Measurements of volatile organic compounds in aircraft cabins. Part II: Target list, concentration levels and possible influencing factors

To better understand the overall VOC levels and their key influencing factors in aircraft cabin, we conducted in-flight measurements in 51 randomly selected flights by quantitative methods that were previously introduced in part I of this research program. Of those 51 flights, several potential influencing factors, including flight phases (N = 51), meal services (N = 22) and air supply (N = 13) were analyzed by statistical and contrastive methods. Based on the statistical results, two detailed case studies on peak values and air supply during flights further indicate the source fluctuation characters of different VOCs. Key conclusions derived from this study include: 1) Combined with qualitative results on some specific VOC species with high detection rate in part I, a list of 29 compounds were proposed as target VOCs in cabin air. 2) Most target VOCs had significant differences (p < 0.05) with their concentration levels at three different phases of the tested flights. 3) In-flight measurements indicated that peak values commonly occurred during before take-off and cruise phases. The effect of meal service was considered to be limited due to its short service duration in spite of its dominant contribution to the concentration increase of total VOCs during meal time. 4) Concentration levels of some specific VOCs in supply air were significantly lower than those in recirculated air (p < 0.05), indicating the evident dilution effect of bleed air on cabin VOCs. This study could help to better understand cabin air quality and its major influencing factors.