evidence: Investigation of actual exposure to facial sheet mask preceding its risk assessment [...] Wearing face masks is an important and widely applied public health measure to control the COVID-19 pandemic1. A recent study, testing several batches of face masks intended to be put on sale as personal protective equipment, showed that 70% of the examined face masks contained TiO2 in quantities ranging from 100 to 2000 mg kg−12. This suggests that TiO2 is commonly applied in textiles of face masks, as in a wide variety of other textiles, e.g. to improve stability to ultraviolet light, as white colorant or as a matting agent3,4. In addition, to introduce new solutions to the challenges associated with the COVID-19 pandemic, textile companies are incorporating specific nanofiber, nanocomposite and nanoparticle technology into face masks5,6. Nanofibers containing TiO2 nanoparticles have been produced to create antimicrobial filters7, also in combination with silver8 and graphene9. Coatings of TiO2 nanoparticles on cotton fabric were applied for enhanced self-cleaning and antibacterial properties10. [...] Chua, M. H. et al. Face masks in the new COVID-19 normal: Materials, testing, and perspectives. Research2020, 1–40 (2020).