Wearing time and respiratory volume affect the filtration efficiency of masks against aerosols at different sizes

• Published in: Environmental technology & innovation 2022-02, Vol.25, p.102165-102165, Article 102165
• Main Authors: Li, Xia, Ding, Pei, Deng, Fuchang, Mao, Yixin, Zhou, Lin, Ding, Cheng, Wang, Youbin, Luo, Yueyun, Zhou, Yakun, MacIntyre, C. Raina, Tang, Song, Xu, Dongqun, Shi, Xiaoming
• Format: Article
• Language: English
• Subjects: COVID-19; Face covering; Inward protection; Outward protection; Particle size distribution; SARS-CoV-2
• ISSN: 2352-1864; 2352-1864
• DOI: 10.1016/j.eti.2021.102165

Face masks are critical in preventing the spread of respiratory infections including coronavirus disease 2019 (COVID-19). Different types of masks have distinct filtration efficiencies (FEs) with differential costs and supplies. Here we reported the impact of breathing volume and wearing time on the inward and outward FEs of four different mask types (N95, surgical, single-use, and cloth masks) against various sizes of aerosols. Specifically, 1) Mask type was an important factor affecting the FEs. The FEs of N95 and surgical mask were better than those of single-use mask and cloth mask; 2) As particle size decreased, the FEs tended to reduce. The trend was significantly observed in FEs of aerosols with particle size 2 h under deep breathing (30 L/min); 4) Both inward and outward FEs of N95 and surgical masks were similar, while the outward FEs of single-use and cloth masks were higher than their inward FEs; 5) The FEs under deep breathing was significantly lower than normal breathing with aerosol particle size