Abstract
A large number of infectious diseases are transmitted by respiratory droplets. How long these droplets persist in the air, how far they can travel, and how long the pathogens they might carry survive are all decisive factors for the spread of droplet-borne diseases. The subject is extremely multifaceted and its aspects range across different disciplines, yet most of them have only seldom been considered in the physics community. In this review, we discuss the physical principles that govern the fate of respiratory droplets and any viruses trapped inside them, with a focus on the role of relative humidity. Importantly, low relative humidity—as encountered, for instance, indoors during winter and inside aircraft—facilitates evaporation and keeps even initially large droplets suspended in air as aerosol for extended periods of time. What is more, relative humidity affects the stability of viruses in aerosol through several physical mechanisms such as efflorescence and inactivation at the air-water interface, whose role in virus inactivation nonetheless remains poorly understood. Elucidating the role of relative humidity in the droplet spread of disease would permit us to design preventive measures that could aid in reducing the chance of transmission, particularly in indoor environment.
Highlights
One of the prevalent ways in which numerous viruses, bacteria, and fungi spread among plants, animals, and humans is by droplets of various sizes [1,2,3]
We attempted to summarize and elucidate those known physical mechanisms of droplet and airborne transmission that are influenced by relative humidity (RH)
RH starts to play a role the moment respiratory droplets are exhaled into the air
Summary
One of the prevalent ways in which numerous viruses, bacteria, and fungi spread among plants, animals, and humans is by droplets of various sizes [1,2,3]. Humans produce respiratory droplets during talking, coughing, sneezing, and other similar activities [4,5,6,7,8] These droplets, which potentially contain pathogens, spread outside the human body in different ways, enabling the pathogens to find a new host [1,2,3, 9, 10]. A better understanding of the role of RH for virus viability in droplets helps us understand the droplet spread of infections and seasonality of some viruses but can guide our understanding of using humidity as a non-pharmaceutical intervention [39, 40]. This review aims to summarize those physical mechanisms of droplet and airborne transmission of disease in which RH plays a role. We look into virusladen droplets (Section 6) and the various factors that influence the survival of viruses in these droplets with respect to changes in RH
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
