The Aircraft Cabin: Environmental Quality and the Comfort and Health of Passengers and Crew

The aircraft cabin is a challenging microenvironment for maintaining the health, comfort, and well-being of passengers and crew. Space is limited, conditions can feel cramped, the outside environment is extreme, and travelers can experience anxiety because they have lost control over their situation and their environment. During flight, the passengers and crew experience noise, reduced atmospheric pressure, vibration, low relative humidity, somewhat variable temperature, and potential air quality degradation. In light of these facts, it is not surprising that passengers and crew have registered complaints about the aircraft cabin environment for decades.

Battelle recently completed Part I of a comprehensive two-part study designed to acquire cabin environmental data and to assess passenger and crew perceptions of health and comfort on a large number of flights. To measure cabin environmental variables, three instrument packages were designed and assembled. To assess passenger and crew perceptions of health and comfort in the cabin environment, two interrelated questionnaires were developed.

The questionnaires, measurement systems, and procedures were tested on four commercial flights on two participating airlines in April 2004. The cabin environment was monitored throughout each flight, from boarding through deplaning, for ozone, carbon monoxide, carbon dioxide, and volatile and semivolatile organic species, fine particles, temperature, relative humidity, air flow, vibration, noise, and light level. In addition, short-term measurements of most of these species were made in bleed air for a few minutes during each flight (bleed air is air from outside the aircraft that is processed through the engine compressors and environmental control system to supply air to the cabin).

Diagram of instrumented suitcases used to monitor environmental quality on commercial aircraft

The test flights were conducted on a 737-800 and a 757-200 aircraft, and two MD-80 aircraft. These were regular commercial flights carrying revenue passengers, and ranged in length from 3 to 4 hours. Selected findings from this Part I study are:

• Temporal and spatial temperature variations observed during the four test flights were generally minimal.
• Humidity tended to decrease during the cruise portion of the flight to a minimum value near 10%.
• Elevated levels of carbon dioxide were observed on all flights, especially during boarding and deplaning, but the levels were well within guidelines.
• Ozone was higher in the cabin during cruise than during boarding or deplaning for all flights, but on only one flight did it reach levels of concern.
• Carbon monoxide and fine particulate matter were well below levels of concern, with the exception that particulate matter was elevated during deplaning.
• Ethanol and acetone were the dominant volatile organic compounds observed on all flights; naphthalene was the most prevalent semi-volatile organic compound.
• Sound levels reached values of concern at some locations and noise was identified as an issue on a number of questionnaires.

For additional information, please contact Dr. Chet Spicer at (614) 424-5319, spicerc@battelle.org.