Decades of research have shown the importance to health and safety of ventilation in public spaces. We recognise the importance of all available barriers in the defence against airborne pathogens such as the SARS-COV-2 virus but our focus is on ventilation – the key, but often ignored defense against disease transmission. Proper ventilation ensures the circulation of clean air through an indoor space, thereby clearing out pollutants. Assessment includes measuring carbon dioxide concentrations in specific areas of occupied indoor spaces as it has been shown that the carbon dioxide levels are a good proxy for the levels of other possible contaminants in the air. GreenFlag certification is issued if ventilation controls are adequate.
Very few Covid-19 infections are linked to the fomite route (spread by contact). Aerosol transmission of Covid-19 is by far the most important route of transmission. Virus-laden aerosols infect susceptible contacts in close proximity where they are most concentrated- like smoke. Infection of individuals at a distance greater than 1-2m is also common in poorly ventilated spaces.