Just like any other public infrastructure, subway cars are teeming with millions of germs and microbes.
On the Boston subway system, however, the case may be different.
Known as the T, the Boston subway is still laden with bacteria, but new research suggests that the microorganisms accompanying passengers are no different from the organisms found in the normal human skin.
In other words, they're actually harmless.
Investigating Subway Cars
Researchers from the Harvard T.H. Chan School of Public Health took 100 microbial samples from hanging straps, seats and ticket machines across six types of different train surfaces.
After sequencing and analyzing the swabs, scientists found that microbes influencing antibiotic resistance were in lower levels compared to what can be found on the human gut.
"They're exactly what you'd run into shaking somebody's hand," says Curtis Huttenhower, senior author of the study.
The highest amount of microbes was detected on hanging grips, followed by seats and touch screens.
All of the train surfaces were dominated by microbes from normal human skin, with the bacterial species Proteobacteria, Firmicutes and Actinobacteria responsible for more than 20 percent of the microbial community.
There were low levels of oral and gut microbes such as Lachnospiraceae, or those microbes from the Prevotella and Veillonella families.
Graduate student Tiffany Hsu, lead author of the study, says she did not expect the hanging grips to have much DNA on them because they are relatively small and are not used often.
However, she says porous surfaces can accumulate microbes more efficiently than solid objects such as a metal pole.
Why The Findings Are Important
The findings of the study could provide an early warning system for the outbreak of public health threats such as a rise in antibiotic resistance or a flu outbreak.
Huttenhower says their study can establish a baseline against deviations that can be used to monitor public health.
Furthermore, Huttenhower and his team were quite surprised to see how "normal" the samples looked. He says that even when they looked closely, there was nothing dangerous or unusual about the microbial samples.
In the absence of something like the flu season, he says it shows that all of the germs you run into on the Boston Subway are typical.
Harvard researchers are not saying that their findings apply to other subway systems outside Boston, but they do hope that the findings can be used to better design public spaces to contain outbreaks.
Meanwhile, Huttenhower and his team will determine which microbes are dead or alive and which ones can be transferred between people. Details of the new study are published in the journal mSystems.
Photo: Alan Light | Flickr