China's smog could make it more difficult for people to fight off some infections. The air pollution has traces of antibiotic-resistant bacteria.
A team from the University of Gothenburg in Sweden took over 800 samples of DNA from humans, animals and various environments across the globe.
In Beijing, the air samples contained DNA from genes that make bacteria resistant to some "of the most powerful antibiotics we have" — including carbapenems.
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Carbapenems are a sort of "last resort" antibiotic doctors can prescribe to treat certain infections caused by resistant bacteria.
The team notes there's probably a mix of live and dead bacteria in the air. And it's the live bacteria that could be "a real threat."