How can mechanical ventilation help reduce the risk of infection from viruses such as Covid?

Mechanical ventilation allows for a continuous and sufficient replacement of the air volumes in enclosed spaces through stale air extraction and fresh air intake. This helps to reduce the presence of viral bioaerosols that might otherwise remain suspended in the air and spread by air.

Enclosed and poorly ventilated spaces, especially if crowded, encourage the spread of airborne viruses (viral infections that are mainly transmitted by air, as in the case of SARS CoV-2). Covid spreads through particles emitted into the air during exhalation. Smaller particles (nebulised droplets, called aerosols) remain suspended in the air and can infect other people even at a distance. In a confined, poorly ventilated and humid environment the virus remains viable for longer and the infectious droplets produced by those who speak, cough or simply breathe can travel more than 10 metres. This is why, as recently confirmed by the World Health Organization (WHO), ventilation of enclosed spaces such as schools, offices and work spaces becomes a crucial factor in replacing air and diluting the presence of viral particles. While managing ventilation by simply opening a window is the most obvious and immediate method, it has several disadvantages. Properly sized mechanical ventilation automatically manages air replacement based on the needs of the spaces, without the need to open windows.