... In practice, the extrusion temperature is above the melting point or the glass transition temperature for crystalline or amorphous polymers, respectively. Thus, thermal degradation and formation of ultrafine particles (UFP; particle diameter of 100 nm or less) occur which are generally released indoors during a 3D printing process (Stephens et al., 2013;Kim et al., 2015;Deng et al., 2016;Yi et al., 2016;Azimi et al., 2016;McDonnell et al., 2016;Steinle, 2016;Mendes et al., 2017;Floyd et al., 2017;Kwon et al., 2017;Stabile et al., 2017;Vance et al., 2017;Zhang et al., 2017;Seeger et al., 2018;Gu et al., 2019;Poikkimäki et al., 2019;Beisser et al., 2020;Jeon et al., 2020;Katz et al., 2020;Secondo et al., 2020;Dunn et al., 2020;Sittichompoo et al., 2020;Alberts et al., 2021;Viitanen et al., 2021;Dobrzyńska et al., 2021;Chýlek et al., 2021;Bernatikova et al., 2021;Stefaniak et al., 2021;Manoj et al., 2021;Tang and Seeger, 2022;Romanowski et al., 2022;Saliakas et al., 2022). These findings raised the awareness, as UFP exposure has been reported to increase the risk of adverse health effects (Oberdörster et al., 1995(Oberdörster et al., , 2004(Oberdörster et al., , 2005Hong and Jee, 2020;Schraufnagel, 2020). ...