evidence: Most face masks don’t expose wearers to harmful levels of PFAS, study says "Per- and Polyfluoroalkyl Substances (PFAS) in Facemasks: Potential Source of Human Exposure to PFAS with Implications for Disposal to Landfills" [...] The researchers used mass spectrometry to measure nonvolatile and volatile PFAS in nine types of face masks: one surgical, one N95, six reusable cloth and a heat-resistant fabric mask advertised to firefighters. Surgical and N95 masks had the lowest levels, whereas the firefighting mask had the highest amount. Next, the team estimated the dose of PFAS that could cause health problems from chronic exposure, based on prior animal studies. According to the calculations, regular wear of the surgical, N95 and cloth masks would not pose a risk. However, the higher PFAS levels in the firefighter mask exceeded the dose considered safe, but only when worn for a full day (10 hours) at a high activity level, such as exercising or working in ways that boost the wearer’s respiration. Next, the researchers analyzed the environmental impact of PFAS from surgical and N95 masks (which comprise over 99% of masks discarded in landfills). They estimated that even if everyone in the U.S. over age 5 threw away one mask per day (90 billion masks per year), masks would be only a minor source of PFAS in landfill leachates and domestic water.