Respiratory Droplets Can Spread COVID 19 Faster: International Study

Published: July 21, 2020

As per the study conducted by a team of engineers from various countries, respiratory droplets from a cough or sneeze travel farther and also last longer in humid, cold climates rather than in hot and dry ones. The researchers came to this conclusion regarding the impact of environmental factors on droplets after devising a mathematical model that can be used to predict the early spread of respiratory viruses including COVID 19. This can also tell us about the role of the respiratory droplets in that spread.


The new model has been developed mainly to understand the role that droplet clouds play in the spread of respiratory viruses. It is the first such model based on a fundamental approach taken to study chemical reactions known as collision rate theory. This looks at the interaction and collision rates of a droplet cloud exhaled by an infected person with healthy people. This research connects population-scale human interaction with the micro-scale droplet physics results on how far and fast the droplets can spread and how long they last in the atmosphere.

The basic idea is that just like in a chemical reaction, two molecules will collide, here also the frequency of collision will determine how fast the reaction progresses.

It has been found that some respiratory droplets can travel between 8 feet and 13 feet away from their source before evaporating, based on the weather conditions, without even accounting for wind. This implies without masks, six feet of social distance may not be enough to keep one person’s exhaled particles from reaching another.

This research is expected to shape up public policy in various countries and can be used also to understand the role of the environment in the spread of a virus. The existing models use fitting parameters to apply data to an entire population but this model has changed that. Though there are certain limitations to this model, the team of researchers is working hard to make it more versatile and effective in the long run.