Evaluation of hazardous substances emitted during mask use

This study evaluated the inhalation of mask-derived materials by simulating real breathing conditions and examined how the amount of inhaled materials varies with breathing flow rate and duration. Three types of non-certified reusable masks and two types of certified disposable masks were selected. For each mask, five different hazardous materials were captured and analyzed in three replicates with two breathing flow rates of 30 L/min and 85 L/min and two breathing time combinations of 15 min and 60 min. Nanoparticles and total volatile organic compounds (TVOC) were analyzed using a real-time instrument, volatile organic compounds (VOCs) and phthalates were analyzed using gas chromatography–mass spectrometry, and metal elements were analyzed using inductively coupled plasma-mass spectrometry. Inhaled nanoparticle number concentrations decreased when wearing the masks, with certified disposable masks showing higher nanoparticle filtration efficiency (>90 %) compared to non-certified reusable masks (<40 %). These results were consistent with NaCl filtration efficiency results and showed no trend with flow rate or breathing time. TVOC were detected at high concentrations at the start of breathing, with a minimum of approximately 400 ppb and a maximum of 4,000 ppb. No target VOCs or metal elements were detected, while trace amount of phthalates were detected in non-certified reusable masks. The results of this study suggest that while TVOCs exhibit momentarily high concentrations shortly after the onset of breathing, hazardous substances derived from masks are either not inhaled or are inhaled only in trace. To reduce high concentrations of TVOCs, it is recommended to open the mask storage bag and briefly expose the mask to air, allowing the concentration to diffuse before use.