[An investigation of the environment in a certain vanadium refinery (author's transl)]

An investigation of the environment of the working place was made as part of the investigation of damages to health that had broken out in a certain vanadium refinery; and the following conclusions were obtained: When the atmospheric dust volume and V2O5 concentration by unit working step were measured with a high volume air sampler, V2O5 exceeded the threshold limit value given by ACGIH in the P.O. flake production step, while the measurement of V2O5 concentration during one-shift working hours with a low volume air sampler gave 64.3 micrograms/m3 even in the grinding step where the maximum concentration was found, and values under 10 micrograms/m3 in all the other steps. Such concentrations may be considered to have been derived from the fact that P.O. casting in accomplished in a short time, and that the fume and dust that are transiently produced at high concentrations are dispersed outdoors by spontaneous ventilation. Damages to health such as a high prevalence of green tongue appeared to have resulted from failure in exercising elementary sanitary care such as imperfect facilities for safety and sanitation, and failure to thoroughly enforce wearing of masks.

The effects of noise on telephone operators

1. One hundred twenty-nine telephone operators were given audiograms before work and again after four hours of work exposure. Since these operators habitually use the same ear for their monaural headset, the non-listening ear served as a yoked control in examining work related effects on hearing. The hearing threshold measurements conducted on the operators in this study disclosed no statistically significant shifts in mean threshold indicating no population effect for either short-term or long-term work exposure. 2. Two thousand random hours of magnetic tape recordings of operator positions disclosed the occurrence of 36 spurious signals of 94 dB SPL or above lasting from 0.4 to 145 seconds. The maximum amplitude recorded was 109 dB SPL. These tones occurred at a rate of about one per week per operator position. 3. On 36 operators reporting 51 incidents of acoustic disturbance, audiograms were obtained about 15 minutes and again at least 16 hours following the acoustic disturbance. No significant objective effects on hearing thresholds were identified.

Simplified occupational noise hazard prediction for new equipment

A simplified yet accurate method has been developed to predict noise hazards for new equipment by using only dB(A) noise levels, calculating power levels by the Two Surface Method and plotting a predicted noise isopleth. Noise levels can be accumulated for multiple sources. Room constants and other parameters can easily be varied to determine the most feasible and economical solution for noise problems.

Effect of firetruck noise on firefighters' hearing

Noise exposure of Minneapolis city firefighters was measured in 3 categories of fire apparatus. Maximum SPL of 110 db(A) and mean duration of 23 min/day do not exceed OSHA guidelines. The means pure-tone ac HTLs of a Group A of 17 men of 23-28 yrs with 0.75-2 yrs firefighting experience did not differ significantly from those of a comparable group of older men of 30-35 yrs with 8.25-10.9 yrs firefighting experience. Mean HTLs for both groups exceeded those of men of comparable age groups with no noise exposure tested by Corso, but at the lower frequencies only (0.5-4 kc/s), not at the higher (6-8 kc/s). Previous military and concurrent recreational noise exposure may have masked differences between Group A and B.

Method for determining complex operator noise exposures

This procedure describes a field method for determining operator noise exposures that cannot be assessed from single sound level meter readings. Noise exposures that should be evaluated by this method are those characterized by time-varying operator position sound levels--sound levels that change by three decibels or more while the meter is being read. The method is based on statistical concepts and requires multiple readings for a sample period whose length is prescribed by the desired precision of the results. This new procedure compares well with the theoretical accuracy of the best dosimeters. The actual performance of the new method has been shown to be better than the actual performance of the dosimeters.

High-speed drill noise and hearing: audiometric survey of 70 dentists

Many dentists believe that noise generated from high-speed drills results in a significant loss of hearing. Audiological evaluations, consisting of hearing thresholds at eight frequencies (500 to 800 Hz) and impedance audiometry, were done of 70 dentists from eight specialties. No statistical decrease in hearing thresholds appeared in either the speech or high frequencies when the dentists were compared with a normal, age-adjusted population.

Noise-induced hearing losses. Can they be explained by basilar membrane movement?

The development of noise-induced hearing losses must in some way be related to the basilar membrane movement. Our analysis of this relationship is based on Mössbauer effect measurements of the basilar membrane movement in human temporal bone preparations. At a single basilar membrane position in each of seven preparations, the displacement frequency response was measured for a given sound pressure level at the ear drum. The measurements covered the place range 2.2--6.2 kHz. Despite the inadequacy of the experimental data, there seems to be no doubt that low frequency components contribute substantially to the displacement and mechanical strain of the hair cells near the 4 kHz location, where the hair cells are known to be most vulnerable to noise damage. In fact, the analysis performed indicates that these cells will suffer the greatest mechanical strain, almost irrespective of the spectrum shape of the stimulus noise.

Comparison between stationary and personal noise dose measuring systems

In most of the investigations which have been made to survey occupational noise, a stationary sound level meter has been used either alone, or in combination with a stationary dosimeter. In this investigation, which was performed in a ship-building yard, an ear-borne noise dosimeter has been used. The Leq values which were obtained have been compared with those of the pocket-borne dosimeters. In many processes, considerable differences exist between pocket-borne and ear-borne dosimeters.

Noise-induced hearing loss in Danish brewery workers

An original computer-fitted diagnosis system for registration of noise-induced hearing loss (NIHL) is presented and compared with the tested persons' subjective hardness of hearing. Among 6 904 brewery workers it was found that people below 40 years only contract little NIHL during the first 5 years of noise exposure. The NIHL after more than 5 years of noise exposure is of the same magnitude as the hearing loss resulting from 10--20 years of age. The NIHL in older age groups was of a minor degree. Permanent use of hearing protectors was associated with good hearing, but the data suggest that good hearing might be the cause and not the effect of the use of hearing protection.

Work conditions and health of locomotive engineers. II. Questionnaire study, mortality and disability

A questionnaire study on work conditions, work organization, leisure time, social problems, and health was directed toward active and retired locomotive engineers. This article mainly presents responses of the active engineers. The active locomotive engineers quoted the irregular work hours as the worst occupational problem. They judged noise and vibration in the locomotive cabs as disturbing. The majority of the desired changes in the work and work conditions concerned work time. The most common complaints given on the questionnaire were back trouble, hypertension and dermatitis. Tiredness and exhaustion were the most prevalent neuropsychological symptoms. A retrospective follow-up survey on invalidity and mortality was made. Trainmen and railroad clerks were used as reference cohorts.The engineers had relatively high invalidity and mortality rates in comparison to the reference groups, especially with respect to cardiovascular diseases and malignant tumors. Higher rates for disease of the digestive system and hearing loss were also suggested by the results.

Comparison of the hearing threshold measured by pure-tone audiometry and by Békésy sweep audiometry

The hearing thresholds of 115 subjects, workers in a shipyard, were determined both by Békésy sweep audiometry and by conventional individual pure-tone audiometry at fixed audiometric frequencies. The Békésy method gave the lowest values for the hearing thresholds. It has been possible to find a useful linear relation between pure-tone and Békésy hearing thresholds. With the help of a retest experiment it has been established that the standard deviations of hearing thresholds, obtained under similar conditions in a pure-tone investigation, are about twice as large as those obtained in a Békésy investigation.

Noise and public health

Environmental noise has increased to the point that it affects large numbers of people. The most consistently demonstrated health effect of exposure to noise is hearing impairment. Other effects, such as stress reaction, irritability, fatigue and disturbances to physiologic function have been seen in laboratory research but are highly individualized and restricted to such specific populations as industrial workers. Rising background sound levels in communities due to increased traffic flow, industralization, work saving machinery, and other noise sources have caused community noise levels to become dangerously high. This factor is complicated by exposure to high sound level recreational activities with greater frequency and for longer periods. Recognizing the existence of the problem, governmental agencies have begun to identify the scope of the problem, to designate standards and regulations controlling noise sources, and to regulate allowable noise exposure for workers.

Hearing conservation: industrial aspects in California

Impaired hearing is a serious problem. The number of persons with a significant hearing loss has been estimated to be approximately 10 per cent of the population. Hearing loss owing to exposure to noise is becoming an increasingly important disease. Although it has been recognized for more than a century, little if anything was done to prevent it until a few years ago. The initiation of hearing conservation for employees has been undertaken by many of the large companies, particularly in California. Hearing conservation includes preemployment and follow-up hearing tests, control of noise at the source and personal protection (ear plugs, ear muffs).Noise-induced hearing loss is directly related to noise-exposure. Noise must be measured in terms of volume, wave length and length of exposure. Exposure must be analyzed for daily distribution and total time. Although the noise-exposure problem is a serious one, cooperation of employee, employer and the legal and medical professions to initiate preventive programs can reduce it to a minimum.