EVAPORATION OF LEVITATED BACTERIA-LADEN DROPLETS AT DIFFERENT STAGES AND RELATIVE HUMIDITY*

A droplet is the main component of aerosols responsible for transmitting many respiratory diseases. Therefore, understanding the desiccation dynamics of the droplet in conjunction with infection studies is a comprehensive research study. Such studies are rarely attempted due to the complexity of experimenting with bacteria/viruses. Our study experimentally compared the levitated samples at two different relative humidity conditions and three stages of diameter-based evaporation. Our study demonstrates the role of the differential relative humidity-based precipitation in conferring virulence to infectious pathogens. For the same initial diameter of the droplet, the average mass evaporation rate for the droplet at low RH is one to two orders higher than the droplet at high RH conditions. Therefore, more evaporative stress is experienced by the bacteria in the low RH case. The bacterial survival is higher in the high RH case than in the low RH case. Also, the bacteria survive more at the early stage of the diameter-based evaporation than the final precipitate stage for both RH conditions. Therefore, the high RH samples exhibited increased virulence properties compared to the low RH samples.