Editor's Note: The headline and lede of this story were updated on March 13, 2024 at 1:40 p.m. E.S.T. to remove reference to the total amount of plastic inhaled by humans every week. Researchers originally estimated that humans ingest a credit cards' worth, but this was a miscalculation; it's actually much lower than that.
In 2019, a team of scientists estimated that up to 16.2 bits of microplastic enter our airways every hour. Now, researchers have built on these findings to figure out how the plastic moves around our respiratory systems. "For the first time, in 2022, studies found microplastics deep in human airways, which raises the concern of serious respiratory health hazards,” first author Mohammad S. Islam, a senior research fellow at the University of New South Wales, Sydney, said in a statement.
By analyzing this circulation under slow- and fast-breathing conditions with three possible plastic shapes , the researchers found that the biggest chunks of microplastic — those measuring about 5.56 microns — were the ones most likely to get lodged. The places these larger chunks tended to go were in the upper airways, such as in the nasal cavity and the back of the throat.