Health effects caused by noise: evidence in the literature from the past 25 years.

Traffic noise is the most important source of environmental annoyance. According to the Environmental Expert Council of Germany, severe annoyance persistent over prolonged periods of time is to be regarded as causing distress. Previously, extraaural noise effects were mostly assessed using a paradigm in which the sound level played the major role. On the basis of this paradigm the relatively low sound level of environmental noise was not considered to be a potential danger to health. In contrast to this numerous empirical results have shown long-term noise-induced health risks. Therefore a radical change of attitude - a change of paradigm - is necessary. For an immediate triggering of protective reactions (fight/flight or defeat reactions) the information conveyed by noise is very often more relevant than the sound level. It was shown recently that the first and fastest signal detection is mediated by a subcortical area - the amygdala. For this reason even during sleep the noise from aeroplanes or heavy goods vehicles may be categorised as danger signals and induce the release of stress hormones. In accordance with the noise stress hypothesis chronic stress hormone dysregulations as well as increases of established endogenous risk factors of ischaemic heart diseases have been observed under long-term environmental noise exposure. Therefore, an increased risk of myocardial infarction is to be expected. The results of individual studies on this subject in most cases do not reach statistical significance. However, according to the Environmental Expert Council, these studies show a consistent trend towards an increased cardiovascular risk if the daytime immission level exceeds 65 dB(A). Most of the previous studies on the extraaural effects of occupational noise have been invalidated by exposure misclassifications. In future studies on health effects of noise a correct exposure assessment is one of the most important preconditions.

Analysis and modeling of the treatment process characterizing the cooperation within multi-professional treatment teams.

We would like to introduce several aspects of the analysis and modeling of the treatment process characterizing the cooperation within multi-professional treatment teams. We will determine what is meant by a treatment process in order to then look at five views and four levels of their description. We will introduce possible methods for surveying and describing it. Currently an extensive analysis of the current state of the treatment process and of the weaknesses is underway in the Department of Child and Adolescent Psychiatry of the Heidelberg University Medical Center.

Subjective work noise: a major risk factor in myocardial infarction.

The relationship between subjective work noise exposure and the risk of myocardial infarction (MI) was assessed in a population based case-control study. 395 MI patients (31-65 years) were compared to 2148 controls from a random population sample with the same agelsex distribution. The relative risk (RR) for MI-adjusted for control variables (smoking, age, social status, etc.)-was found to increase significantly and steadily with noise category. Subjective work noise exposure was the second greatest risk factor for MI after smoking. Possible bias due to overreporting of subjective noise exposure is discussed. Interdisciplinary studies on the relationship between cardiovascular diseases and work-related stressors including subjective and objective noise assessment are needed to quantify the risk of MI due to work noise.

[Empirical studies of music listening habits of adolescents. Optimizing sound threshold limits for cassette players and discoteques]. / Empirische Untersuchungen zu Musikhörgewohnheiten von Jugendlichen. Optimierung der Schallpegelbegrenzung für Kassettenabspielgeräte und Diskotheken.

The music habits of 569 pre-teens and teenagers, between 10 and 17 years of age, were examined and exposure to music from portable music players was compared to that in discotheques. Using a questionnaire we determined the length of time spent listening to portable music players and the frequency of disco visits. The individual level of the music heard through portable music players was measured as a free-field corrected short term mean level. The total music exposure (related to 40 hours per week) was calculated from the data and different assumed disco sound levels. We estimated the risk of ear damage according to ISO 1999 standards on the basis of the total music exposure, whereby the mean disco level was varied as a parameter in the range of 95 to 110 dB(A). Taking only the portable music players into account, one can expect that even after 5 years of music, approximately 5% of the total group would have a hearing loss of 20 dB. This percentage clearly rises when additional exposure is given in discotheques having music levels above 100 dB(A). We suggest therefore that for safety reasons the following sound levels should be observed: 90 dB(A) for portable music players and 95 dB(A) for discos. Through adherence to these levels we would expect that 1% of the young people in our study would have a hearing loss > 10 dB, whereas momentary exposure would result in a hearing loss > 10 dB of 10-20%. Therefore we believe that sound level limitations should be enacted immediately for portable music players and in discotheques.

[Sensorineural hearing loss in children starting school. Results of a representative hearing screening study]. / Sensorineurale Gehörschäden bei Schulanfängern. Ergebnisse einer repräsentativen Hörscreeninguntersuchung.

Audiograms in the 0.5-6 kHz frequency range were taken, using improved audiometric screening methods, in 2032 children, 6-7 years old, who were undergoing their pre-school medical examinations. In 151 children (7.4%), the threshold for hearing was above 20 dB for at least one frequency. Of these, 82 children (4% of the overall sample) had a hearing impairment defined as a difference of > or = 10 dB between at least one frequency (3, 4 or 6 kHz) and the mean value from 1+2 kHz. This was evaluated as a sensorineural hearing loss. Unilateral losses (lateral difference > or = 10 dB) were more common than bilateral losses (2.5% vs 1.6% of the overall sample). These unilateral hearing losses in the high-frequency range are essentially regarded as the result of playing with impulse-noise producing toys, such as toy guns with caps.

[The effect of the ventilation rate on the air particle and air microbe concentration in operating rooms with conventional ventilation. 2. Measurement during surgical activity with respect to surgical personnel number and surgical activity phases]. / Der Einfluss der Luftwechselzahl auf Luftpartikel- und Luftkeimkonzentrationen in Operations-Rümen mit knoventioneller Belüftung. 2. Mitteilung: Messungen mit Operations-Betrieb unter Einbeziehung der OP-Personenzahl und OP-Betriebsphasen.

For measurements with surgical activity, it was investigated if the air-exchange-rate has a significant influence on airborne particle and bacteria concentrations in two conventionally ventilated operating theatres. Next to that the influence of number of personnel in the operating theatre and the various operating phases were calculated (explanation of variance). Statistical differences were found for airborne particle concentrations and a few for airborne bacteria concentrations in supply and ambient air. From the hygienic point of view these differences must be considered to be irrelevant because of the little margin (less than one lg-step) between the values. The comparison of all air-exchange-rates as well as that between the two air-exchange-rates in the two operating theatres show that the number of personnel present in the operating theatre has the most influence on airborne particle concentrations variance. Concerning airborne bacteria concentrations explanation of variance by the treatment factors air-exchange-rate, personnel and operating phase is negligible. Summarizing the low (7.5 and 10/h) and high (15 and 20/h) air-exchange-rates did not increase the explanation of variance for airborne particle and bacteria concentrations although the differences were on a significant level.

[The effect of the ventilation rate on air particle and air microbe concentration in operating rooms with conventional ventilation. 1. Measurement without surgical activity]. / Der Einfluss der Luftwechselzahl auf Luftpartikel- und Luftkeimkonzentrationen in Operations-Räumen mit konventioneller Belüftung. 1. Mitteilung: Messungen ohne Operations-Betrieb.

The question was if a reduction of airborne particles and bacteria in conventionally (turbulently), ventilated operating theatres in comparison to Laminar-Airflow (LAF) operating theatres does occur at high air-exchange-rates. Within the framework of energy consumption measures the influence of air-exchange-rates on airborne particle and bacteria concentrations was determined in two identical operating theatres with conventional ventilation (wall diffusor panel) at the air-exchange-rates 7.5, 10, 15 and 20/h without surgical activity. This was established by means of the statistical procedure of analysis of variance. Especially for the comparison of the air-exchange-rates 7.5 and 15/h statistical differences were found for airborne particle concentrations in supply and ambient air. Concerning airborne bacteria concentrations no differences were found among the various air-exchange-rates. Explanation of variance is quite high for non-viable particles (supply air: 37%, ambient air: 81%) but negligible for viable particles (bacteria) with values below 15%.

Traffic noise as a risk factor for myocardial infarction.

The hypothesis that road traffic noise causes ischaemic heart disease (IHD) was tested in several epidemiological studies in middle-aged men. The studies carried out in Caerphilly (Wales) and Bristol-Speedwell (England) suggested the daytime (6-22 h) outdoor traffic noise level category 65-70 dB(A) as a threshold for noise effects detectable. Based on risk factors, a relative risk greater than 1 was calculated for the incidence of major IHD (RR = 1.1) in both samples for the subjects in this highest noise category, those in the quietest (51-56 dB(A)) serving as a reference using multiple models. Also the prevalence of myocardial infarction (RR = 1.2 and 1.1), ECG ischaemia (RR = 1.2 and 1.4) and any IHD disease (RR = 1.2 and 1.2) showed relative risks slightly greater than 1 in this noise group. In contradiction, the observed incidence of major IHD showed relative risks below 1 in both samples in this traffic noise group. The case-control studies carried out in Berlin revealed relative risks above 1 on the incidence (RR = 1.3 and 1.2) and the prevalence (RR = 1.2) of myocardial infarction at outdoor traffic noise levels in the range of 71-80 dB(A) serving the men in the category below 61 dB(A) as a reference. None of the findings was statistically significant. The relevance of the results is discussed.

[Evaluation of technical indoor air ventilation systems in operating departments from the health viewpoint]. / Uberprüfung von Raumlufttechnischen (RLT-) Analgen in Operationsabteilungen unter hygienischen Gesichtspunkten.

By means of measurement examples it is shown that the examination of the cfu-concentration in the supply-air is not a sufficient criterion for the hygienic-microbiological evaluation of air-conditioning systems in operation wards. Maximum upper values for cfu-concentration were only exceeded a little in some cases. Particle measurements, carried out simultaneously, gave further information on the hygienic status of the air supplied by the air-conditioning system and permitted an evaluation of the ventilation system (for example an air-supply ceiling with a stabilized air ventilation). An efficient air-ventilation system should have the effect that the air quality in the operation area is of nearly the same quality as the supply-air. On the basis of own measurements maximum upper values and recommended values for cfu- and in particular particle-concentrations in the supply-air of air-conditioning systems with three-step filtration were proposed. The set-up and the carrying out of the measurement is described to standardize a "hygienic evaluation" of air-conditioning systems in operation theatres. Help for the interpretation of measurement results is given by means of measurement examples.