How does Corona Spread? Research from Harvard, Nature and NHK

July 6, 2020 – 3 Min

May 2020

With lockdowns slowly starting to ease across the globe and businesses looking to reopen, the focus is on how to reduce the spread of the virus to keep customers and employees safe. But how does coronavirus spread?

The Center of Disease Control (CDC) outlines that the virus that causes COVID-19 is thought to spread mainly from person to person and mainly through respiratory droplets produced when an infected person coughs or sneezes. These droplets can land in the mouth or nose of people who are nearby or possibly be inhaled into the lungs.

Recent research from The Harvard Medical School, The World Economic Forum and Wuhan University shows that these respiratory droplets can also stay airborne for up to three hours, making it possible for the virus to spread through the air via aerosols.

At Rensair, we provide hospital grade air-purification in a portable format to remove viruses spreading in the air. Rensair has proven scientific effectiveness of removing over 99.97% of airborne bacteria & viruses.

The latest research from around the world investigating how coronavirus can spread through the air:


Nature Research:

Aerodynamic analysis of SARS-CoV-2 proposes ventilation as a means to control spread of the virus.

A study from the journal of Nature Research, highlights that the new coronavirus appears to linger in the air in crowded spaces and rooms that lack ventilation.

Ke Lan at Wuhan University in China and his colleagues tested the concentration of SARS-CoV-2 RNA in aerosols — fine airborne particles — at two hospitals treating people with COVID-19 (Y. Liu et al. Nature; 2020).

“People produce two types of droplets when they breathe, cough or talk. Larger ones drop to the ground before they evaporate, causing contamination mostly via the objects on which they settle. Smaller ones — those that make up aerosols — can hang in the air for hours.”

The team found higher levels of these small aerosols in common bathrooms and areas with multiple people passing through. Especially high concentrations were found in a room where medical staff would remove their protective equipment (PPE), suggesting that particles contaminating their gear becomes airborne again when masks, gowns and gloves are removed.

On the other end of the spectrum, the level in rooms that were well ventilated like the isolation wards and patient rooms was at undetectable low levels.

“The presence of airborne viral RNA suggests that SARS-CoV-2 has the potential to spread by way of aerosols” the researchers say. They suggest that measures such as routine disinfection and better ventilation could help to control the virus’s spread.



World Economic Forum:

Micro-droplets that remain in the air for 20 min can be a spread of corona-virus. recently published a Japanese experiment by NHK, that seeks to understand how easily coronavirus can spread.

NHK states “we have so far considered the two main infection routes to be 1) objects that have virus on them, 2) inhaling droplets emitted by sneezes or coughs – but some experts say there is possibly a third infection route: micro-droplets in the air that are transmitted by for instance conversation. The louder people speak, the more droplets are transmitted from their mouth and into the air”

They continue “It is this third infection route that will be the key to reduce the further spread” .

The concern is highest for rooms with no or low air flow. Opening a window helps, however NHK underlines the importance of being able to have two openings to generate sufficient airflow. Do this at least once an hour. That lowers the risk of infection considerably.

Where opening a window is not sufficient or even possible to generate a good air flow, effective air purification could be a solution.



Harvard Medical School:

Coronavirus could possibly be inhaled

“The coronavirus is thought to spread mainly from person to person. Droplets that are produced when an infected person coughs or sneezes may land in the mouths or noses of people who are nearby, or possibly be inhaled into their lungs.

A person infected with coronavirus — even one with no symptoms — may emit aerosols when they talk or breathe. Aerosols are infectious viral particles that can float or drift around in the air for up to three hours. Another person can breathe in these aerosols and become infected with the coronavirus. This is why everyone should cover their nose and mouth when they go out in public.”

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