A joint project carried out by four Finnish research organisations has studied the transport and spread of coronavirus through the air. Preliminary results indicate that aerosol particles carrying the virus can remain in the air longer than was originally thought, so it is important to avoid busy public indoor spaces. This also reduces the risk of droplet infection, which remains the main path of transmission for coronavirus

Aalto University, Finnish Meteorological Institute, VTT Technical Research Centre of Finland and University of Helsinki have studied how extremely small airborne aerosol particles emitted from the respiratory tract when coughing, sneezing or even talking are transported in the air. Such particles can carry pathogens such as coronaviruses.

The researchers modelled a scenario where a person coughs in an aisle between shelves, like those found in grocery stores; and taking into consideration the ventilation. Aalto University, VTT Technical Research Centre of Finland and Finnish Meteorological Institute each carried out the modelling independently, using the same starting conditions.

The researchers obtained the same preliminary result: in the situation under investigation, the aerosol cloud spreads outside the immediate vicinity of the coughing person and dilutes in the process. However, this can take up to several minutes. ‘Someone infected by the coronavirus, can cough and walk away, but then leave behind extremely small aerosol particles carrying the coronavirus. These particles could then end up in the respiratory tract of others in the vicinity’, explains Aalto University Assistant Professor Ville Vuorinen.