Effects of Aircraft Noise: Research Update on Select Topics (2008)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Trying to identify, measure, and quantify any potential effects of aviation noise on health is a complex and difficult field of study. Variations on how to identify and/or measure the noise exposure itself (single dose, long-term average, number of events above a certain level, etc.), and attempting to separate the effects from other life events are difficult at best. For example, lifestyles, life’s stressors, hereditary factors, and genetic composition are just a few factors that may distort potential results of an aviation noise health effects study. Given this complexity, the large amount of research pub- lished during the past 30 years has produced considerable variability of results; often, some are quite controversial. The absence of one internationally acceptable “exposure-effect” or “dose-response” relationship is largely the result of the lack of one obvious “best choice” research methodology. After reviewing all new research, reviewing previous research with new thought, and collaborative efforts to identify health effects related solely to aviation noise were completed, four main subject areas were identified: cardiovascular effects, aviation noise effects and children, aviation noise effects on hospitals and care facilities, and potential hearing impairment. Each is discussed separately here. CARDIOVASCULAR EFFECTS Several recent studies have reviewed previous literature, either through compilation or re-review of original data, which suggest that increased hypertension or other cardiovas- cular effects may be associated with particular long-term noise exposure. For example, in 2000 at a World Health Organization expert task force meeting, a weak association between long-term environmental noise exposure and hyper- tension was suggested, but no dose-response relationship could be established (Guidelines for Community Noise 2000). It concluded that cardiovascular effects may be associated with long-term exposure; however, the associations are weak and the effect is somewhat stronger for ischemic heart dis- ease than for hypertension. Another example, a study by Passchier-Vermeer and Passchier (2000) reviewed existing literature that stated there was sufficient scientific evidence that noise exposure can induce hearing impairment, hyper- tension, and ischemic heart disease. It concluded there were no obvious effects from noise exposure on mean diastolic and 8 mean systolic blood pressure; however, some effects were observed in terms of an increase in the percentage of individ- uals with hypertension. Most reviewers concluded that previous reviews were not carried out in a systematic way, which makes them prone to bias. Reviewers pointed out the tendency for some studies to inadequately report noise exposure data. In 2002, for example, Van Kempen et al. concluded that whereas “noise exposure can contribute to the prevalence of cardiovascular disease, the evidence for a relation between noise exposure and ischemic heart disease is still inconclusive, because of the limitations of exposure characterization, adjustment for important con- founders, and occurrence of publication bias.” No differences in systolic and diastolic blood pressure have been found in cross-sectional studies comparing areas near an airport with calm, suburban areas; therefore, aircraft noise lev- els were not a factor in these two subject areas. One should note that cross-sectional studies are notoriously difficult to interpret. They often report conflicting results, generally do not identify a cause and effect relationship, and often do not report a dose-response relationship between the cause and effect. AVIATION NOISE EFFECTS AND CHILDREN Another particular concern over the last 30 years is the potential health effect on children owing to exposure to or interference from aviation noise. Published studies include the effects of aircraft noise and mental disturbances by means of a cross-sectional study in two contrasting geo- graphical regions. Although noise levels were not reported, they are likely to be very high, as military aircraft fly as low as 75 m with very high onset rates. Neither psychiatric disorders nor environmental factors showed any relation- ship to noise; however, psychophysiological parameters (e.g., heart rate and muscle tension) did demonstrate some relationship to noise. Other recent studies have focused on relationships between noise exposure during pregnancy and low birth weights; however, no association was found between personal noise exposure (measured in decibels) and birth weight (Wu et al. 1996; Passchier-Vermeer and Passchier 2000). Other possible noises (e.g., occupational, traffic noise, and history of listening to amplified music) also showed no effect on infant birth CHAPTER TWO HEALTH EFFECTS OF AVIATION NOISE

considerable research, review of previous research with new thought, and new independent research, as well as collabora- tive efforts to identify health effects related to aviation noise have been completed. Some studies have identified a poten- tial correlation between increased hypertension and aviation or road noise above certain noise thresholds; however, other studies contradict such findings. Occupational noise often becomes an intricate concern. Health effects on children, particularly those with decreased cognitive abilities, mental disturbances, or other psychological stressors, and studies of pregnancy and low infant-birth weights, all indicate there is no correlation between aviation noise and childhood psychi- atric disorders, environmental factors, or low infant-birth weights. Additionally, recent studies conclude aviation noise does not pose a risk factor for child or adolescent hearing loss, but perhaps other noise sources (personal music devices, concerts, motorcycles, or night clubs) are a main risk factor. Because aviation and typical community noise levels near airports are not comparable to the occupational or recreational noise exposures associated with hearing loss, hearing impairment resulting from community aviation noise has not been identified. Although newer studies suggest there may be a potential relationship between aviation noise levels and hypertension or ischemic heart disease at noise levels as low as 50 dBA Leq (equivalent sound level), further research is necessary. One such study only found that effect for night aircraft noise (Eriksson et al. 2007). Among the confounding factors in studies of hypertension and aircraft noise is that aircraft noise exposure is taken from noise model estimates without regard to ambient noise levels. The ambient noise levels in urban areas and most suburban areas exceed 50 dBA Leq. Further, only a handful of recent studies attempted to segregate health effects of noise from that of air pollution near airports. Despite decades of research, including review of old data and new research efforts, health effects of aviation noise continue to be an enigma. Most, if not all, current research concludes that it is as yet impossible to determine causal relations between health disorders and noise exposure, despite well-founded hypotheses. weights. The reader is also referred to chapter six, “Effects of Aviation Noise on Schools” for additional information. HOSPITALS AND CARE FACILITIES A careful search for research regarding aviation noise and hospitals and care facilities did not identify any studies that address this particular issue. Most airport noise and land-use compatibility guidelines list hospitals and care facilities as noise-sensitive uses, although there are no studies that have identified health effects associated with aviation noise. How- ever, there are numerous studies that identify problems with internal hospital noises. HEARING IMPAIRMENT Although aviation noise exposure and potential hearing impairment during all ages of life are common research areas, the research is much more definitive, usually owing to adequate controls, data, and identifiable conclusions. For example, in 1999, a study by Ludlow and Sixsmith reviewed nine studies undertaken in the vicinity of seven civil and military airports, and two laboratory studies, finding that “the laboratory studies suggest that permanent threshold shifts are unlikely to be induced by exposures to aircraft noise thought to be typical of real life.” The reviewed studies concluded “environmental noise does not appear to approach recog- nized occupational noise limits. Furthermore, it may be that the intermittency of environmental noise itself may protect hearing from damage” (Ludlow and Sixsmith 1999). These conclusions are echoed in several other studies as well, because environmental noise does not approximate occupa- tional noise levels or recreational noise exposures (e.g., personal listening devices, concerts, or motorcycles), as it does not have an effect on hearing threshold levels. Lastly, studies have also shown that early noise exposure as a child on military jet aircraft bases does not make one more sus- ceptible to noise-induced hearing loss. In conclusion, in the more than 23 years since publication of Aviation Noise Effects (Newman and Beattie 1985) 9