Black carbon, a component of soot and one of the primary air pollutants driving climate change, has been detected on the fetal side of the placentas of pregnant women, suggesting air pollution can reach fetuses, concludes a new study published in the journal Nature Communications.

The finding builds on 2018 research that found black carbon within the placenta of pregnant women, but did not establish whether the particles could cross the life-sustaining organ to reach the fetus it protects. The study also follows a recent, comprehensive review of research that has concluded air pollution has an effect on every cell, organ, and function of the human body, from reproductive organs and fertility to brains and cognition to hearts and circulation.

“This is the most vulnerable period of life. All the organ systems are in development. For the protection of future generations, we have to reduce exposure [to pollution],” Tim Nawrot, PhD, a professor at Hasselt University in Belgium and the study’s lead author, told The Guardian.

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The finding has particular relevance in India, home to 22 of the world’s top 30 polluted cities, as the research took place in the German town of Hasselt, which doesn’t even make an appearance in the world’s top 500 most polluted cities list. This town, according to The Guardian’s report, has pollution levels lower than the European Union limit, though higher than the World Health Organization limit. The study examined 25 placentas from non-smoking women and used laser technology to detect black carbon particles. In every placenta, researchers found nanoparticle pollution, though the volume of pollution varied between the location of mothers’ homes; women who lived near main thoroughfares with more traffic had higher levels of pollution concentrated in the fetal side of the placenta. In Indian metros, where pollution is overall much higher and omnipresent — in bylanes and on main drags — the potential quantity of air pollution that crosses placentas could be much higher; no Indian research into the topic has occurred yet, however.

The team also found pollution particles in the placentas of 12-week-old, miscarried fetuses; previous research has linked air pollution to poor pregnancy outcomes including miscarriage, premature birth, and low birth weight.

The team is currently working to confirm the presence of black carbon pollution in fetal blood. But even if the contamination is confirmed, researchersoffer little hope.

“It is really difficult to give people practical advice because everyone has to breathe,” Nawrot told The Guardian. “But what people can do is avoid busy roads as much as possible. There can be very high levels next to busy roads, but just a few meters away can be lower.”