Contamination and airborne transmission of SARS-CoV-2

SARS-CoV-2 is a virus whose primary means of transmission has been demonstrated to be via the airborne route [Transmission of SARS-CoV-2: implications for infection prevention precautions]. In contrast to an initial belief that transmission without direct contact was considered to be due to contact with contaminated surfaces, the current consensus now accepts the hypothesis of distant transmission by aerosols as the most relevant. This fact should guide the principles of prevention and disinfection.
Initially, hygiene was mainly focused on cleaning surfaces, hand washing, and keeping distance. However, as the dynamics of contagion became clearer, it was realised that this virus remained in the air longer than previously thought and that it also travelled in aerosol form, and could spread further than initially thought. Thus, the air we breathe became the source of the problem, which forced us to improve the ventilation of spaces and the use of masks indoors, all of these measures aimed at reducing the viral load in the air we breathe.

Transmission route on a typical day; a) simplified diagram of aerosol and contact transmission; b-g drawings illustrating exposure to the virus in different environments [Reference]

Reducing the viral load in the enclosed spaces we share is therefore essential for coexistence and the recovery of the social habits we enjoyed before the pandemic. Opening windows and natural air circulation is the cheapest and most effective solution, but it is not always possible, either because of the climatic situation, the layout of the room, or the particular use of the building.

The use of air filters allows the air to be cleaned to a certain extent, but it is not feasible to filter out viruses of the size of SARS-CoV-2, so their use would help to eliminate droplets and other germs, but would not completely solve the problem.

Faced with this situation, the use of ultraviolet C (UVC) germicidal light as proposed in the COVILED project, a clean and non-polluting source of radiation, is presented as an innovative and differentiating element.

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