From Evangeliou et al. (2020), Atmospheric transport is a major pathway of microplastics to remote regions, page 3:
"Surface concentrations of tire wear particles (TWPs) range between a few ng.m−3 and 20 ng.m−3 for PM2.5 and up to 50 ng.m−3 for PM10 (Supplementary Movie 1). Brake wear particle (BWP) surface concentrations reach 50 ng.m−3 at maximum (Supplementary Movie 1). The highest concentrations were calculated for eastern USA, Europe and South-eastern Asia. All concentrations (TWPs 0.4 μg.m−3 for PM2.5, 1.8 μg.m−3 for PM10; BWPs 0.8 μg.m−3 for PM2.5, 1.4 μg.m−3 for PM10) were far below air quality limits for PM (annual mean 10 μg.m−3 for PM2.5, double for PM10) and lower than typical black carbon (BC) concentrations in remote regions."
https://www.eurekalert.org/pub_releases/2020-01/urai-bda0107...
[1] https://www.fhwa.dot.gov/reports/tswstudy/Vol3-Chapter5.pdf
"One is social distancing, which may have cut down on the amount of general infection from contact with others.
Another is less air pollution, from fewer cars being on the roads."
I'd love to see increased incentive for cities to act hastily on reducing <pm2.5 air pollution. Talk about a covert inequality exacerbator.