Can N95 respirators be reused after disinfection? And for how many times?

Lei Liao; Wang Xiao; Mervin Zhao; Xuanze Yu; Haotian Wang; Qiqi Wang; Steven Chu; Yi Cui

While the exact mode SARS-CoV-2's viral transmission is not known, a primary mode in viruses such as SARS and influenza is known to be through short-range aerosols and droplets. 11 When a person infected with a virus breathes, speaks, sings, coughs, or sneezes micron sized aerosols containing the virus are released into the air. Data gathered from influenza patients suggest that these aerosols are typically fine (<5 μm) or coarse (>5 μm). [11] [12] [13] For coarse particles, they can settle due to gravity within an hour. Fine particles, especially smaller than 1 μm, can essentially stay nearly indefinitely in the air. Droplets, or particles >10 μm, settle rapidly and are not typically deposited in the respiratory tract through means of aerosol inhalation. Particles >5 μm typically will only reach the upper respiratory tract, and fine particles <5 μm are critically able to reach the lower respiratory tract, similar to harmful particulate matter pollution ( Figure 1 ). While coughing and sneezing do provide many aerosols, the size distribution and number of particles emitted during normal speech serve as a significant viral transmitter. 12 Singing has been found to be comparable to continuous coughing in the transmission of airborne pathogens, 14 which was demonstrated during a choir practice on March 10, 2020 in Washington State. Although the choir members did not touch each other or share music during the rehearsal, 45 out of the 60 members of the Skagit Valley Choir were diagnosed with the virus three weeks later, and two have deceased.