Health Based Criteria for Use in Managing Airport and Aircraft Noise
AbstractThis thesis questions whether an exposure-dose relationship between measurable aircraft sound and health can be established. The significance of this research is that highly concentrated global populations live near airports and are receiving a dangerous unknown and undefined health exposure. The question addressed is if aircraft sound originating from various heights has enough energy left upon reaching the ground to create measurable vibrations in human tissue. Simulated body tissue was isolated from the internal walls of a mock-up structure to make this determination. Vibration and sound data were collected near the Phoenix Arizona airport from over 60 aircraft as they passed overhead at heights varying up to two-miles above the ground.
The measurements demonstrated that the open air significantly attenuates most aircraft sound frequencies before they reach the ground. The experimental measurements were compared and contrasted to a non-health based sound criteria used by the Federal Aviation Authority (FAA) to determine variances against presently defined acceptable human impact. It was determined that most of the aircraft produced sound is not within the FAA criteria and that the portion that isn’t included causes harmful health effects. The frequencies that are the most significant component of aircraft sound energy are low frequency (200 Hz and less) and infrasound (20 Hz and less).
Experimentation demonstrated that aircraft produced infrasound and low frequency sound can travel almost a mile with minimal attenuation and are not blocked by common construction material. These sounds readily pass through and into common dwellings. Within the frequency range of about 5-40 Hz, similar amplitude/intensity infrasound and low frequency sound is being produced by each aircraft from approximately 4000 feet elevation and lower. This observation was generalized along the flight path of ascending aircraft from takeoff and allowed a description of a singular value of infrasound vibrational exposure beginning at the end of the runway to approximately five miles from the airport. Sound emanates out from either side of the aircraft and experimental data suggests a full exposure band of approximately one and a half miles wide. Partial reduced vibration exposures occur outside of the primary exposure band.
Low frequencies less than 40 Hz were measured in the experiment’s simulated human tissue and this exposure range poses health concerns. These vibrations match natural human body frequencies leading to human cell damage and the thickening of tissue (Alves-Pereira, 2007). A serious health issue caused by this vibration is increased cardiovascular risk, which has been identified near several airports throughout the world (Correia, 2013). This research strongly suggests that human tissue damage can occur from each flight event.
NextGen navigation is the future of aviation and its implementation poses a special additional health risk in that its application intentionally concentrates aircraft flight into tight corridors. This practice increases the number of exposures and conversely the health risk for those directly beneath the flight paths. When the flight path is over densely populated communities, a significant increased cardiovascular health risk for those exposed can be expected. This thesis did not determine a dose-thresh hold health relationship to over flights. This is an important suggested area for future research.
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