Impact of different ventilation strategies on aircraft cabin air quality and passengers’ comfort and well-being – the ComAir study

Indoor air quality can affect occupants in numerous ways. Especially carbon dioxide (CO2) and volatile organic compounds (VOCs) have been debated in their effects on health, well-being, and cognition of people. Aircraft cabins present indoor environments with distinctive features, where passengers are exposed to a mixture of outside and recirculated air. They include conditions such as high occupant density, inability to leave the environment, low relative humidity and need for pressurization. The ComAir study, funded by the Clean Sky 2 Initiative of the European Union, aims to investigate the impact of reducing outdoor air intake in the total volume of air supplied on cabin air quality and passengers’ well-being. The main experiment of the study uses a 2 (‘occupancy’) X 4 (‘air ventilation regime’) factorial design with stratified randomization of participants. Occupancy denotes the number of people in the aircraft (half vs. full) and varies the psychological important well-being factor of proxemics. The four air ventilation regime levels are: Baseline with typical aircraft airflows regimes per person, ASHRAE 161 requirement (standard recommendation), ASHRAE 161 half (half of the recommended flow), and a recirculation regime with a target CO2 concentration close to regulatory limit. Subjects are exposed during simulated flights in a low-pressure vessel with a mock-up of an actual airplane cabin inside. About 600 subjects are surveyed several times during the course of the flight regarding emotional state, health symptoms, sleepiness, comfort and satisfaction with environment. Additionally, a short cognitive test on information processing speed is done. Heart rate (variability) as measure of stress-related cardiovascular reactivity is continuously observed. Air quality is monitored and aligned with measurements. Experiments are conducted between November 2019 and January 2020. The experimental procedure together with preliminary results will be presented and discussed with regard to an air quality metric recommendations for aircraft cabins.