'Holding breath for long may increase Covid infection risk'

Chennai: Researchers, at the Indian Institute of Technology (IIT) Madras, have found that the process of virus-laden droplets being transported into deep lung increases with decreasing breathing frequency.

The team modelled the breathing frequency in a laboratory and found that low breathing frequency increases the time of residence of the virus and therefore, it increases chances of deposition and consequently the infection. Also, the multi-scale lung structure has a significant effect on a person's susceptibility to Covid-19.

"Covid-19 has opened a gap in our understanding of deep pulmonological systemic diseases. Our study unravels the mystery behind how particles are transported and deposited in the deep lung," the researcher, Mahesh Panchagnula, Department of Applied Mechanics, IIT Madras, said in a statement on Monday.

"The study demonstrates the physical process by which aerosol particles are transported into the deep generations of the lung," Panchagnula added.

The research team worked to gain a deeper understanding of how the rate of flow of droplet laden with virus determines the deposition of the virus in the lungs.

In their research, the team reported that holding the breath and having low breathing rate can increase chances of virus deposition in the lungs.

Airborne infections such as Covid-19 spread immensely through sneezing and coughing as it instantly releases a lot of tiny droplets. The research team imitated the droplet dynamics in the lung by studying the movement of droplets in the small capillaries which were of a diameter similar to bronchioles.

They took water mixed with fluorescent particles and generated aerosols from this liquid using a nebulizer. These fluorescent aerosols were used to track the movement and deposition of particles in the capillaries.

The researchers studied the movement of the fluorescent aerosol particles in capillaries of size ranging from 0.3 to 2 millimetres which covers the range of bronchiole diameters.

They found that the deposition is inversely proportional to the aspect ratio of capillaries, which suggests that the droplets are likely to deposit in longer bronchioles.