Pic-du-Midi observatory, French Pyrenees.

Scientists working 3000 metres above sea level have found a range of microplastics in air generally thought of a being “clean”.

Some of the samples of microplastic particles captured at the Pic du Midi Observatory in the Pyrenees, south-west France, are believed to have got there from the Atlantic Ocean.

The UK, North Africa, Canada and the US are also thought to be sources of the tiny particles, many of which were made of polyethylene, commonly found in plastic packaging.

According to researcher Steve Allen, some of the samples showed a marine source, coming out of the ocean and managing to get up into the free troposphere. “That basically completes the cycle of what we think plastics are doing,” he added, “it doesn’t stop anywhere, there’s never a sink, but a way station on to somewhere else.”

Those of us hoping to escape to the mountains for some fresh air might be concerned that most of the particles found were between 5 and 20 micrometres in diameter – which is apparently just the size to make us cough and give us asthma!

The research is published in Nature: Evidence of free tropospheric and long-range transport of microplastic at Pic du Midi Observatory, with summaries in New Scientist, Microplastics in French mountain air may have crossed Atlantic Ocean, and in The Guardian, No mountain high enough: study finds plastic in ‘clean’ air.