TABLE S-1 Air-Quality Characteristics:

Potential Health Impacts and Likelihood of Exposure Characteristic Potential Health Impacts Frequency of Exposure High Concern Cabin pressure. Serious Health Effects may occur in some people (e.g., infants and those with cardiorespiratory diseases) due to decreased oxygen pressure. Temporary pain or discomfort due to gas expansion. Health effects (e.g., airway irritation and reduced lung function) may occur at concentrations as low as 0.1 ppm with increasing severity at higher concentrations, exposure durations, and respiratory rates. Reduced cabin pressure occurs on nearly all flights. Elevated concentrations are expected primarily on aircraft without O3 converters that fly at high altitudes; substantial uncertainty exists as to frequency and duration of elevated concentrations on these flights. Reliable measurements are available; health effects in some sensitive groups are uncertain. Few systematic measurements made since the 1986 NRC report. (e.g., middle ear or sinuses) may occur. Ozone Moderate Concern Airborne allergens Carbon monoxide Inhalation can result in irritated eyes and nose, sinusitis, acute exacerbations of Headaches and lightheadedness occur at low concentrations; more severe health effects result from higher concentrations and longer durations.

Frequency and intensity of exposure sufficient to cause sensitization or

symptoms is not known.

High concentrations could occur during air-quality incidents. The frequency of incidents is highly uncertain but believed to be low. Few exposure data are available; only self-reported information on hypersensitivity responses is Reliable measurements are available for normal operating conditions; no data are available for asthma, or anaphylaxis available incidents to smoke, mists, or odors in the aircraft cabin.

products) Mild to severe health effects can result from exposure to these fluids or their

degradation products. The frequency of incidents in which these fluids or degradation products enter the cabin is very uncertain but is expected to be relatively low.

No quantitative exposure data are available. Little information is available on health effects related Infectious agents. Exposure may have no effect or cause an infection

with or without symptoms. Presence of some infectious agent is likely, but the frequency of exposures that result in infection is not known. Little information is available on the transmission of infectious agents on aircraft. Pesticides Health effects (e.g., skin rashes) can result from dermal or inhalation exposure. Exposure is likely on selected aircraft used for international flights below FAA regulatory limits. No exposure data are available; only self-reported information on health effects is available. Low Concern

1 Capable of flying at or above those altitudes, 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.

2 To ensure compliance with the O3 requirements, FAA should conduct monitoring to verify that the O3 controls are operating properly.

3 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 during ground operation, normal flight, and air-quality incidents.

4 FAA should require a CO monitor in the air supply ducts to passenger cabins and establish standard operating procedures for responding to elevated CO concentrations.

5 Because of the potential for serious health effects related to exposures of sensitive people to allergens, the need to prohibit transport of small animals in aircraft cabins should be investigated, and cabin crews should be trained to recognize and respond to severe, potentially life-threatening responses (e.g., anaphylaxis, severe asthma attacks) that hypersensitive people might experience because of exposure to airborne allergens.

6 Increased efforts should be made to provide cabin crew, passengers, and health professionals with information on health issues related to air travel. To that end, FAA and the 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 reiterates the recommendation of the 1986 NRC report that a regulation is to be established to require removal of passengers from an aircraft within 30 minutes after a ventilation failure or shutdown on the ground and to ensure the maintenance of full ventilation whenever on-board or ground-based air conditioning is available.

8 To be consistent with FAA’s mission to promote aviation safety, an air-quality and health-surveillance program should be established. The objectives and approaches of this program are summarized in Table S-2. The health and air-quality components should be coordinated so that the data are collected in a manner that allows analysis of the suggested relationship between health effects or complaints and cabin air quality.

9 To answer specific questions about cabin air quality, a research program should be established. The committee considers the following research questions to be of high priority:◦ O3. How is the O3 concentration in the cabin environment affected by various factors (e.g., ambient concentrations, reaction with surfaces, the presence, and effectiveness of catalytic converters), and what is the relationship between cabin O3 concentrations and health effects on cabin occupants?

◦ Cabin pressure and oxygen partial pressure. What is the effect of cabin pressure altitude on susceptible cabin occupants, including infants, pregnant women, and people with cardiovascular disease?

◦ Outside-air ventilation. Does the ECS provide sufficient quantity and distribution of outside air to meet the FAA regulatory requirements (FAR 25.831), and to what extent is cabin ventilation associated with complaints from passengers and cabin crew? Can it be verified that infectious-disease agents are transmitted primarily between people in close proximity? Does recirculation of cabin air increase cabin occupants’ risk of exposure?

◦ Air-quality incidents. What is the toxicity of the constituents or degradation products of engine lubricating oils, hydraulic fluids, and deicing fluids, and is there a relationship between exposures to them and reported health effects on cabin crew? How are these oils, fluids, and degradation products distributed from the engines into the ECS and throughout the cabin environment?

◦ Pesticide exposure. What are the magnitudes of exposures to pesticides in aircraft cabins, and what is the relationship between the exposures and reported symptoms?

◦ Relative humidity. What is the contribution of low relative humidity to the perception of dryness, and do other factors cause or contribute to the irritation associated with the dry cabin environment during flight?

10 The committee recommends that Congress designate a lead federal agency and provide sufficient funds to conduct or direct the research program proposed in recommendation 9, which is aimed at filling major knowledge gaps identified in this report. An independent advisory committee with appropriate scientific, medical, and engineering expertise should be formed to oversee the research program to ensure that its objectives are met and the results publicly disseminated.