Research: Harmful bacteria in planes, buses still a worry

August 15, 2014

AUBURN, Ala. — The director of a university study investigating how long illness-causing bacteria can survive in the cabins of airliners says motorcoaches may be an even more fertile environment for disease-causing bacteria than planes.  

Auburn University Prof. Jim Barbaree has been leading a research team from the university that has spent months investigating how long pathogens that cause diseases can survive in a jetliner.  

What they found was that dangerous bacteria can linger on surfaces in commercial airplane cabins for up to a week, according to the research Barbaree’s team presented at the annual meeting of the American Society for Microbiology.

When asked whether motorcoach cabins provided a more or less conducive atmosphere for illness-causing bacteria, Barbaree responded without hesitation, saying “bacteria probably grows more on a bus.”

The reason?

Humidity and heat.  Bacteria thrive in higher humidity and temperature environments.

The relative humidity in airline cabins is consistently 20% or less, which is why health experts recommend travelers drink plenty of liquids when flying.

Second, airline cabins are more consistently kept at “room temperature.”

The relative humidity of bus interiors, on the other hand, more closely reflects that of the outside environment, which in most areas of the country is well above 20 percent, and the temperature of motorcoach interiors can fluctuate widely, depending on utilization and weather conditions, but is often well above room temperature.  

The Auburn research team under Barbaree’s direction took samples from six airline cabin materials -- an armrest, plastic tray table, a metal toilet button, a window shade, the cloth from a seat pocket, and seat leather -- and applied or injected them with methicillin-resistant Staphylococcus aureus, or MRSA, and E. coli O157:H7, bacteria that can cause serious illness or even death.  

Auburn Department of Biological Sciences graduate student Kiril Vaglenov conducted much of the research during the two-year study -- funded through the Federal Aviation Administration Airliner Cabin Environmental Research Center -- to determine how long the E. coli and Staphylococcus bacteria would survive on commonly touched surfaces under typical airplane conditions.  A major airline supplied Vaglenov and the other researchers with the materials from the airplane cabin.  “Our data show that both of the bacteria can survive for days on these surfaces, particularly the porous material such as armrests and seat pockets,” said Vaglenov.  

“Air travelers should be aware of the risk of catching or spreading a disease to other passengers and practice good personal hygiene.”

For bacteria to be transmitted from a cabin surface to a person, it must survive the environmental conditions in the airplane.  In the study, Vaglenov simulated the temperature and humidity levels typically found during commercial flight.  

MRSA survived the longest -- 168 hours;  that’s a full week -- on material from the seat-back pocket, while E. coli O157:H7 lived for 96 hours (four days) on the material from the armrest.

“The point of this study is not to be an alarmist, but to point out to the airlines the importance of providing a sanitary environment for travelers,” said Prof. Barbaree.  “We want to work with them to minimize the risks to human health.”

The Auburn team is currently investigating how long pathogens that cause other diseases, such as tuberculosis, can survive in an airplane environment.  

Vaglenov said future steps include exploring effective disinfecting procedures and testing other surfaces and materials that have antimicrobial properties to determine if they can help reduce health risks.

For example, the use of seat fabrics that are impregnated with microbe fighting chemicals.

Barbaree has a couple of recommendations for reducing illness-causing bacteria from airplane and bus interiors.  

No. 1, because pathogens are more easily picked from nonporous materials that many passengers touch, like hand rails and plastic armrests, these metal and plastic surfaces should be sanitized with every bus cleaning.

Second, develop a good disinfecting protocol.

For passengers, alcohol wipes or a hand sanitizer should be used when traveling, and the touching of nose, mouth and eyes avoided.

Bus & Motorcoach NEWS Issue, August 15, 2014

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