Research shows humans might inhale about 16.2 bits of microplastic every hour, which is equivalent to a credit card over an entire week. And these microplastics—tiny debris in the environment generated from the degradation of plastic products—usually contain toxic pollutants and chemicals.
As far as I can tell this is a fluid dynamics simulation that only says that microplastics if breathed in probably mainly catch in the noise and throat.
It seems to have very little else to offer.