

Uhm that doesnt work like that
Microplastics are mostly in water, and a huge issue there. They become small enough to get into cells and cause constant inflammation and cancer. But they are not aerosols.
Maybe very small plastic particles could get into air, but that usually happens when something burns. The most nasty microplastics occur when burning things.

I guess GIMP has worse auto-selection and general algorithmic things. But never tried PS