COVID-19: An Aerosol’s Point of View from Expiration to Transmission to Viral-mechanism

INTRODUCTION Coronavirus disease 2019 (COVID-19) emerged in Wuhan, China in late 2019, and soon unfolded as a global outbreak accompanied by declarations of a public health emergency of international concern (PHEIC) and later a pandemic from the World Health Organization (WHO). COVID-19 has resulted in 2,626,321 confirmed cases and 181,938 reported deaths worldwide (as of 14 April 2020). The underlying virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a highly contagious novel coronavirus that transmits as an aerosol and threatens people of all ages, from infant to geriatric, while those with cardiovascular disease are recognized as particularly susceptible to more severe symptoms from SARS-CoV-2 infection. WHO recommends using a mask to limit the COVID-19 outbreak; however, SARS-CoV-2 transmission models and its removal efficiency by wearing a mask remain unclear. Furthermore, differences in the field-specific definitions/terminologies related to transmission and mask usage tend to cause confusion and misunderstanding among both experts and the public.