A team from the department of applied mechanics modelled the breathing frequency in a laboratory and found that the slower and deeper a person breathes, the greater the chance of the virus depositing deep in the lung.
When you breathe slower, the aerosol particles stay longer inside the lungs and the changes are greater that they will reach and deposit deep in the lung, said Prof Mahesh Panchagnula, who led the research team of Arnab Kumar Mallik and Soumalya Mukherjee.
“The morphometry and bronchioles of lungs as well as breathing pattern varies with individuals. So, it is hard to control that. But it affects the deposition rates,” he added.
Researchs globally found coronavirus spreads mostly through tiny droplets released when an infected person sneezes or coughs. The IITM team replicated the droplet dynamics in the lung by studying the movement of droplets in the small capillaries or blood vessels which were similar in size to bronchioles or air passages in the lungs.
For the study, they mixed fluorescent particles in water and generated aerosols from it using a nebulizer. The aerosols were then tracked for movement and deposition in the capillaries with a diameter of 0.3mm to 2mm.
The scientists found that when the aerosol movement is steady, the particles deposit in the lung by chance, but when movement is turbulent they deposit upon impact.
In an earlier work, the group also studied the variability in aerosol uptake from individual to individual, suggesting a reason why some people are more susceptible to airborne diseases than others. “The core motivation of this work is to understand why some people are more susceptible to airborne disease than others. There’s a biological immunity aspect to it but there is also a lung morphometry which could be different in some people, causing one person to be slightly more susceptible to infection than others,” Prof Panchagnula said.
“In some other related work, we found that the efficacy of wearing a mask is very good. If a Covid positive person wearing a mask coughs or sneezes, the aerosol production rate goes down by almost a factor of 1000. The mask also protects you from the large droplets produced when a person sneezes or coughs. It cuts both ways,” he said.