World Health Organisation SARS-COV-2 Risk Assessment
The World Health Organisation, WHO, recently, March 2024, published a comprehensive manual to help with the creation of a formal, robust, scientific risk assessment relating to the risk of inside space occupants getting infected. This is a detailed document but worth reading if you are legally responsible for health and safety within your organisation.
Just by way of highlight, the following is from the introduction to the concept of infection rates; note even at TWELVE air changes per hour the risk of infection is still 3%! At 3 air changes per hour it is 10% - in 15 minutes of exposure, so what on earth is it in a room with closed windows and no air filtration where people are together for hours.
“Based on this model, in situations of high quanta emission, assuming 5 quanta/minute and a minute volume of 6 litres/minute), in a room of around 85 cubic metres, the estimated probability of infection for a 15-minute exposure in a room with 3, 6 and 12 ACH would be 10%, 5% and 3% respectively”