Researchers used Hurricane Larry to prove ocean microplastics can be swept inland as air pollution

As Hurricane Larry lashed Newfoundland in 2021, university students from Halifax headed to a rural area in its track to find out whether the ocean might whip microplastics up into the atmosphere then transport them by air to otherwise pristine communities.

The results, you could say, blew their socks off.

"It was such, like, an astonishing result that we weren't really expecting," said Anna Ryan, a Dalhousie University environmental science masters student and the study's lead researcher. 

To test their theory, the 24-year-old and another student set out a large glass cylinder — essentially trying to collect air — near St. Michaels, a community of less than 300 on Newfoundland's Avalon Peninsula. The vessel was in place for six hours at a time, collecting samples from before, during and after the September storm.   

The highest concentration of microplastics were found in samples collected during the hurricane: more than 100,000 particles per square metre per day, an amount Ryan called far higher than has been found in any other study of atmospheric microplastics. Their study was published last week in Nature, a leading science journal.

Microplastics are tiny pieces of plastic, less than five millimetres in length, that come from the degradation of larger plastic products or the shedding of particles from water bottles, plastic packaging and synthetic clothes.

Ryan said the ocean is often thought of as the "ultimate sink" for microplastics. But that may not be where the plastics stay. 

She said microplastic pollution is a growing concern that has been detected in all environments around the globe. It is a risk to human and animal health, as well as overall ecosystem health, though the extent of that harm is still not well understood. 

The particles Ryan's team collected were so small they cannot be seen with the naked eye, about 20 to 30 times smaller than the width of human hair, she said. 

"You could say that the smaller they are, the bigger the risk they are because they're so small, they're really easily ingested or inhaled," she said, during a recent interview at a Dalhousie lab. 

Her research paper notes Hurricane Larry, which made landfall as a Category 1 storm, followed a track far offshore of the eastern seaboard of the United States and Eastern Canada, maintaining its trajectory over the ocean before making landfall in Newfoundland. 

This made the weather event a unique opportunity for the researchers.

The hurricane did not travel close to any major urban areas, which are generally considered a major source of airborne microplastics.

It did, however, pass over ocean areas — including the North Atlantic "garbage patch" located south of Newfoundland —where currents trap high concentrations of plastics in the surface waters, the study says.