New research shows that a combination of sewage overflows and coastal winds could be sending billions of airbourne microplastic particles into coastal towns and cities in Devon.

Scientists at the University of Plymouth examined two years of combined sewer overflow records alongside meteorological and satellite data to assess how often conditions for aerosolisation (the transfer of particles from water to air) occurred.

They 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 (23.4km/h) pushing back to shore and towards the city of Plymouth.

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.

Professor Clive Sabel, Professor of Big Data and Spatial Science, said: “The health implications of this work are important. Inhaled microplastics can cross into our blood 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 wastewater systems.”

The researchers say that with thousands of cities in the UK and worldwide still using combined sewer systems, comprising sewerage from treatment works and storm runoff, their findings suggest coastal spills – when combined with onshore aerosolising winds – may serve as a plausible and previously overlooked source of airborne microplastics.

Dr David Moffat, artificial intelligence and data scientist lead at Plymouth Marine Laboratory and co-author on the study, said: “There has always been a gap between the amount of microplastics we believed were being deposited in the oceans, and the concentrations that were observed by ship-based measurements. We think we have finally worked out why, and the impacts on human health are concerning.”

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.