Measurements of Indoor Air Quality on Commercial Transport Aircraft

Exposures to cabin environmental contaminants were measured on 36 commercial transport aircraft. The objectives were to characterize levels of contaminants and evaluate the relationship between flight factors such as aircraft size, occupancy, ventilation, and flight length, and environmental parameters. Monitoring was conducted at two coach locations for the duration of the flight for VOCs, nitrogen oxides, CO, CO2, O3, temperature, relative humidity, total particulates, and barometric pressure. Five-minute average concentration ranges were: CO2 515-4902 ppm; O3 <0.05-0.24 ppm; CO <0.2-2.9 ppm; nitrogen oxides <0.05-2.0 ppm; and total particulates <0.028-0.197 mg/m. Gate-to-gate average concentrations of VOCs were: toluene <3-130 ppb, limonene <3-12 ppb, and ethanol <0.8-2.4 ppb. Carbon dioxide exposures were highest on shorter and high-occupancy flights, aircraft with greater recirculated-to-fresh-air ratio, and narrow-bodied aircraft. In general contaminant levels were low compared to standards. Carbon dioxide levels indicated lower ventilation rates per occupant than most other indoor environments. INDEX TERMS Cabin air quality, Aircraft, Ventilation, Carbon dioxide, Relative humidity INTRODUCTION Much scientific and public interest has focused on cabin air quality in aircraft, which is the workplace of approximately 198,000 flight personnel in the US (Air Transport Association, 2000). Cabin air contaminants may include carbon dioxide, products of combustion such as carbon monoxide, nitrogen oxides, particulates and aldehydes, organic hydrocarbons from engine oil, fuel, hydraulic fluids, de-icing agents, cleaning products, allergens and infectious agents such as viruses and bacteria. Engine compressor bleed air is pre-conditioned, sent to the air conditioning packs, and delivered to the cabin through a manifold that permits mixing with recirculated cabin air. Outside air is not filtered but the recirculation system incorporates air filtration; types and efficiency of filters vary by aircraft. Recirculation maintains air supply rate and minimizes use of more costly bleed air. While outside supply air at aircraft altitudes is generally very clean, it may become contaminated with engine oil, fuel, and hydraulic fluids aloft. During ground operations hydrocarbon vapors from refueling and other outdoor pollutants may enter the ventilation system (van Netten and Leung, 2000). Ozone may enter the cabin when an aircraft flies through the ozone layer. Although aircraft are equipped with catalytic converters to destroy ozone in bleed air, catalyst age may degrade efficacy. * Contact author email: [email protected] Proceedings: Indoor Air 2002