Temporal variations of ultrafine particle concentrations in aircraft cabin: A field study

Abstract

Characterization of indoor aerosols in aircraft cabin has been of great interest. However, few studies have presented investigations of ultrafine particle (UFP) concentrations in actual aircraft cabin environment. In this study, we presented the characteristics of UFP number concentration levels, size distributions and temporal variations in fourteen randomly selected domestic commercial flights in China. The results showed that the concentration levels of UFPs in cabin air were 417 ± 1089 counts cm−3, with the lowest values occurred during cruising phase, and the dominant peak at the size channel of 72–100 nm in general. Some of the peak values were observed at the moments of turbulence of air stream or passing through cloud. To further identify contributions of UFPs from interior and outside cabin, CO2 in return air was simultaneously observed as a ventilation tracer to calculate the total airflow rates in those flights. A simplified model was developed to estimate the contribution rates of UFPs from bleed air and cabin interior at cruising phase in selected flights, combing with mass conservation equation under some assumptions. It indicated that, UFPs were commonly derived from unfiltered bleed air system in most of those flights at cruising phase. However, some exceptions were found in some flights, possibly due to unfiltered bleed air system and in-cabin ozonation. This study could be a reference for further understanding the status quo and control strategies of ultrafine particulate pollution in commercial aircraft cabins.