Microplastics have long been recognised as a significant environmental hazard. In a new study led by Professor Hiroshi Okochi, Japanese scientists identified microplastics in cloud water, primarily consisting of degraded polypropylene, which poses a threat to ecosystems and contributes to global warming. While the exact transport mechanisms and potential health risks of airborne microplastics in clouds are not fully understood, these findings may influence future climate projections.
Our environment, once a citadel of natural beauty and biodiversity, is now vulnerable. Pollution, habitat disruption, and the unsustainable use of resources are pushing the planet to the brink. This delicate balance within ecosystems is deteriorating, placing numerous species at risk.
The human population produces a staggering amount of solid waste each year. Within the extensive spectrum of waste products, single-use plastics notably exemplify our culture’s reliance on convenience and disposable habits.
Our daily lives are permeated with disposable plastics, from plastic utensils to water bottles, and their consequences are all too transparent. Their convenience is undeniable, but the real expense is often shrouded. The proliferation of single-use plastics has led to a pervasive and stubborn problem. These materials do not just disappear once we are done with them; instead, they prevail, causing environmental havoc and threatening ecosystems.
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What Are Microplastics?
In the 1970s, the scientific community was startled by the discovery of minuscule plastic fragments in the massive tract of the open ocean. It wasn’t until 2004 that the term “microplastics” found its way into scientific discourse, describing the persistent buildup of these tiny particles, mere microns in diameter, born from the unrelenting degradation of larger plastic items. This phenomenon had largely evaded study in the sector of plastic pollution concerns until recent years.
Microplastics are broadly categorised into two distinct sources: primary and secondary. The primary microplastics denote microplastics that intentionally infiltrate the environment at a miniature scale, measuring less than five millimeters in diameter. These microplastics are created through industrial processes like extrusion and grinding, serving as raw materials for producing various products, from cleaning agents to the notorious microbeads that have infamously permeated the cosmetics industry.
Secondary microplastics, on the other hand, are the offspring of larger plastic items gradually breaking down, be it the wear and tear of tire treads or the gradual shedding of minute particles from synthetic materials.
Even if we were to cease the release of larger plastic items into our environment today, the proliferation of microplastics is all but guaranteed. This is due to the ongoing fragmentation of the large plastic debris already present in our ecosystems.
Microplastics in Clouds
In a study led by Professor Hiroshi Okochi from Waseda University and published in September 2023, Japanese scientists delved into the trajectory of airborne microplastic particles (AMPs) within the environment to explore the involvement of minuscule plastic particles in the troposphere and the atmospheric boundary layer.
Researchers collected cloud water from different altitudes, including Mount Fuji (situated on Kengamine, the highest among Mount Fuji’s eight peaks) and Mount Oyama (located 50 km southwest of Tokyo), using advanced imaging methods to detect microplastics.
They identified various types of polymers in the AMPs, with degraded polypropylene showing a significant presence. The AMPs varied from 7.1 to 94.6 micrometres, with smaller particles found in the free troposphere. In every litre (0.26 gallon) of cloud water subjected to testing, plastic particles were discovered, ranging from 6.7 to 13.9 pieces. The cloud water also contained hydrophilic (water-attracting) polymers, suggesting that they were discarded as “cloud condensation nuclei.”
Polypropylene and polyethylene terephthalate were primarily detected at Mount Oyama and Tarobo in the atmospheric boundary layer. Other polymers were found at different locations. Mount Fuji had a more diverse range of polymer types, with polycarbonate being the major.
According to a 2019 report in the Marine Pollution Bulletin, polyethylene is the most common substance in the surface seawater of the Northwest Pacific Ocean. It has also been detected in cloud water from areas near the ocean surface, suggesting it might come from ocean-based microplastics. Despite the presence of oceanic air, the cloud water had a low sodium concentration, as sea salt particles tend to get washed away by precipitation.
Plastic pollution is a problem we often associate with our oceans and land, but now we are discovering that it extends to the air we breathe. The buildup of AMPs in atmospheric conditions, with a particular emphasis on their presence in polar regions, harms ecosystems. As they infiltrate the food chain, AMPs threaten the very fabric of these delicate environments. Okochi also stated that intense ultraviolet radiation in the upper atmosphere causes AMPs to break down more rapidly than on Earth’s surface, releasing greenhouse gases as they degrade, adding to the factors contributing to global warming.
However, it is still unclear and has not been extensively studied how these microplastics end up in so many different places, especially regarding the transport of microplastics through the air, as this is also the first report on airborne microplastics in cloud water.
Scientists are also uncertain about whether consuming microplastics is harmful to human or animal health and what specific risks they might pose. Despite these uncertainties, many countries are taking steps to reduce microplastics in our environment. In 2017, a United Nations resolution discussed the issue of microplastics and the need for rules to protect our oceans, their wildlife, and human health.
Okochi concluded that the findings conducted by the researchers can be used to “account for the effects of AMPs in future global warming projections.”
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