If you've ever sat next to a sneezing, coughing guy on a crowded airplane, stewing about how he was going to ruin your vacation by spraying viruses and bacteria all over you, here's something to take your mind off your worries.
But not in a good way.
Researchers from Auburn University took two common, nasty bacteria and, in a lab, painted them on six surfaces that passengers routinely touch inside airplane cabins. The results are not heartening. Methicillin-resistant Staphylococcus aureus (MRSA) lasted for 168 hours on the cloth seatback pockets where flyers store everything from magazines to iPhones. And a virulent strain of E. coli, which can cause severe abdominal cramps and vomiting, persisted for 96 hours on armrests, 72 hours on tray tables and 48 hours on that metal button you use to flush the toilet in airplane lavatories.
Researchers simulated the temperature (24 degrees Centigrade) and humidity (a dry 18 percent) in an airline cabin, and suspended the bacteria in three different solutions: saline, simulated sweat and simulated saliva. They did not test the cleaning protocols employed by airlines, because their assignment was to collect baseline data for the Federal Aviation Administration.
So I guess your comfort with this revelation, which was presented last week at the American Society for Microbiology meeting, boils down to how confident you are in the thoroughness of the cleaning crew that comes on board while you're switching planes on a layover. Or how strong your immune system is. Or how successful you are at keeping your hands away from your face on a long trip.
"The take-home message is be careful about your hand hygiene and don't travel while contagious or immune compromised," said Kiril Vaglenov, a post-doctoral fellow in materials science at Auburn, who led the research.
MRSA is the scourge of locker rooms, hospitals, military barracks and other settings where large numbers of people congregate. But it's also carried in the nostrils of about 1 percent of the U.S. population. About 30 percent of people carry the non-methicillin resistant strain of the same bacteria.
As you might expect, transmission of the pathogens was easier from non-porous surfaces such as tray tables and window shades, even though they lasted longer on porous surfaces such as seat back pockets and arm rests. The good news is that after just 24 hours, the transmission rate of MRSA in sweat and saliva was very low, just 1.1 percent and 0.4 percent respectively, and it dropped to zero after 48 hours. From tray tables and window shades, however, transmission was as high as 44.4 percent for MRSA in sweat.
Transmission of E. coli in sweat on tray tables remained very high even after 72 hours, but was at zero within the same time period for armrests and toilet handles.
This study comes on the heels of research presented at the same conference that found that the bacteria that causes Legionnaires' disease flourishes in some windshield washer fluid, which can become aerosolized and be inhaled.
Mr. Vaglenov, meanwhile, said people need to be aware of how prevalent pathogens are in their environment and how often they come in contact with them. Of airline-borne bacteria, he said: "I don't think it's more dangerous than being at the movie theater."