A new study has shown that clouds may have become contaminated with microplastics, resulting in plastic rainfall that contaminates food and water.
The study, published in the Environmental Chemistry Letters journal, sought to examine the presence of microplastics in cloud water and how this contributes to climate change.
Researchers from Waseda University in Japan collected water from Mount Fuji and Mount Oyama at altitudes between 1,300m and 3,776m and analysed the samples using imaging techniques to find out whether they contained microplastics.
According to the United Nations Environment Programme, microplastics are tiny plastic particles that are up to five millimetres in diameter. They say that in the last four decades, concentrations of these particles appear to have increased significantly in the surface waters of the ocean.
The researchers found between six and 12 pieces of microplastics per litre. These plastics also existed in nine types, but water-loving microplastics were abundant.
“To the best of our knowledge, this is the first report on airborne microplastics in cloud water,” said the authors.
The researchers also explained that the microplastics in the troposphere (the lowest region of the atmosphere, at a height of about six to10 kilometres) contribute to global pollution, and may worsen climate change and result in dire environmental damages in future.
Previous studies have confirmed the presence of microplastics on the land and in oceans, making this the first to establish presence of the pollutant in the clouds.
“Airborne microplastics are degraded much faster in the upper atmosphere than on the ground due to strong ultraviolet radiation, and this degradation releases greenhouse gases and contributes to global warming,” said Prof Hiroshi Okochi.
According to the National Library of Medicine, microplastics in the air can result from various sources including “synthetic clothing, abrasion of synthetic textiles, incomplete incineration of plastic waste, municipal solid waste, dust storms, abrasion from synthetic rubber tires, scaffolding mesh on construction sites, and synthetic turf”.
It adds that the abundance of microplastics will vary from pace to place depending on the altitude, latitude, environmental conditions and seasons. More microplastics are likely to be found near the ground than at high altitudes because of gravity.
The dangers of microplastics are many, including its ability to affect the digestive, respiratory, endocrine, reproductive, and immune systems. They can irritate the gastrointestinal tract leading to inflammation, abdominal pain, bloating, and changes in bowel habits.
Despite the risks, the world is expected to produce 26 billion tonnes of plastic waste by 2050.
