We also eat and drink these particles because microplastics are now everywhere, including in our veins. They’re in our tea, water, and food, and they’re in the air. We cannot avoid them and we still do not understand their effects on health.

Microplastics are everywhere

These tiny particles are created as a result of the breakdown of all the plastic that surrounds us, from major industrial processes to consumer products. One of the most important sources of these microparticles is the fashion industry, which is making synthetic clothing increasingly cheap. While microplastics are certainly not instantly toxic, there are concerns about the long-term effects of these tiny pollutants, especially as they build up inside us. What’s more, plastic has the ability to attract potentially harmful companions, including antibiotic-resistant bacteria, viruses, and toxic molecules like flame retardants and phthalates.

Understanding exactly where these particles stick is an important step towards understanding what they do while inside each of us.

Raising concern about serious respiratory health hazards, microplastics were first detected deep within the human respiratory tract in 2022.
– Mohammad Islam, an engineer at Sydney University of Technology, explains the motivation behind his research.

Islam and colleagues from around the world used a computational fluid dynamics model to safely investigate how microplastics move through our upper airways under different respiratory conditions. This type of model has provided effective predictions for other particle shapes for decades.

The largest microplastics tested (5.56 micrometers) were found to tend to get stuck in the upper airways, most likely in the nasal cavity or at the back of the throat. The shape of the plastic powder also affects where it settles. The scientist explains that the complex and highly asymmetrical anatomical shape of the airway and the complex behavior of airflow in the nasal cavity and oropharynx cause microplastics to deviate from the flowline and settle in these areas. Flow velocity, particle inertia, and asymmetric anatomy affect total deposition and increase sediment concentration in the nasal cavity and oropharynx.

Now Mohammad Islam and his colleagues plan to model how these particles move through our lungs.