Plastic particles less than 5 mm in size, known as microplastics, are becoming increasingly prevalent in various ecosystems. These tiny pieces of plastic can be found in industrial effluents and are also formed from the degradation of larger plastic waste. Astonishingly, microplastics have been found in numerous organs of both humans and animals, including the lung, heart, blood, placenta, and feces. Furthermore, a staggering 10 million tons of microplastics end up in the ocean, are released into the atmosphere through ocean spray, and subsequently contaminate everything we consume. These findings bring attention to the fact that microplastics may have integrated themselves as an integral part of clouds, which has dire implications for our health and climate.
While extensive research has been conducted on the impact of microplastics in aquatic ecosystems, very few studies have examined their contribution to cloud formation and climate change as “airborne particles.” However, a recent study led by Hiroshi Okochi, a Professor at Waseda University, and his team of Japanese researchers, sheds light on the path and consequences of airborne microplastics (AMPs) in the biosphere. Their findings emphasize the adverse effects of AMPs on human health and climate, underscoring the urgent need to address the issue of “plastic air pollution.”
To investigate the behavior of microplastics in the troposphere and the atmospheric boundary layer, the research team collected cloud water samples from various altitudes, including the summit of Mt. Fuji, the southeastern foothills of Mt. Fuji (Tarobo), and the summit of Mt. Oyama. Advanced imaging techniques such as attenuated total reflection imaging and micro-Fourier transform infrared spectroscopy were used to analyze the physical and chemical properties of the microplastics present in the cloud water. The researchers identified nine different types of polymers and one type of rubber in the AMPs detected. Interestingly, the majority of the polypropylene found in the samples was degraded and contained carbonyl (C=O) and/or hydroxyl (OH) groups. The diameters of the AMPs ranged from 7.1 µm to 94.6 µm, with the smallest particles observed in the free troposphere. Additionally, the presence of hydrophilic (water-loving) polymers in the cloud water was significant, indicating their role as “cloud condensation nuclei.” These findings strongly support the notion that microplastics play a crucial role in cloud formation and potentially have far-reaching implications for the climate.
The accumulation of airborne microplastics in the atmosphere, particularly in polar regions, poses a significant threat to the ecological balance of our planet. This imbalance may result in severe biodiversity loss, which could have irreversible and detrimental consequences for the environment. It is essential to address the issue of AMPs promptly to mitigate the potential damage to our ecosystems and habitats.
Professor Okochi highlights an alarming aspect of airborne microplastics: their accelerated degradation in the upper atmosphere due to strong ultraviolet radiation. This degradation process releases greenhouse gases, ultimately contributing to global warming. The faster degradation of AMPs in the upper atmosphere compared to the ground further emphasizes the urgency of tackling plastic pollution in the air.
The findings of this study shed light on the detrimental impact of airborne microplastics on both human health and climate change. It is crucial that we acknowledge and address the problem of plastic air pollution sooner rather than later to avoid irreversible environmental damage. By taking proactive measures to reduce the release of microplastics into the atmosphere, we can work towards a healthier and more sustainable future.