Practical Indicators for Risk of Airborne Transmission in Shared Indoor Environments and Their Application to COVID-19 Outbreaks

Some infectious diseases, including COVID-19, can undergo airborne transmission. This may happen at close proximity, but as time indoors increases, infections can occur in shared room air despite distancing. We propose two indicators of infection risk for this situation, that is, relative risk parameter (Hr) and risk parameter (H). They combine the key factors that control airborne disease transmission indoors: virus-containing aerosol generation rate, breathing flow rate, masking and its quality, ventilation and aerosol-removal rates, number of occupants, and duration of exposure. COVID-19 outbreaks show a clear trend that is consistent with airborne infection and enable recommendations to minimize transmission risk. Transmission in typical prepandemic indoor spaces is highly sensitive to mitigation efforts. Previous outbreaks of measles, influenza, and tuberculosis were also assessed. Measles outbreaks occur at much lower risk parameter values than COVID-19, while tuberculosis outbreaks are observed at higher risk parameter values. Because both diseases are accepted as airborne, the fact that COVID-19 is less contagious than measles does not rule out airborne transmission. It is important that future outbreak reports include information on masking, ventilation and aerosol-removal rates, number of occupants, and duration of exposure, to investigate airborne transmission.

Fil: Peng, Z.. State University of Colorado at Boulder; Estados Unidos

Fil: Pineda Rojas, Andrea Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina

Fil: Kropff, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina

Fil: Bahnfleth, W.. University of Pennsylvania; Estados Unidos

Fil: Buonanno, G.. Universidad de Cassino y del Lazio Meridional (u. de C. y del L. Meridional); Italia

Fil: Dancer, S. J.. No especifíca;

Fil: Kurnitski, J.. Tallinna Tehnikaülikool; Estonia

Fil: Li, Y.. No especifíca;

Fil: Loomans, M. G. L. C.. No especifíca;

Fil: Marr, L. C.. No especifíca;

Fil: Morawska, L.. University of Queensland; Australia

Fil: Nazaroff, W.. University of California at Berkeley; Estados Unidos

Fil: Noakes, C.. University of Leeds; Reino Unido

Fil: Querol, X.. ;

Fil: Sekhar, C.. No especifíca;

Fil: Tellier, R.. Centre Universitaire de Santé Mcgill; Canadá

Fil: Greenhalgh, T.. University of Oxford; Reino Unido

Fil: Bourouiba, L.. Massachusetts Institute of Technology; Estados Unidos

Fil: Boerstra, A.. No especifíca;

Fil: Tang, J. W.. University of Leicester; Reino Unido

Fil: Miller, S. L.. State University of Colorado at Boulder; Estados Unidos

Fil: Jimenez, J. L.. State University of Colorado at Boulder; Estados Unidos