Concentrations of Selected Chemical Species in the Airliner Cabin Environment

Reported here are the concentrations of carbon monoxide (CO), carbon dioxide (CO2), fine particulate matter (PM2.5), ozone (O3), and volatile organic compounds (VOC) measured in the cabin and bleed air, and semivolatile organic compounds (SVOC) measured in only the cabin air, on four different commercial airliners in revenue service within the continental United States. Sampling was conducted over various time intervals including boarding, takeoff, cruise, and descent. Bleed air CO was never measured above the instrument detection limit of 2 ppm, and cabin CO only exceeded the detection limit briefly on one flight. The concentration of CO2 in bleed air was at ambient background levels for all flights, and cabin concentrations of CO2 were always well below the 5000 ppm Federal Aviation Administration standard. PM2.5 concentrations were well below levels of concern, with the exception of boarding and deplaning during one flight only. Ozone was present at elevated levels in bleed air compared to cabin air, and was higher in the cabin during cruise than during boarding or deplaning for all four flights. Ozone cabin air/bleed air concentration ratios ranged from 0.37 to 0.80, and on one flight the cabin ozone concentration exceeded the National Ambient Air Quality Standard (NAAQS) of 0.12 ppm for over one hour, and nearly exceeded the FAA standard of 0.1 ppm for a three-hour average. Ethanol and acetone were the dominant VOCs observed on all flights; other VOCs, such as toluene, tetrachloroethene, and 1,4-dichlorobenzene were found, but at significantly lower concentrations. The polycyclic aromatic hydrocarbons naphthalene, acenaphthene, and phenanthrene were found in the cabin air on all flights. Other SVOCs, such as the pesticide permethrin, were detected, but isomers of tricresyl phosphate were not. Concentrations reported here are compared to applicable regulatory standards and to similar measurements performed during previous cabin air quality studies.