Carbon dioxide in passenger cabins: Spatial temporal characteristics and 30-year trends

Carbon dioxide (CO₂ ) is an important environmental parameter in aircraft cabins. To understand the most recent, real-time CO₂ concentration levels and their key influencing factors in aircraft cabins, we conducted in-flight measurements of 52 randomly selected commercial flights with different aircraft types and durations from August 2017 to August 2019. The spatial temporal characteristics of CO₂ concentrations on board were analyzed and summarized. For the flight time scale, the CO₂ concentrations during the boarding phase (1680 ± 558 ppmv) were notably higher than that in other phases, whereas the condition of the cruising phase was the lowest in most flights. The flight average CO₂ concentrations of the cruising phase were 1253 ± 164 ppmv, and the corresponding estimated outside airflow rates were 6.2 ± 1.3 L/s/p in the economy class across all flights. Single-aisle and twin-aisle flights did not show noticeable differences for the same phases. Relatively uniform CO₂ concentrations were observed at different positions of the same class. By comparing the results of this study with those previously reported, CO₂ concentrations showed a slightly decreasing trend over the last 30 years. This suggested a slightly increased ventilation rate and potentially superior air quality on board.