The persistence of plastic products in the environment has been studied widely in the last 50 years. Initially, all microplastics (MPs) were under the spotlight, however in the last 15 years, microplastic fibres (also known as microfibres) have attracted the attention of environmentalists, researchers and technologists, who began to realise the significant distribution of such polluting agents in several terrestrial and marine locations. In this series of reports, WTiN will attempt to clarify to what extent the current knowledge of microfibres emitted from fabrics can help to solve or limit the problem.

Here in Part I, a definition of primary and secondary microplastics, and a description of microplastic fibres from both natural and synthetic origins, are provided. Next, microfibres formation and shedding issues in the textile industry are explained as well as their provenance and their transport mechanism and distribution in terrestrial and marine environments.

In the upcoming Part II of this report, it was first important to clarify the distinction between bioplastics, biodegradable and compostable plastics before discussing to what extent natural and biodegradable fibres can be considered a possible solution to this problem. Moreover, the current testing standard methods to assess microfibre shedding during washing will be reviewed by describing the main research projects that have assessed shedding, also giving a glance to the tests under development. Finally, an outline of the short- and long-term adjustments that companies and consumers might put into practice to minimise microplastics will close the report.