New research has looked into the typical airborne diffusion patterns of the coronavirus on exhaled particles. This reveals that the airborne likelihood of viruses being present in a given space is multi-factorial. This comes from the Universidade da Beira Interior, Covilha, Portugal and the Università di Messina, Messina Italy.
The factors that need to be considered include the relative dimension of the microdroplets expelled by a contagious person and the atmospheric temperature and humidity. In addition, the presence of atmospheric particulate and pollution need to be accounted for. Pollutants can act as an additional vehicle for transporting the virus.
With this latter point, models of pandemic diffusion demonstrate a correlation between air quality and atmospheric pollution, and concentrations of viral particles. It is of concern that the coronavirus – the SARS-CoV-2 – can be detected in the air and remain viable 3 hours after aerosolization.
It also stands that large droplets tend to settle quickly, and they do not undergo total evaporation. This means they produce a potential infection in a zone close to the infected person.
With small droplets, these move from the hot and humid environment of the respiratory system to the colder and less humid external environment. Here the droplets are subject to evaporation mechanisms. It is the environmental conditions and thermodynamics that shape the degree of risk.
What is of further concern is the indoor environment, especially with active ventilation systems. This is in relation to diffusion rate of emitted droplets, which may be favoured by the use of heating, ventilation, and air conditioning (HVAC) systems that recirculate the air rather than drawing air in from the outside.
This finding adds to the complications that need to be worked through in order to best understand the dynamics of the coronavirus, including diffusion and rates of infection. To understand this better, the researchers have shown how a greater understanding of heat and mass transfer can help to understand infection rates. In other words, understanding the thermodynamics of living systems.
Where building modifications are difficult, the study recommends purifying the air such as with ozone or ultraviolet light and stepping up room disinfection.
The study appears in the International Journal of Heat and Mass Transfer and the research paper is titled “Could thermodynamics and heat and mass transfer research produce a fundamental step advance toward and significant reduction of SARS-COV-2 spread?”
