Antibiotic resistant bacteria is becoming a greater medical threat, with estimates suggesting that by 2050, 10 million people will die from infections that are resistant to drugs each year.

In a recent study, scientists discovered the genes that make bacteria resistant to antibiotics in polluted air in China. That does not mean people can get drug-resistant infections from the air, but the aerial spread of such genes should be the subject of further study, the researchers say. The report was published in the journal Microbiome.

In the study, researchers at the University of Gothenburg analyzed DNA sequencing from 864 different samples from humans, animals and the environment. A few of those samples came from the air in Beijing, and from those samples the researchers identified a variety of genes that can make bacteria resistant to antibiotics. What was especially concerning was that the researchers found genes that can contribute to a resistance to a group of “last resort” antibiotics called carbapenems.

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“We think this is really under-investigated and not taken seriously,” says study author Joakim Larsson, director of the Centre for Antibiotic Resistance Research at the University of Gothenburg.

Not only did Larsson and his colleagues find evidence that genes linked to antibiotic resistance can be present in the air, but they also found a high amount of the genes in areas where there’s a lot of pollution from antibiotic manufacturing. Waste from manufacturing plants can end up in water sources, as Larsson has found in other research. He says there should be more regulation when it comes to how companies dispose of their waste. “We need to apply discharge limits and have some regulation enforced,” says Larsson. “I think there’s sufficient data there to really call for some action.”

The idea that people could contract antibiotic resistant infections from smog in China got some attention recently, but Larsson says people should not overreact to the findings. Larsson says his study is not suggesting that people are getting antibiotic resistant infections from the air, but that air should be explored as a potential way for resistance to be transmitted, rather than the diseases themselves. Antibiotic resistance genes are only problematic when they are present in live bacteria.

Next, Larsson and his fellow researchers plan to study whether resistance genes can spread through air from European sewage treatment plants.

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