How much ventilation is required to reduce transmission?
Although there is no “safe” ventilation rate to prevent the spread of pathogens altogether, ventilation that maintains lower CO2 levels (under 800ppm) is considered a lower risk environment. High CO2 levels (routinely above 1500ppm) are often a sign of poor ventilation and may create a higher risk environment.
Transmission models suggest that better ventilation can lower risks and reduce the probability of outbreaks Predictive and retrospective modelling of airborne infection risk using monitored carbon dioxide – Henry C. Burridge, Shiwei Fan, Roderic L. Jones, Catherine J. Noakes, P. F. Linden, 2022 (sagepub.com). However, ventilation is much more effective when it is used together with social distancing than when people are less than 1m apart.