Effects of reduced pressure on the reaction between ozone and limonene in a simulated aircraft cabin environment.

High ozone concentrations often exist under the reduced pressure conditions observed in aircraft cabins during flight. In this study, we measured the concentrations of the products obtained from the reaction of ozone with limonene in a simulated aircraft cabin environment (i.e., vacuum chamber at approximately 70 kPa). The concentration of total volatile organic compounds increased under reduced pressure when compared to that under atmospheric pressure, whereas the ozone concentration decreased during the hour after limonene was injected into the chamber. These changes can be partially explained by the increased evaporation of limonene under reduced pressure. With respect to secondary products, a decrease in particulate matter was observed under reduced pressure for an initial ozone concentration of 0.4–0.5 mg/m³. In contrast, the effects of reduced pressure on the concentrations of gaseous products, such as formaldehyde and limonene oxide, were small when the initial ozone concentration was approximately 0.3 mg/m³. These results indicate that the reaction between limonene and ozone under reduced pressure is similar to that occurring under atmospheric pressure. Image 1 • In aircraft cabins during flight, ozone often exists under the reduced pressure. • We simulated ozone and limonene reaction under reduced pressure in a chamber. • Particulate matter generation inhibited under reduced pressure. • Effects of reduced pressure on the concentration of gaseous products were minor. • Ozone/limonene reaction was similar under atmospheric and reduced pressures. [ABSTRACT FROM AUTHOR]