Researchers have identified the presence of microplastics in clouds over Mount Fuji and Mount Oyama, Japan. This discovery, published in Environmental Chemistry Letters, signifies the extent of microplastic pollution in the atmosphere and its consequences for the environment, agriculture, and human health.

Researchers collected air samples from various altitudes near Mount Fuji and Mount Oyama and discovered significant concentrations of microplastics in the clouds. The presence of these minuscule plastic particles at such heights suggests their widespread distribution in the Earth’s atmosphere.

Professor Hiroshi Okochi from Waseda University warns that plastic air pollution must be urgently addressed to prevent ecological and climatic repercussions.

Microplastics, defined as plastic particles smaller than five millimetres, are fragments resulting from the disintegration of larger plastic items, intentional additions to products, or industrial discharges. Common sources include tires and microbeads found in personal care products.

What is particularly concerning is the potential for plastic rainfall. Microplastics in clouds could descend to the ground during precipitation events and contaminate crops, water bodies, and ecosystems. This poses a threat to agricultural productivity and raises health concerns for humans who consume contaminated food and water.

The study suggests that the high concentration of microplastics found in the samples may contribute to cloud formation and aggravate greenhouse gas emissions, thus amplifying the impact of climate change.

Professor Okochi maintains that failing to address this issue proactively could result in irreversible environmental damage. He states, “We are at a critical juncture where the consequences of plastic pollution are not confined to land and oceans but extend into the very air we breathe. If we do not act swiftly, the ecological risks and climate change impacts could be catastrophic.”

Microplastics are also discovered in various parts of the human body, including the lungs, brains, hearts, blood, placentas, and even faeces. The full health impacts of microplastics are still under study. Research has already indicated issues such as behavioural changes in laboratory mice and links to conditions like cancer and irritable bowel syndrome.

The researchers from Waseda University collected air samples at altitudes ranging from 1,300 to 3,776 metres. These samples revealed the presence of nine different types of polymers, including polyurethane, and one type of rubber in the clouds. The cloud mist contained approximately 6.7 to 13.9 pieces of microplastics per litre.

Microplastics in the upper atmosphere are subject to degradation when exposed to ultraviolet (UV) light, a process that releases greenhouse gases.

The study also highlights the remarkable mobility of microplastics, demonstrating their ability to traverse long distances through the atmosphere and the environment.

Previous research has already documented the presence of microplastics in rain. Potential causes include sea spray or aerosols generated by crashing waves and bursting ocean bubbles, as well as dust particles from road traffic.