Researchers have found tiny particles of plastic in clouds, where they may be contributing to climate change.
Scientists collected water from the clouds surrounding Japan's Mount Fuji and Mount Oyama at altitudes between 1,300-3,776m and then applied advanced imaging techniques to determine whether microplastics were present, reported Sky News.
Nine different types of polymers and one type of rubber were found in the airborne microplastics, at concentrations between 6.7-13.9 pieces per liter and sizes ranging between 7.1-94.6 micrometers.
They also found an abundance of hydrophilic (or water-loving) polymers, which they said might act as "cloud condensation nuclei" - suggesting they play a key role in rapid cloud formation, which might eventually affect the overall climate.
"Overall, our findings suggest that high-altitude microplastics could influence cloud formation and, in turn, might modify the climate," the scientists wrote in the study, published in the journal Environmental Chemical Letters.
"To the best of our knowledge, this study is the first to detect airborne microplastics in cloud water in both the free troposphere and atmospheric boundary layer."
The lead author of the research, Hiroshi Okochi of Waseda University, said: "Microplastics in the free troposphere are transported and contribute to global pollution. If the issue of 'plastic air pollution' is not addressed proactively, climate change and ecological risks may become a reality, causing irreversible and serious environmental damage in the future."
Airborne microplastics degrade much faster in the upper atmosphere due to strong ultraviolet radiation, Okochi added, which "releases greenhouse gases and contributes to global warming."
The researchers said this is the first report on airborne microplastics in cloud water.
In a statement about the study, Waseda University said research shows "microplastics are ingested or inhaled by humans and animals alike and have been detected in multiple organs such as lung, heart, blood, placenta, and feces".
"10 million tons of these plastic bits end up in the ocean, released with the ocean spray, and find their way into the atmosphere. This implies that microplastics may have become an essential component of clouds, contaminating nearly everything we eat and drink via plastic rainfall," it said.