cut-off point at 65 dB(A).Results: Concurrent increases of 5dB(A) in L_eq < 65dB(A) were associated with increases in HR (percent change of mean value: 1.48%; 95% CI: 1.37, 1.60%) and the ratio of low-frequency (LF) to high-frequency (HF) power (4.89%; 95% CI: 3.48, 6.32%), and with decreases in LF (–3.77%; 95% CI: –5.49, –2.02%) and HF (–8.56%; 95% CI: –10.31, –6.78%) power. Standard deviation of normal-to-normal intervals (SDNN) was positively associated with concurrent noise < 65dB(A) (5.74%; 95% CI: 5.13, 6.36) but negatively associated with noise lagged by 5–15 min (–0.53% to –0.69%). Associations with cardiac function were less pronounced for noise ≥ 65dB(A), with some in opposite directions from associations with noise < 65dB(A). Concurrent associations were modified by sex and age.Conclusions: Individual daytime noise exposure was associated with immediate changes in HRV, suggesting a possible mechanism linking noise to cardiovascular risk. Noise at lower levels may have health consequences beyond those resulting from “fight-or-flight” responses to high levels of noise.     

Life span and organ pathology in rats after life-long noise exposure

The role of ambient sound level in longevity, cause of death, and incidence of disease was investigated in rats. Two hundred twenty-seven rats (154 Sprague-Dawley (N), 73 spontaneously hypertensive Wistar (SH)), were housed in three sound isolated boxes and subjected to controlled acoustic milieus from approximately three months of age until their natural death. Thirty-nine of the N rats were kept as external controls in a regular animal room. In one of the boxes, no noise was introduced (control). In the other two, the rats were exposed, respectively, to a frequency-modulated, chopped noise with an equivalent level of 80 dB L_eq and 100 dB L_eq, ten hours daily. It was found that the SH animals had a shorter life span and a higher incidence of cardiovascular disease than the N rats but a lower rate of malignant tumors. No measurable effects on life span or total incidence of disease were seen. Minor differences in incidence of various disease entities were observed but were not consistent across groups. The results do not support the hypothesis that physical sound environment represents a significant cause of somatic disease.     

Are the noise levels acceptable in a built environment like Hong Kong?

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 L_eq outdoor noise levels, 362 nighttime hourly L_eq outdoor noise levels, and 20 sets of daily, that is, 24 L_eq,1-h outdoor noise levels were recorded. The mean daytime L_eq,1-h values ranged 54.4-70.8 dBA, while the mean nighttime L_eq,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.     

Industrie- und Gewerbel?rm

Zusammenfassung In der Umgebung von fünf Industrie- und Gewerbeanlagen wurden die Lärmimmissionen gemessen und mittels schriftlicher Befragung die Auswirkungen derselben auf die dort wohnenden Menschen erfasst.Es zeigte sich, dass gehäufte Störungen und Reaktionen bei Betriebslärmimmissionen tagsüber ab einemL _eq von ungefähr 50 dB(A) auftreten und nachts ab einemL _eq von ungefähr 40 dB(A).

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Noise immissions of industrial plants

Summary In the surroundings of five industrial plants noise immissions were measured, and people were asked by questionnaire about the effects caused by noise.The results show that increased disturbances and reactions to industrial noise immissions occur at daytime with anL _eq of about 50 dB(A) and at nighttime with anL _eq of about 40 dB(A).

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Immissions de bruit des entreprises industrielles

Résumé Dans les environs de cinq entreprises industrielles, on a mesuré les immissions de bruit, et les habitants ont été questionnés sur les effets causés par le bruit.Les résultats montrent que les troubles et réactions augmentent à partir d'une valeurL _eq située environ à 50 dB(A) pour le jour et à 40 dB(A) environ pour la nuit.

     

Association between Ambient Noise Exposure and School Performance of Children Living in An Urban Area: A Cross-Sectional Population-Based Study

Most of the studies investigating the effects of the external noise on children’s school performance have concerned pupils in schools exposed to high levels due to aircraft or freeway traffic noise. However, little is known about the consequences of the chronic ambient noise exposure at a level commonly encountered in residential urban areas. This study aimed to assess the relationship between the school performance of 8- to 9-year-old-children living in an urban environment and their chronic ambient noise exposure at home and at school. The children’s school performances on the national standardized assessment test in French and mathematics were compared with the environmental noise levels. Children’s exposure to ambient noise was calculated in front of their bedrooms (L_den) and schools (L_Aeq,day) using noise prediction modeling. Questionnaires were distributed to the families to collect potential confounding factors. Among the 746 respondent children, 586 were included in multilevel analyses. On average, the L_Aeq,day at school was 51.5 dB (SD= 4.5 dB; range = 38–58 dB) and the outdoor L_den at home was 56.4 dB (SD= 4.4 dB; range = 44–69 dB). L_Aeq,day at school was associated with impaired mathematics score (p = 0.02) or impaired French score (p = 0.01). For a + 10 dB gap, the French and mathematics scores were on average lower by about 5.5 points. L_den at home was significantly associated with impaired French performance when considered alone (p < 10⁻³) and was borderline significant when the combined home-school exposure was considered (p = 0.06). The magnitude of the observed effect on school performance may appear modest, but should be considered in light of the number of people who are potentially chronically exposed to similar environmental noise levels.     

The spatial relationship between traffic-generated air pollution and noise in 2 US cities

Traffic-generated air pollution and noise have both been linked to cardiovascular morbidity. Since traffic is a shared source, there is potential for correlated exposures that may lead to confounding in epidemiologic studies. As part of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), 2-week NO and NO₂ concentrations were measured at up to 105 locations, selected primarily to characterize gradients near major roads, in each of 9 US communities. We measured 5-min A-weighted equivalent continuous sound pressure levels (L_eq) and ultrafine particle (UFP) counts at a subset of these NO/NO₂ monitoring locations in Chicago, IL (N=69 in December 2006; N=36 in April 2007) and Riverside County, CA (N=46 in April 2007). L_eq and UFP were measured during non-“rush hour” periods (10:00–16:00) to maximize comparability between measurements. We evaluated roadway proximity exposure surrogates in relation to the measured levels, estimated noise–air pollution correlation coefficients, and evaluated the impact of regional-scale pollution gradients, wind direction, and roadway proximity on the correlations. Five-minute L_eq measurements in December 2006 and April 2007 were highly correlated (r=0.84), and measurements made at different times of day were similar (coefficients of variation: 0.5–13%), indicating that 5-min measurements are representative of long-term L_eq. Binary and continuous roadway proximity metrics characterized L_eq as well or better than NO or NO₂. We found strong regional-scale gradients in NO and NO₂, particularly in Chicago, but only weak regional-scale gradients in L_eq and UFP. L_eq was most consistently correlated with NO, but the correlations were moderate (0.20–0.60). After removing the influence of regional-scale gradients the correlations generally increased (L_eq–NO: r=0.49–0.62), and correlations downwind of major roads (L_eq–NO: r=0.53–0.74) were consistently higher than those upwind (0.35–0.65). There was not a consistent effect of roadway proximity on the correlations. In conclusion, roadway proximity variables are not unique exposure surrogates in studies of endpoints hypothesized to be related to both air pollution and noise. Moderate correlations between traffic-generated air pollution and noise suggest the possibility of confounding, which might be minimized by considering regional pollution gradients and/or prevailing wind direction(s) in epidemiologic studies.     

Diurnal variability of transportation noise exposure and cardiovascular mortality: A nationwide cohort study from Switzerland

Background

Most epidemiological noise studies consider 24?h average noise exposure levels. Our aim was to exploratively analyze the impact of noise exposure at different time windows during day and night on cardiovascular mortality.

H?rsch?den in der Industrie

Zusammenfassung Untersuchungen der vorübergehenden Verschiebung der Hörschwelle werden als Modellsituation für die Erforschung der dauernden Hörverluste angewendet. Die vorübergehende Verschiebung der Hörschwelle durch Schallreize von hohen Intensitäten von mehr als 90 dB ist um ein Mehrfaches grösser als diejenige durch niedrige Intensitäten. Sie ist proportional der Expositionsdauer. Ihr Abklingen dauert 10mal länger als die Dauer des verursachenden Schallreizes. Die vorübergehende Verschiebung der Hörschwelle wird durch alternierende Lärm- und Ruheperioden um die Hälfte geringer als durch einen kontinuierlichen Lärm der gleichen akustischen Energie. — Ein gleichbleibender Lärm soll den Grenzwert von 90 dB(A) nicht erreichen. Eine nicht-kontinuierliche Lärmsituation ist mittels des äquivalenten Dauerschallpegels L_eq zu bewerten, sie soll den L_eq-Wert von 90 dB(A) nicht erreichen. Das Risiko der Gehörbeeinträchtigung durch einen übermässigen Lärm kann mittels des L_eq und der Expositionsdauer in Jahren eingeschätzt werden. Erreicht oder überschreitet eine Lärmsituation den Grenzwert, sind Schutzmassnahmen zu treffen. Durch technische Massnahmen kann der Lärm an der Quelle und bei der Ausbreitung reduziert werden. Durch organisatorische Massnahmen kann die Expositionsdauer gekürzt werden. Die Hörschutzgeräte bieten die letzte Verhütungsmöglichkeit, doch sie sollen keinesfalls die andern Schutzmassnahmen ersetzen.

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Hearing damage in industry

Summary Test on temporary displacement of the hearing threshold are used as model situations for studies on permanent loss of hearing. Temporary displacement of the hearing threshold by means of sounds of high intensity of more than 90 dB is several times as big than that caused by low intensities. This displacement is proportional to the duration of the exposure. Its decrease lasts ten times as long as the sound having provoked the displacement.The temporary displacement of the hearing threshold following alternating periods of noise and quiet represents only half of the displacement caused by a continuous noise of the same acoustical energy.A continuous noise may not reach the threshold of 90 dB(A). An interrupted noise has to be evaluated by means of the equivalent noise level L_eq and may not reach the value L_eq of 90 dB(A). The risk of deafness caused by excessive noise can be evaluated by means of L_eq and the duration of exposure in years. If a situation reaches or surpasses the limit, protection measures have to be taken. With the help of technical measures, noise can be reduced at the source as well as in its spreading. Organisational measures can shorten the duration of exposure. Finally, individual hearing protection apparatuses offer a preventive measure, but in no case can they replace the other means of protection.

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La surdité dans l'industrie

Résumé Des essais sur le déplacement temporaire du seuil auditif servent de modèle pour l'étude de la surdité permanente. Le déplacement temporaire du seuil auditif causé par des sons de haute intensité (plus de 90 dB) est de plusieurs fois plus marqué que celui causé par des intensités faibles. Ce déplacement est proportionnel à la durée de l'exposition. Son décroissement dure dix fois de plus que le son qui a provoqué le déplacement.Le déplacement temporaire du seuil auditif à la suite de périodes alternées de bruit et de calme ne comporte que la moitié du déplacement causé par un bruit continu de même énergie acoustique.Un bruit continu ne doit pas atteindre le seuil de 90 dB(A). Un bruit discontinu est à évaluer au moyen du niveau sonore équivalent permanent L_eq et ne doit pas atteindre la valeur L_eq de 90 dB(A). Le risque de surdité par un bruit excessif peut être évalué au moyen du L_eq et de la durée de l'exposition en années. Lorsque une situation de bruit atteint le seuil limite, il faut appliquer des mesures de protection. Le bruit peut être atténué à la source et lors de sa propagation avec des moyens techniques. Des mesures organisatrices sont capables de réduire la durée de l'exposition. Enfin, les appareils individuels protègent également contre le bruit, mais ils ne doivent en aucun cas remplacer les autres mesures de protection.

     

High-frequency audiometry in the evaluation of critical noise intensity

Summary We investigated a total of 537 subjects (68 men, 469 women) working in the textile industry to ascertain their hearing level in the conventional hearing range as well as in the high-frequency (HF) range. The persons we tested work at three different noise-levels [80–84, 85–89, 90–94dB (A), measured as l_eq). The differences in the hearing thresholds between this three groups mentioned were checked by means of discriminant analysis. The first hearing level changes at a noise-level below 90 dB (A) l_eq develop mainly in the HF range. In the conventional hearing range, however, the hearing levels remain unchanged even over long exposure times. Noise-induced hearing loss in the conventional range occurs only in the sound level group of 90 to 94 dB (A) l_eq without attaining any social importance. The tests show that, if the noise-level 90 dB (A) leq is not exceeded, no noise-induced hearing impairments involving social hearing loss are to be observed. Thus we assume that an auditory risk criterion of 85 dB (A) l_eq is sufficient to prevent hearing loss of any social importance.     

Traffic noise and other determinants of blood pressure in adolescence

BackgroundExposure to traffic noise has been associated with hypertension in adults but the evidence in adolescents is limited. We investigated long-term road traffic noise exposure, maternal occupational noise during pregnancy and other factors in relation to blood pressure and prehypertension at 16 years of age.MethodsSystolic and diastolic blood pressure were measured in 2597 adolescents from the Swedish BAMSE birth cohort. Levels of road traffic noise were estimated at home addresses during lifetime and for the mother during pregnancy as well as maternal occupational noise exposure during pregnancy. Exposure to NO_x from local sources was also assessed. Associations between noise or NO_x exposure and blood pressure or prehypertension were analysed using linear and logistic regression.ResultsThe prevalence of prehypertension was higher among males and in those with overweight, low physical activity or overweight mothers. No strong or consistent associations were observed between pre- or postnatal exposure to road traffic noise and blood pressure at 16 years of age. However, inverse associations were suggested for systolic or diastolic blood pressure and prehypertension, which reached statistical significance among males (OR 0.80 per 10 dB L_den, 95% CI 0.65–0.99) and those with maternal occupational noise exposure ≥ 70 dB L_Aeq8h (OR 0.60, 95% CI 0.41–0.87). On the other hand, occupational noise exposure during pregnancy tended to increase systolic blood pressure and prehypertension risk in adolescence. No associations were seen for NO_x exposure.ConclusionNo conclusive associations were observed between pre- or postnatal noise exposure and blood pressure or prehypertension in adolescents.     

地铁站勤务人员个体噪声暴露的监测与分析

目的 采用个体噪声暴露测量方法,了解地铁站勤务人员噪声暴露的水平和特点,为地铁站勤务人员的噪声职业危害控制提供依据。方法 以城市地铁某线路6个站点的4类岗位勤务人员为对象,用记录式噪声个体计量仪对地铁运行时间段内各岗位勤务人员进行个体噪声暴露测量。结果 城市地铁站的现场复杂,噪声源数量多、不稳定。在受检的48名勤务人员中,车站机房岗位的工作班内加权平均等效A声级（LAeq）水平最高为（81．8±2．5）dB（A）,车站控制岗位班内加权平均LAeq最低为（68．7±1．8）dB（A）;车站厅巡岗位班内加权平均LAeq水平极差最大为8．1dB（A）,车站控制岗位班内加权平均IAeq水平极差最小为4．0dB（A）。结论 地铁站勤务人员个体噪声暴露极不均一,用个体噪声暴露测量方法能较灵敏、完整地反映地铁站勤务人员的复杂噪声暴露状况。     

Instantaneous changes in sleep stage due to the sound of a passing truck]

The instantaneous effect of the sound of a passing truck on sleep of five male students, 23 to 25 years of age, was assessed. The peak levels of noise were adjusted to 55, 60, and 65 dB (A) with intervals of 18 and 13 minutes, and a frequency of one per hour. Background noise in the experimental room was Leq 42 dB (A). The sleep stage of each epoch was visually judged based on the criteria of Rechtschaffen & Kales. Data for pre-exposure epochs of sleep stage 2 and rapid eye movement (REM) were collected and 18 epochs, including two under noise exposure, were evaluated. Three sets of polygraphic data were sampled as controls from 10 minutes after 65 dB (A) exposure to the next exposure. Compared with the control, the percentage of stage 2 to shallower stages (stage 1, waking, or movement time (MT)) was significantly increased by exposure to 55, 60, and 65 dB (A). The change lasted for one minute with exposure to 55 dB (A), and 2 to 3 minutes with 60 and 65 dB (A). A decrease in the percentage of stage 2 to deeper stages was observed at 2 to 4 minutes after exposure to 60 and 65 dB (A). The percentage of stage 2 to MT increased at 60 and 65 dB (A). The percentage of stage REM to other stages increased with the exposure to 60 or 65 dB (A) within 4 minutes. The threshold of instantaneous change of stage 2 to shallower stages due to the sound of a passing truck was at the peak level at less than 55 dB (A), and that of stage REM to other stages at 55 to 60 dB (A).     

冷轧厂工人个体噪声暴露测量的初步分析

目的采用个体噪声暴露测量方法,了解冷轧厂工人噪声暴露的水平和特点,为防治轧钢工的噪声职业危害提供基础数据。方法以轧钢厂4个主要工艺中的11个工种为分组单位,每组抽取3～5人,用SH-126记录式个体声剂量计对白班（8：00至16：00）工人进行个体噪声暴露测量,同时填写工时记录,计算8h等效A声级。结果轧钢厂现场复杂,噪声源数量多、不稳定,工人同时受到多个噪声源的影响,个体噪声暴露声压级波动大。53名工人中个体噪声暴露最大值为100．0dB（A）。最小值为81．2dB（A）;噪声暴露水平最高的头部焊工为94．20dB（A）,最低的纵切剪切工为89．02dB（A）;质量枪验工组内极差最大,为16．3dB（A）;轧机主操作上极差最小,为2．3dB（A）。提示采取个体噪声暴露测量方法能比较准确、完整地反映冷轧厂作业工人的复杂噪声暴露情况。结论冷轧厂个体噪声暴露均超过85dB（A）,应加强噪声防护。个体噪声剂量计是以工人为主体,反映个体的噪声暴露情况和接触水平。     

Acute and chronic endocrine effects of noise: Review of the research conducted at the Institute for Water,Soil and Air Hygiene

This is a review of the research into endocrine effects of noise since the early 1980s at the Institute for Water, Soil and Air Hygiene. According to our knowledge, no other group has studied systematically the endocrine effects of acute and chronic noise exposure. Mechanisms of acute noise-induced stress reactions as well as long-term increase of stress hormones in animal and persons under chronic noise exposure were studied. Our theoretical background was Henry's psychophysiological stress model with the two reaction alternatives : (i) The fight-flight reaction, characterised by an increase in adrenalin and noradrenaline (ii) The defeat reaction with increased cortisol. Extremely intense acute noise exposure near the threshold of pain caused an increased release of cortisol from the suprarenal cortex but acute noise exposure with levels between 90 and 100 dB(A) caused an increase of catecholamines. Non-habituated noise increased primarily the release of adrenalin from the suprarenal medulla, whereas habituated noise caused a chronic increase of noradrenaline from the sympathetic synapses under longterm noise exposure at work. Environmental noise exposure (Leq >/= 60 dB(A)) caused catecholamine increase if activities such as conversation, concentration, recreation etc were disturbed through noise. In sleeping persons, traffic noise with only Leq >/= 30 dB (A) and Lmax >/= 55 dB(A) caused significant acute increase of cortisol, which developed into chronic increase if the noise exposure was repeated consistently. Parallel to cortisol, chronic noradrenaline increase was also observed. Based upon the empirical results, a noise stress model was developed which is a first step forward in the theoretical understanding of endocrine noise effects.     

学校噪声的污染现状及其行为毒理学研究

本文从环境卫生学和行为毒理学的角度，研究了学校噪声的来源、污染现状及其对实验动物和中小学师生行为的影响。结果表明，学校噪声污染严重，等效声级平均为６２ｄＢ（Ａ），超过６５ｄＢ（Ａ）的学校占被调查学校的３３．３％。噪声主要来源于交通噪声。根据行为毒理研究结果，提出学校室外１ｍ噪声标准的建议值（Ｌｅｇ）为５５ｄＢ（Ａ）。本研究为制订学校噪声标准和噪声防治提供了科学依据。