NRC Urges More Work On Cabin Air Quality
Air Line Pilot, January/February 2002, p. 5
By Jan W. Steenblik, Technical Editor
In December 2001, the National Research Council published a 220-page report, "The Airliner Cabin Environment and the Health of Passengers and Crew." The report concluded that the environmental control system (ECS) on the typical jet airliner, "when operated as specified by the manufacturer, should provide an ample supply of air to pressurize the cabin, meet general comfort conditions, and dilute or otherwise reduce normally occurring odors, heat, and contaminants."
The report noted, however, that "the current design standard of a minimum of 0.55 pounds of outside air per minute per occupant (FAR Part 25.831) is less than one-half to two-thirds the ventilation rate" the American Society of Heating, Refrigerating, and Air Conditioning Engineers recommends for buildings.
Acknowledging that "establishing a causal relationship between cabin air quality and the health complaints of cabin crew and passengers is extremely difficult," the NRC’s Committee on Air Quality in Passenger Cabins of Commercial Aircraft ranked a number of air-quality characteristics according to their potential risks to health and called for more research.
Of "high concern," the report said, are cabin pressure (decreased partial pressure of oxygen) and ozone (O3).
NRC listed airborne allergens, carbon monoxide (CO), hydraulic fluids, engine oils, infectious agents, and pesticides as issues of "moderate concern."
In the "low concern" category were carbon dioxide (CO2), deicing fluids, nuisance odors, and relative humidity.
The report included a number of recommendations. The principal ones are summarized below.
1. The FAA should publicly prove that current and proposed FARs related to cabin air quality are adequate. "If a specific standard is found to be inadequate to protect the health and ensure the comfort of passengers and crew, [the] FAA should revise it." NRC also recommended that an operational standard for ventilation consistent with the design standard be established.
2. The FAA should ensure that all flights meet the current FAR limits for cabin O3, regardless of altitude. The FAA also should require that O3 converters be installed, used, and maintained on all aircraft capable of flying at or above altitudes specified in the FARs, or strict operating limits be set with regard to altitudes and routes for aircraft without converters to ensure that the O3 concentrations are not exceeded in reasonable worst-case scenarios. The FAA should monitor operators to verify that the O3 controls are working properly.
3. The FAA "should investigate and publicly report on the need for and feasibility of installing air-cleaning equipment for removing particles and vapors from the air supplied by the ECS on all aircraft to prevent or minimize the introduction of contaminants into the passenger cabin…."
4. The FAA "should require a CO monitor in passenger-cabin air-supply ducts and establish standard operating procedures for responding to elevated CO concentrations."
5. Because some people may suffer serious health effects from exposure to allergens, the FAA should consider prohibiting small animals in aircraft cabins. Also, cabin crews should be trained to recognize and respond to severe, potentially fatal responses (e.g., anaphylaxis, severe asthma attacks) that hypersensitive people might suffer from exposure to airborne allergens.
6. "Increased efforts should be made to provide cabin crew, passengers, and health professionals with in-formation on health issues related to air travel…. [The] FAA and airlines should work with such organizations as the American Medical Association and the Aerospace Medical Association to improve health professionals’ awareness of the need to advise patients on the potential risks of flying, including risks associated with decreased cabin pressure, flying with active infections, increased susceptibility to infection, or hypersensitivity."
7. The committee reiterated a 1986 NRC recommendation that the FAA require operators to remove passengers from an aircraft within 30 minutes after a ventilation failure or shutdown on the ground and to ensure continuous full ventilation whenever on-board or ground-based air conditioning is available.
8. The FAA should establish an air-quality and health surveillance pro-gram, collecting data "in a manner that allows analysis of the suggested relationship between health effects or complaints and cabin air quality."
9. A research program should be established to answer specific questions about air quality.
10. The committee recommended that Congress designate a lead federal agency and provide enough money to conduct or direct the research program. An independent advisory committee with appropriate scientific, medical, and engineering expertise should be formed to oversee the research program.
ALPA’s Aeromedical Committee is reviewing the NRC report and expects to provide its own recommendations to the FAA.