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SARS-CoV-2 aerosol transmission and <br />mitigation by improved building ventilation <br />Richard A. Chamberlin, Ph. D. (Physics) <br />Louisville, CO 80027 <br />cham314@hotmail.com <br />8/26/2020 <br />The global economy is plunged into crisis because of our collective <br />failure to contain the spread of the new coronavirus, SARS-CoV-2 which <br />causes the disease Covid-19. Three possible SARS-CoV-2 transmission <br />pathways are generally present at the same time in the proximity of a <br />contagious individual: fomites; ballistic particles; and, aerosols [1]. Because <br />all three transmission pathways are present, it has been hard to quantify <br />their relative importance. Although the topic is under debate, some <br />researchers have recently suggested that the relative importance for <br />asymptomatic or pre -symptomatic individuals is [2, 3] : <br />• Transmission by fomites: 15% to 20% <br />9 Transmission by ballistic particles: 5% <br />. Transmission by aerosols: about 75%. <br />"Asymptomatic persons seem to account for approximately 40% to 45% of <br />SARS-CoV-2 infections, and they can transmit the virus to others for an <br />extended period, perhaps longer than 14 days" [4]. Transmission from <br />pre -symptomatic individuals can be substantial[5]. <br />SARS-CoV-2 aerosols transmitted up to 4.8 m are now proven to <br />contain viable virus[6]. The possible great significance of aerosols in <br />transmission strongly suggest that wearing masks effective at blocking small <br />particles (e.g. N95), and that knowing interior room ventilation compared <br />to room occupancy are very important to mitigating the spread of the virus. <br />In the United States, and in some other countries, mitigation strategies <br />such as mask wearing and social distancing are not sufficiently effective due <br />1 <br />