The Airliner Cabin Environment and the Health of Passengers and Crew (2002) / Chapter Skim
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4 Biological Agents
4 Biological Agents
Pages 131-181
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From page 131... ...
(see Table 4-~. Biological Agents in Outdoor Air Near the Ground Outdoor air up to an altitude of about ~ ,500 m (4,900 ft)
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From page 132... ...
~ 32 The Airliner Cabin Environment and the Health of Passengers and Crew TABLE4-l Examples of Common BiologicalAgents, Reservoirs, end Hearth Effects Related to Inhalation Exposure Agents Bioaerosol Reservoirs Possible Health Effects Aeroallergens Plant Pollen grains, plant Vegetation, settled Allergic conjunctivitis, allergens fragments dust rhinitis, sinusitis, asthma Bacterial Cells, cell fragments Growth in wafer or Hypersensitivity antigens on organic master, pneumonitis settled dust Fungal Spores, cell fragments Growth in water or Allergic conjunctivitis, on organic matter, rhinitis, sinusitis, asthma settled dust Arthropod Dust mite or Settled dust Allergic conjunctivitis, allergens cockroach excrete and rhinitis, sinusitis, asthma body fragments Mammalian Particles of cat, dog, allergens or rodent skin, saliva, dust or urine Pets, pests, settled Allergic conjunctivitis, rhinitis, sinusitis, asthma Toxins and inflammatory agents Bacterial Gram-negative Growth in water or Humidifier fever, endotoxin bacterial cells and cell on organic matter, respiratory inflammation fragments settled dust Spores, cell fragments Growth on organic Toxic and irritant effects matter Fungal toxins Biological irritants and nuisance biological agents Microbial Gases and vapors Bacterial or fungal Irritant and nuisance volatile growth on organic effects (e.g., unpleasant compounds matter or annoying odors) Carbon Gases and vapors Human breath, Perception of insufficient dioxide, body odor fresh air, irritant and body nuisance effects effluents Infectious agents Infectious Droplets' droplet Infected or Acute viral respiratory viruses nuclei of sputum, colonized persons disease, influenza, saliva, nasal or throat varicella (chickenpox)
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From page 133... ...
of the bleed air used for ventilation are likely to alter allergenic proteins and inactivate microorganisms that still are viable when they enter an aircraft through an outside air intake (Withers and Christopher 2000~. Therefore, in flight, biological agents in aircraft cabins arise virtually exclusively from inside sources rather than from the intake of outside air.
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From page 134... ...
Most microorganisms that have been isolated from occupied spaces, including aircraft cabins, are human-source bacteria shed from exposed skin and scalp and from the nose and mouth. These microorganisms are found normally on the human body (they are normal flora)
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From page 135... ...
The Air Carrier Access Act (ACAA, ~ 4 CFR 3 82, Nondiscrimination on the Basis of Disability in Air Travel) protects the rights of air travelers with disabilities and requires that air carriers permit passengers to fly with their service animals in the cabin.
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From page 136... ...
Although some of the fungi in settled dust carry allergens and some of the bacteria have inflammatory properties, very few of these microorganisms are infectious, or they cause infection only in severely immunosuppressed persons. Microbiological Growth Most ofthe fungi and environmental bacteria in aircraft cabins enter with outside air while aircraft are on the ground or are earned in by the occupants (e.g., on their shoes, clothing, or hand luggage)
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From page 137... ...
Therefore, passengers and cabin crews should have no opportunity for exposure to legionellae curing air travel. The cockpit crew may tee exposedto aerosolizedbacteria if the water in a humidifier is contaminated and the unit is one that generates a water mist, but contamination of water used in humidifiers or for drinking is unlikely if the water storage tanks on aircraft are well maintained and the water supply is clean.
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From page 138... ...
establish a program for the systematic measurement of microbial aerosols on a representative sample of routine commercial flights. In the last ~ 5 years, eight investigations of biological agents in aircraft cabins have sampled a total of more than 200 domestic and international flights on multiple airlines and ~ 7 types of aircraft of various ages and designs (Table 4-2~.
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From page 140... ...
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From page 141... ...
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From page 144... ...
Sampling for Allergens Few studies have measured the concentrations of allergens in aircraft cabins. (The allergen content of settled dust is reported as the amount of an agent per unit amount of settled dust—typically micrograms per gram (pg/g)
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From page 145... ...
Evaluation of Available Information on Bioaerosols Data on some biological agents in commercial aircraft cabins now are available as a result of the studies (see Tables I -2 and 4-2) that were conducted after the publication ofthe previous NRC report ARC ~ 986~.
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From page 146... ...
Because of a lack of data, it is not yet possible to determine whether endotoxin concentrations in aircraft cabins are high enough to be associated with adverse health effects. An ongoing NIOSH study is expected to provide relevant data on endotoxin concentrations in aircraft cabins (Waters et al.
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From page 147... ...
Recommended Sampling for Biological Agents Bioaerosol sampling on commercial aircraft has been broadly based. If the prevalence of biological agents in the cabins of commercial aircraft is to be understood, rigorous studies focused on specific biological agents are needed.
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From page 148... ...
It was also recommended that studies of aircraft air quality not include endotoxin, fungal toxins, or other microbiological agents (e.g., fungal glucans) until assays for these materials are better developed and more evidence is available to suggest that these compounds are present in aircraft cabins at concentrations sufficient to cause adverse health effects.
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From page 149... ...
Release of tracer particles and modeling of particle dispersion in aircraft cabins also may play a role in the assessment of the spread of infectious agents and other biological materials generated by cabin occupants and their activities. NIOSH is modeling airflow and migration of airborne biological agents throughout typical aircraft cabins.
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From page 150... ...
This section addresses the allergens of greatest potential concern in aircraft cabins, describes investigations that have been conducted of possible exposures to infectious agents on aircraft, and describes how exposures to biological agents in aircraft cabins can be controlled. Hypersensitivity Disease immediate hypersensitivity involves stimulation of immunoglobulin E ~gE)
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From page 151... ...
travel in the cabins of commercial aircraft rather than the cargo bays. Thus, it is not surprising that cat and dust mite allergens have been detected in aircraft cabins (Wickens et al.
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From page 152... ...
Infectious Disease The first NRC report on air quality in aircraft cabins included several recommendations for reducing the risk of transmission of infectious agents.
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From page 153... ...
Furthermore, the consequences of exposure to infectious agents may extend beyond the travelers to all others with whom they later have contact. Those factors give substantial public-health significance to the relationship between infectious diseases and air travel (Sato et al.
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154 Ct · _ o o · _ cn .s An U)
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155 ~ `:: ~ 3 ~ ~ ~ _ cn ~ ~ ~ O ~ ~ g 3 3 3 ~ X ~ ~ X 3 Us .
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From page 156... ...
, or exposure during air travel ishighlyunlikely~e.g., v~ralhemorrhagic fevers or pneumonic plague) (Clayton et al.1976; Fritz et al.1996; Wenze} 1996; Withers and Christopher 2000; Maloney and Cetron 200 I; Weiss 200 ~ )
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From page 157... ...
The FAA will advise air carriers ofthe need to deplane passengers, if possible, after 30 min without ventilation" (DOT 1987~. Suspected transmission of influenza associated with air travel also has been reported in association with an aircraft that had an operating ventilation system and no ground delay (Klontz et al.
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From page 158... ...
Measles remains a common disease in many countries, including some developed countries in Europe and Asia, making exposure due to air travel a possibility. Measles and Air Travel Suspected transmission of measles at an airport and between passengers who shared a domestic flight has been reported (CDC ~ 983)
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From page 159... ...
is caused by Mycobacterium tuberculosis, a bacterium that can attack any part ofthe body but most frequently is associated with pulmonary infection. People typically become infected after spending a long time in a closed environment where the air is contaminated by a person with untreated tuberculosis who is coughing and has numerous organisms in secretions from the lungs (CDC 2001b)
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From page 160... ...
. Tuberculosis is the most thoroughly studied communicable disease possibly associated with transmission during commercial air travel (Driver et al.
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From page 161... ...
. However, air travelers who make frequent and regular stops in countries and areas with a high tuberculosis burden may be advised to have a baseline skin test to determine theirinfection status (CDC 2001 b)
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meningitidis. Meningococcalf Disease and Air Travel Persons with meningococcal disease are known to have traveled on commercial aircraft (Duffy 1993; CDC 200 I c)
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. CONTROL OF EXPOSURES TO BIOLOGICAL AGENTS Hypersensitivity Diseases, Toxins, and Nuisance Agents As discussed earlier, extensive microbiological growth in aircraft cabins appears to be unlikely.
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From page 164... ...
Persons with communicable diseases that do not pose a direct threat to the health or safety of others cannot be denied access to air travel ( 14 CFR 3 82, Nondiscrimination on the Basis of Disability in Air Travel) , although air carriers can impose restrictions (e.g., the wearing of a face mask)
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2001~. Selection of additional immunizations for travelers should be based on the requirements ofthe local health authorities at the travel destination and individual travelers' risk of infection.
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From page 166... ...
Airlines typically maintain passenger manifests and other records for 2-7 A, after which they are archived or destroyed. However, this period may be too short to allow follow up of infectious diseases with incubation periods longer than one wk (e.g., tuberculosis, measles, end possibly meningococcal disease)
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From page 167... ...
This observation, in conjunction with the available evidence that only persons seated near a source person are exposed to a sufficient number of bacteria or viruses to become infected, indicate that bioaerosols as small as dropletnuciei are readily entrained in moving air streams (see Figure 2-31. Therefore, the movement of bioaerosols along the length of aircraft cabins is likely restricted, and particles, including bioaerosols, are removed from the cabin with the exhaust or return air (see section on ventilation practices in aircraft cabins in Chapter 2~.
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From page 168... ...
Nevertheless, increasing outside air ventilation or the amount of filtered recirculated air would decrease the mathematical probability of disease transmission in aircraft cabins by diluting airborne viruses or bacteria in a larger volume of microorganism-free air (see Equation 2-~. Although increasing cabin ventilation rates or changing the air mixing patterns are unlikely to prevent the transmission of infectious agents entirely, aircraft cabins should be provided with at least the minimal recommended supply of outside air wherever passengers are onboard.
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From page 169... ...
CONCLUSIONS ~ A person's risk of acquiring an infection on an aircraft depends on several factors, such as the presence of an infectious person and release of infectious agents by that person, the ventilation rate and mixing of cabin air, the amount of air that is recirculated and how it is treated, proximity to the source person, duration of exposure, and susceptibility to the specific infectious agents. These factors could also increase inhalation exposure to allergens and other potentially hazardous biological materials generated by passengers and activities within aircraft cabins.
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From page 170... ...
can be determined better when the results of current studies become available. Dust samples from commercial aircraft cabins have been analyzed for allergens and cat and dust mite allergens have been detected.
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From page 171... ...
Public health authorities and air carriers should cooperate to notify air travelers as soon as possible if they may have been exposed to an infectious agent for which postexposure prophylaxis may reduce the risk or the severity of an infection. Airlines should ensure that electronic passenger manifests and contact information is preserved and readily available for a period of at least one month following disembarkation to facilitate timely identification and notification of passengers who may have been exposed to an infectious agent during air travel.
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From page 172... ...
1994. Airline Cabin Air Quality Study.
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From page 173... ...
1995. Exposure of passengers and flight crew to Mycobacterium tuberculosis on commercial aircraft, 1992-1995.
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1999a. Dust mite allergens are carried on not only large particles.
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From page 175... ...
1994. Transmission of Mycobacterium tuberculosis associated with air travel.
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1987. Risk of acquiring respiratory tract infection during air travel.
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From page 177... ...
1999. Indoor air quality investigation on commercial aircraft.
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1993. Exposure to Mycobactenum tuberculosis during air travel.
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From page 179... ...
1992. Measurement of cabin air quality aboard commercial airliners.
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From page 180... ...
2001. Cabin Air Quality Exposure Assessment.
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From page 181... ...
1998a. Tuberculosis and Air Travel: Guidelines for Prevention and Control.
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