A study published in the Physics of Fluids journal by the Indian Institute of Technology (IIT) Bombay has found that wearing a mask while coughing results in a cloud of droplets suspended in the air which is up to 23 times smaller than if a face mask is not worn.
Researchers Amit Agrawal and Rajneesh Bhardwaj discovered that the volume of a cough-cloud without a face mask was seven times larger compared to a surgical mask and 23 times larger compared with an N95 mask, the face coverings used to protect oneself from air pollution, designed to block the smallest of airborne particles.
Their study also found that the cough-cloud was present in the air for five to eight seconds, after which it starts dissipating, irrespective of the presence or absence of a mask.
The authors also said that the role of air released during coughing and sneezing, and its subsequent fusion with the ambient air is crucial in understanding the spread of the pandemic. Their analysis further suggests that the first five to eight seconds after the starting of the cough event are crucial for suspending the exhaled droplets in the air. It also says the infected air volume is around 23 times more than that ejected by coughing.
They say that the presence of a face mask drastically reduces this volume and consequently cuts down the risk of the infection to the other person present in the room significantly.
The study has also said that coughing into the elbow and use of a handkerchief are some of the actions which drastically cut the distance travelled by the cough cloud and can reduce the volume of the droplets released and therefore chances of dispersion of the virus.
Face masks have become the essential 2020 item recommended by the World Health Organisation to reduce the spread of the deadly coronavirus