This paper investigates the size distribution of virus-laden droplets expelled from infected individuals, focusing on the implications for aerosol-mediated infection transmission in enclosed environments. The authors analyze the Poisson fluctuations in viral incorporation into droplets, demonstrating that for mild-to-moderate COVID-19 cases (viral loads < 2 × 10⁵ RNA copies/mL), droplets smaller than 20 µm at emission (10 µm after desiccation) are unlikely to be infectious. Cut-off diameters are presented as a function of viral load, revealing that median diameters of virus-laden droplets can be 1.5 to 20 times higher than the original droplets depending on the geometric standard deviation. The findings have implications for risk assessment, residence time estimation, and the evaluation of sanitization and infection control technologies.

S. Anand, Y. S. Mayya