Effects of mouth coverings on co-occupant's exposure under different ventilation systems

Existed evidences show that the airborne transmission of human respiratory droplets may be related with the spread of some infectious disease, such as severe acute respiratory syndrome (SARS) and H1N1 pandemic. Ventilation system and personal protection are believed having certain positive effects on the reduction of co-occupant's inhalation, and have been investigated separately. This paper then aims to numerically study the performances of mouth coverings on co-occupant's exposure under mixing ventilation (MV), under-floor air distribution (UFAD) and displacement ventilation (DV) system, using drift-flux model. The size of investigated droplet residuals ranges from 1 μm to 10 μm since these droplets can reach the alveolar region and cause serious damages. The results show that using mouth covering can reduce the co-occupant's inhalation greatly by interrupting direct exposure to the expelled droplets, and best performance may be achieved under DV since the coughed air are mainly confined in the microenvironment of the infector.