AEROSOL MODE OF TRANSMISSION

AEROSOL MODE OF TRANSMISSION

Subject  : Science & tech

Context : This excessive high rate of transmission with increased disease severity means that the virus is more virulent, escaping immunity and spreading by other means than previously established mode such as droplets, urine or faecal matter.

Concept :

• This new mode could be ‘aerosols,’ tiny liquid particles from the respiratory tract generated when someone exhales, talks, or coughs.
• They can float in the air and can contain live viruses unlike droplets which do not float but settle down on ground or any surface in one-two minutes after exhalation.
• When inhaled, these aerosols make everyone vulnerable to viral infection.
• A scientific study recently published in ‘Lancet’ provides strong and consistence evidence that SARS-CoV-2 can remain in air for as long as for three hours with half-life of 1.1h., i.e. it will take at least 66 minutes for half of the virus to lose activity.
• Confirmed presence of the virus in air-filters and ducts in hospitals with Covid-19 patients also means that it predominantly transmits in the form of aerosol.
• The widespread presence of the virus and its ability to spread through aerosols suggest that a lockdown will have minimal to no impact on Covid-19 spread.

Aerosols

• Aerosols are defined as a combination of liquid or solid particles suspended in a gaseous or liquid environment.
• In the atmosphere, these particles are mainly situated in the low layers of the atmosphere (< 1.5 km) since aerosol sources are located on the terrestrial surface.
• However, certain aerosols can still be found in the stratosphere, especially volcanic aerosols ejected into the high altitude layers.