The predominant shapes were particles and fibers, with polypropylene being the most common polymer. No doubt these are almost entirely due to synthetic fibres

The predominant shapes were particles and fibers, with polypropylene being the most common polymer. No doubt these are almost entirely due to synthetic fibres in clothing and other textiles, which have been around for more than half a century now: https://en.wikipedia.org/wiki/Olefin_fiber https://en.wikipedia.org/wiki/Olefin_fiber Note that natural fibres aren't great either if you inhale enough of them: https://en.wikipedia.org/wiki/Byssinosis https://en.wikipedia.org/wiki/Byssinosis The amount of pseudoscience and illogicity around microplastics is staggering. Consider those advocating for banning traditional blown-film plastic bags and replacing them with ones which are woven or non-woven fibre... the majority of which will also be made from plastic, but will emit loose fibres far more easily. Go after the textile industry if you really want to reduce microplastics, as that's where the majority of them come from. Of course this is assuming there is any clear evidence of harm, which is far from conclusive.