Ventilation key to preventing COVID-19 indoors, say aerosol specialists

As temperatures drop and many parts of the world head into autumn and winter, doors and windows everywhere are closing and with them a vital means of ventilation during the pandemic.

For anyone sharing a working space with other people, now is the time to consider investing in a ventilation system – or asking your boss to do so – as these are a more reliable and comfortable way of ensuring a steady supply of fresh air than opening a window.

A built-in mechanical air vent will continuously suck out old, humid air and replace it with fresh, oxygen-rich air with less humidity.

"Old air out, fresh air in," says Scheuch, a leading German specialist in aerosols. This also applies if you are sitting alone in a room, and customers or colleagues are only occasionally coming in.

Without ventilation, if you're infected, you will constantly be blowing the virus around and slowly filling up the room. "The visitor then breathes this in and can get infected."

In order to minimize any risk of infection, experts recommend maximizing the volume of air flowing from outdoors and reducing the amount of air being recirculated, as far as is possible. In addition, the ventilation system should run before and after space is being used.

If there's a chance people who are at-risk from COVID-19 might enter the space where others have been for a prolonged period, getting a professional ventilation system with a filter will be safer, say the U.S. Centers for Disease Control and Prevention (CDC), who suggest using portable high-efficiency particulate air (HEPA) system.

Scheuch also considers room air filters to be helpful. With the right equipment, you can filter out more than 90% of aerosols from the air in a room, he says.

It's important, however, that the devices can circulate the air volume of the room at least four times per hour. This means for a 50-cubic-meter (1,766-cubic-feet) room, an indoor air filter will need to have an airflow rate of at least 200 cubic meters per hour. Alternatively, you can have several units installed.

If you're sharing a space with other people and don't have access to a mechanical vent, then you should take care to regularly open windows and doors whenever possible. You should also avoid lengthy meetings in smaller rooms and Scheuch says you should consider splitting a 90-minute meeting into three 30-minute sessions.

Even with adequate ventilation, care must be taken to ensure that people in the closed room are kept at an adequate minimum distance.