Ventilation key to preventing Covid-19, say top UK experts

Check the ventilation in your office space because poor airflow raises the risk of exposure to Covid-19, top British experts advising the UK government on dealing with the coronavirus pandemic have said.

Experts on the Scientific Advisory Group for Emergencies (SAGE have called for making ventilation in public buildings and workplaces integral to policy measures, highlighting risk in poorly ventilated spaces. Measurements of elevated carbon dioxide levels in indoor air are an effective method of identifying poor ventilation in multi-occupant spaces.

Their advice is the second such conclusion after a University of Cambridge study in September found an increase in risk of exposure to the virus from ventilation systems in modern office buildings, which are designed to keep temperatures comfortable and increase energy efficiency.

The SAGE experts said in a paper released on Friday, “Ventilation is an important factor in mitigating against the risk of far-field (>2m aerosol transmission… Activities that may generate high levels of aerosol (singing, loud speech, aerobic activity are likely to pose the greatest risk; in some spaces even enhanced ventilation may not fully mitigate this risk.”

“It is more important to improve ventilation in multi-occupant spaces with very low ventilation rates… Virus survival in air decreases with increasing temperature and humidity. In most environments, this effect is likely to be less important than the ventilation rate. However, environments with low temperature and low humidity (for example, chilled food processing, cold stores may pose an enhanced risk,” they added.

The SAGE paper called for updated guidance on environmental control for Covid-19 across all sectors to provide explicit advice on the risk of far-field aerosol airborne transmission, the importance of ventilation, and recommendations on improving it.

“In the longer term consideration of infectious disease transmission needs to be embedded into building ventilation regulations and associated statutory guidance in the same way that energy, comfort and air quality have been incorporated,” the paper said.

The Cambridge study published in the Journal of Fluid Mechanics found that widely used “mixing ventilation” systems, which are designed to keep conditions uniform in all parts of the room, disperse airborne contaminants evenly throughout the space. These contaminants may include droplets and aerosols, potentially containing viruses.

The evidence, the study said, increasingly indicates that the virus is spread primarily through larger droplets and smaller aerosols, which are expelled when people cough, sneeze, laugh, talk or breathe.

Ventilation key to preventing Covid-19, say top UK experts