A combination of sewage overflows and coastal winds could be sending billions of airborne microplastic particles into the world’s coastal towns and cities, where they could be breathed in by local residents leading to a range of detrimental effects on human health.

This is the suggestion of a new study led by researchers at Plymouth Marine Laboratory who have now – in light of the findings an our understanding of the impact of microplastics on human health – called on the UK government for legislation forcing water companies to remove micro and nanoplastics from their wastewater.

The study analysed two years’ data on combined sewer overflows into Plymouth Sound, alongside same day and long-term meteorological and satellite data to assess how often the right conditions to transfer microplastic particles from water to air occurred.

The researchers found that on 178 days within the two-year period, sewage spills from land to sea coincided with winds of at least 6.5 metres per second pushing back to shore and towards the city of Plymouth.

The researchers suggest that this could have resulted in microplastics and nanoplastics – both known to be discharged through sewage spills – being lifted from the sea. According to the meteorological data, this could have happened during almost 1,600 hours of the period studied.

It’s further suggested that once there, the airborne particles could have been breathed in by local residents with an increasing and emerging body of research suggesting microplastics can have a range of detrimental effects on human health.

The study, published in the journal Scientific Reports, was conducted by experts in marine science, human health, and big data from the University of Plymouth and Plymouth Marine Laboratory. It draws together existing research which has highlighted the presence of microplastics in sewage overspills, and the role of the wind in picking up and transporting sea spray and sea foam into the air and onto land.

With thousands of cities in the UK and worldwide still using combined sewer systems – comprising sewerage from treatment works and storm runoff – the research suggests coastal spills, when combined with onshore aerosolising winds, may serve as a “plausible and previously overlooked source of airborne microplastics.”

Dr Lauren Biermann, lecturer in marine science at the University of Plymouth and the study’s lead author, said: “Increasingly, I have been reading separate studies about incredibly high concentrations of microplastics and nanoplastics in sewage spills, how winds are stripping microplastics and nanoplastics from the ocean surface into the air, and the negative impacts of ingested or inhaled microplastics on human health. Our study is the first to make the connection between water pollution and air quality, and raises the question about potential health risks.”

Based on their theoretical findings, the research team has called for further investigation into any links between sewage spills, air quality, and any potential risks to human health.

Professor Clive Sabel, professor of big data and spatial science at the University of Plymouth and co-author on the study, said: “The health implications of this work are important. Inhaled microplastics can cross into our bloody streams and from there can accumulate in organs such as our brains and livers.

“We need legislation to force our UK water supply companies to remove microplastics from our waste water systems.”

The full study – The theoretical role of the wind in aerosolising microplastics and nanoplastics from coastal combined sewer overflows – is published in Scientific Reports.

Click here for more from the Oceanographic Newsroom.