Estimation of airborne viral emission: quanta emission rate of SARS-CoV-2 for infection risk assessment

Giorgio Buonanno; Luca Stabile; Lidia Morawska

CoronaVirus 2 (SARS-CoV-2 throughout this manuscript), emerged in Wuhan (China) in late 2019 122 and then spread rapidly in the world (https://www.who.int/emergencies/diseases/novel-123 coronavirus-2019). In Italy, an outbreak of SARS-CoV-2 infections was detected starting from 16 124 cases confirmed in Lombardy (a northern region of Italy) on 21 February. The Italian government 125 has issued government a decree dated 11 March 2020 concerning urgent measures to contain the 126 contagion throughout the country. This decree regulated the lockdown of the country to counteract 127 and contain the spread of the SARS-CoV-2 virus by suspending retail commercial activities, with the 128 exception of the sale of food and basic necessities. It represents the starting point of a system with 129 imposed constraints. Among the measures adopted for the containment of the virus in Italy, great 130 importance was placed on the safe distance of 1 m (also known as "droplet distance"). This distance 131 was actually indicated by the World Health Organization as sufficient to avoid transmission by air, 132