Towards understanding of inhalation exposure of pilots in the control cabin environment

Transport characteristics of TVOC in cockpits of commercial airliners have not been carefully studied relative to passenger cabins, and VOC emissions are currently not well regulated by the standards (e.g. ASHRAE, FAA, etc.). This study numerically performed a comprehensive assessment of cockpit environment using the developed all-in-one model, for the first time, integrating a full-scale A320 cockpit model and detailed manikins with 3D-rebuilt nasal cavity models. A generalised total volatile organic compound (TVOC) was selected as one representative gaseous contaminant and two representative emission scenarios in the cabin environment (aged and new aircraft) were analysed. Potential risky regions of the nasal system after inhaling the given contaminants were further evaluated. The outcomes demonstrated that windshield inlets were the key determinant of yielding the strong local vortex in the pilot's near field, which could potentially promote the contaminant lock-up. For aged aircraft, the average contaminant concentration in the pilots' breathing zone was nearly half of that in a brand-new aircraft, while TVOC concentrations were significantly higher in the human upper respiratory system than those detected in the breathing zones for both cases, particularly for vestibule, olfactory, sinus and nasopharynx regions. Olfactory regions were the most affected region in two cases, with an approximately 20% increase in the case of brand-new aircraft compared to an aged one. This study enlightened a novel pathway to assess indoor environment, from tracing the pollutants from the release source to ultimately quantifying the contaminant distribution characteristics in human upper respiratory system.