Evaluation criteria for aircraft noise

Based on extensive and detailed reviews the present paper suggests evaluation limits for aircraft noise for the prediction of noise effects and for the protection of residents living in the vicinity of (newly constructed or extended) civil airports. The protection concept provides graded assessment values: Critical Limits indicate noise loads that shall be tolerated only exceptionally during a limited time. Protection Guides are central assessment values for taking actions to reduce noise imission. Threshold values inform about measurable physiological and psychological reactions due to noise exposures where long term adverse health effects are not expected. Evaluation limits are provided for various protection goals. Apart from hearing damage, evaluation limits are provided for the avoidance of primary extraaural effects on communication and on sleep, for the avoidance of annoyance as a secondary effect and for the avoidance of suspected cardiovascular diseases. Such limits enable authorities to outline the areas around airports, where appropriate measures are mandatory to protect residents against the deleterious effects of noise. Protecting residents is a dynamic process that must be followed up. The evaluation limits must be repeatedly tested in view of new scientific findings and adapted, if necessary.     

Impulse noise and risk criteria

Impulse noise causes evidently more severe hearing loss than steady state noise. The additional effect of occupational impulse noise on hearing has been shown to be from 5 to 12 dB at 4 kHz audiometric frequency. Reported cases for compensated for hearing loss are prevalent in occupations where noise is impulsive. For impulse noise two measurement methods have been proposed: the peak level method and energy evaluation method. The applicability of the peak level method is difficult as even the recurrent impulses have different time and frequency characteristics. Various national risk criteria differ from international risk criteria. In France the maximum A-weighted peak level is 135 dB, and in the United Kingdom the C-weighted peak sound pressure is limited to 200 Pa (140 dB). This criterion of unweighted 200 Pa (140 dB) is used in European Union (EU) directive 86/188 and ISO 1999-1990 regardless of the number of impulses. The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that no exposure in excess of a C-weighted peak sound pressure level of 140 dB should be permitted. At work places these norms do not cause any practical consequences since the impulses seldom exceed 140 dB peak level. In several occupations the impulses are so rapid that they contribute only a minimal amount to the energy content of noise. These impulses can damage the inner ear even though they cause reduced awareness of the hazard of noise. Based to the present knowledge it is evident that there is the inadequacy of the equal energy principle in modelling the risk for hearing loss. The hearing protectors attenuate industrial impulse noise effectively due to the high frequency contents of impulses. Directive regarding the exposure of workers to the risks arising from noise requires that in risk assessment attention should be paid also to impulsive noise. So far there is no valid method to combine steady state and impulse noise. A statistical method for the measurements of industrial impulse noise is needed to get a preferably single number for risk assessment. There is an urgent task to develop risk assessment method and risk criteria for impulsive noise to meet the requirements of the upcoming European Union noise directive.     

Community noise: health effects and management.

This commentary will reemphasize the importance of urban noise as a health problem and provide a practical approach toward implementing legislative controls. References and a short discussion of accepted ways to measure noise are included. Furthermore, a brief review of relationships between noise and the development of disease is discussed. Finally, a six-part noise control ordinance framework designed to help public health and community leaders start the process of urban and community noise reduction is detailed. The implementation of such enforceable and reasonable noise control ordinances will be good public health policy and will greatly impact the quality, and possibly quantity, of life of both the individual and the community.     

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.     

Community noise policy in Denmark

This paper summarizes an analysis of Danish policy on community noise during the last three decades seen in a public health perspective. Estimates made during this period of population exposures to noise from transport are presented, followed by data on population reactions to community noise. The analysis of the main elements of Danish community noise policy in the form of remedies, preventive actions and strategies leads to the conclusion that although exposures of the population to community noise have decreased during this period, the Danish policy was not consistent in the 1970s and 1980s. Administratively and politically, noise had low priority as an environment problem. The improvements in exposures from road traffic were probably mainly due to the legislation on physical planning, but also to lower speed limits and local traffic planning measures. During recent years important new steps have been taken, including the railway sector, but air traffic noise still represents a problem. Local authorities have, generally, been slow in giving priority to noise alleviating and preventive actions. Improved coordination at the central level is needed, and local action may raise the general awareness of the importance of our noise environment for health and well-being.     

District classification according to noise prevention criteria

The legalities of the GDR being valid for the protection against noise demand an obligatory classification of the municipal areas with different limits. These limits are comprised compulsory in the GDR-Standard TGL39617 - Protection against Noise; Limits of Noise Immission in Communal Reach. The organs of state and economy have to guarantee observing these limits. The classification of the municipal areas is difficult, because the architects plan the general land use with respect economic points of view, contrary to the organs of hygiene witch have regard to the localisation of the noise sources. The authors propose possibilities to the introduction of steps of save load against noise and to further subdividing of the structure from noise limits.     

V. Medical effects of aircraft noise: Community cardiovascular survey

Summary Data of a community cardiovascular survey in the area around Schiphol airport (Amsterdam) were related to existing aircraft noise levels.About 6,000 people (men and women, aged 35–64 years) were screened. Afterwards the participants were divided into two groups: those living in areas with more (NNI > 37) and those living in areas with less (NNI = 20–37) aircraft noise.It appeared that in areas with more aircraft noise, more people were under medical treatment for heart trouble and hypertension and — especially more women — took cardiovascular drugs. Moreover, in areas with more aircraft noise in more people high blood pressure and pathological heart shape were observed. The discrepancies that were found could not be explained by age, sex, smoking habits, height/weight, and — as far as this could be checked — by socio-economic differences. In areas with more aircraft noise roughly 50% more people had cardiovascular impairment.     

Community noise annoyance risk in two surveys

Two noise annoyance surveys were performed in Bratislava, the capital of the Slovak Republic, in a ten-year interval (1989-1999). This was a period of political and socioeconomic transformation as well as of changes in traffic management. Equivalent noise levels were assessed at the dormitory (exposed group) and in the residential areas (100 measuring stations) where another group of students (control group) lived. The mean dormitory and the mean control area equivalent noise levels increased significantly after ten years. In comparing current and previous risks of different noise exposures, the current risk was much higher for the group exposed to road traffic noise annoyance (OR = 6.01; 95% CI: 4.97-7.95 vs OR = 2.56; 95% CI: 1.93-3.42), entertainment facilities and neighborhood noise annoyance. Current road traffic noise interference with various activities (reading and mental work, personal communication, telephone communication, sleep) was also higher than previously. The students of the exposed group considered their health status in 1999 worse than ten years earlier (OR = 1.35; 95% CI: 0.99-1.83 vs OR = 0.82; 95% CI7 0.55-1.22) and they were generally taking more drugs. The comparison of two noise annoyance surveys showed that the load of community noise, especially road traffic noise as well as the subjective response to the noise, had increased in Bratislava.     

Assessment of occupational noise exposure: methodology, measurement error, evaluation criteria

BACKGROUND: Occupational noise exposure can be monitored directly by personal sampling or indirectly, by area sampling. Personal sampling is performed using an integrating sound level meter, worn by the worker while performing his/her job. When area sampling is used, measurements need to be made in all locations where a typical worker stays while performing his/her tasks; the respective partial lengths of exposure need to be accurately monitored, and the time-weighted average sound level of the measured noise levels must be calculated. OBJECTIVES: Current regulations identify three different thresholds, corresponding to different types of action, but they do not propose any standard criteria to decide whether a threshold has been exceeded. Defining standard procedures to assess occupational noise exposure and identifying such thresholds is crucial. METHODS: Using empirical data collected in the field, the effects are illustrated of the number of sampling locations and of the partial lengths of exposure on area sampling measurements, and the effects of duration of noise exposure on both area and personal samplings. RESULTS: When dealing with area samplings, an accurate definition of both sampling locations and partial lengths of exposure is crucial. When arbitrary decisions are taken in selecting sampling locations and/or establishing partial lengths of exposure, spatial changes in noise level and operator' displacements while performing his/her tasks may affect results. Sampling for less than the duration of noise exposure is the major contributor to measurement error, particularly under conditions of unpredictable variation in noise level. In fact, as noise level in the non-monitored time fraction is unknown, measurement error cannot be determined. We estimate that, even under the most favorable circumstances, sampling should last not less than 40% of the duration of a given noise-generating occurrence, for repeated measurements to be dispersed within a range not wider than that generated by the instrumental error. Inter-daily variability is another important aspect in personal noise exposure evaluation. This is a general occurrence, whose effects cannot be controlled by simply considering weekly instead of daily exposures. Results of an investigation, covering about 60 different jobs within a primary aluminum plant, show an inter-daily variability in noise exposure greater than 5 dBA in about 75% of cases. CONCLUSIONS: Personal sampling, when correctly performed and covering the total duration of exposure, provides the most reliable result as it integrates noise over all locations where the worker actually stays while performing his/her tasks, and over the total length of time spent in each task. We propose extending personal sampling to the total duration of actual noise exposure as the standard procedure for monitoring daily personal noise exposure, and valid for the majority of work places. When the range of daily noise exposure includes one regulatory threshold, corresponding to a given type of action, we propose as a standard decision criterion to refer prudentially to the upper 95% confidence limit of the LEP,d arithmetic mean. Such criterion would allow to standardize procedures and decision methods, with the prospect of further improvements in the assessment of exposure to noise.     

Interpreting noise dosimeter results based on different noise standards.

Three types of noise dosimeters were exposed on workers during routine work in a synthetic rubber plant, two refineries, a petrochemical plant, a petroleum marketing terminal and an off-shore producing platform. The dosimeters represent different methods of noise integration.     

Aircraft noise annoyance and average versus maximum noise levels.

A questionnaire study was performed in seven areas located around the airports of Landvetter and Save, Gothenburg, in an attempt to elucidate the extent of annoyance in populations exposed to aircraft noise. Noise exposure was estimated as the energy equivalent level (Aircraft Noise Level--FBN) or as the number of aircraft with levels that exceeded 70 dBA, combined with the maximum noise level. The results were compared with data obtained from the earlier Scandinavian Aircraft Noise Investigation. The results supported the conclusion that the annoyance reaction is better related to the number of aircraft and the maximum noise level than to energy equivalent levels for noise exposure.