Microplastics are now in the air we breathe – can we stop them?

Movement of microplastics inside the human airways

According to the researchers, an average human might inhale 16.2 bits of microplastic every hour. So, the amount of microplastics we inhale in a week would be enough to make a plastic credit or debit card.

When they studied the movement of microplastic particles of different shapes in human lung models demonstrating both slow and fast breathing conditions, they noticed that once these particles entered the human body, they began accumulating in the nasal cavity or backside part of the throat or oropharynx. 

The air passage in these parts had an asymmetrical shape that prevented microplastics from flowing further. “The flow speed, particle inertia, and asymmetric anatomy influence the overall deposition and increase the deposition concentration in nasal cavities and the oropharynx area,” explained Islam.

They also found that large-size particles tend to deposit more in the airways than smaller ones. For instance, microplastic particles that were the largest, at 5.56 µm, were more likely to settle in the airways.

Another interesting finding was that the rate of microplastic depositions in the human body was low under fast-breathing conditions, and when the airflow slowed down in the airways, the deposition increased.

Understanding the flow of microplastic particles in the airways is important as it could allow scientists to develop effective drug-delivery systems to target these pollutants inside the human body.   

Threats from air-borne microplastic pollution

Microplastics in the air come from degrading plastic items and moving vehicle tires, both of which are composed of toxic chemicals that are injurious to human health. 

For instance, debris from petroleum-derived plastic products like PVC pipes and nylon cords may even contain cancer-causing chemical agents. Similarly, pollutants in the worn-out tire particles negatively affect soil, water, and air quality. 

A report from CNN reveals that microplastics from tires are one of the main causes of harmful PM 2.5 air pollution levels in various places worldwide. Breathing such polluted air increases the risk of asthma, stroke, bronchitis, and other heart and lung disorders in humans, eventually reducing their average lifespan. 

Only after understanding the flow of microplastics in the human body and their effect on different organs can we devise ways to deal with the problem. The current study represents an initial but significant step in that direction.

Highlighting its importance further, YuanTong Gu, one of the study authors, said, “This study emphasizes the need for greater awareness of the presence and potential health impacts of microplastics in the air we breathe."

The researchers plan to further study microplastic movement in more complex human lung models in the future.

The study was published in the journal Physics of Fluids.