Why don’t we just open the windows?

At the end of November 2021, an article appeared in the authoritative British medical journal The BMJ. The title is ‘why don’t we just open the windows’? Since the item underlines exactly what we’ve been pointing out since the start of the pandemic, we’ve used it as the basis for this blog. The original article with all references to the underlying studies can be downloaded here.

Air transfer
In more and more countries, people are finally beginning to realize that the transmission of SARS-CoV-2 is mainly through the air. Various model studies have mapped this out. In addition, there are various practical situations that confirm that the virus is mainly spread via small aerosol-shaped particles that end up in the respiratory tract.

Healthcare, schools and offices, among others, should have been encouraged from the very beginning of the pandemic to improve air quality. Unfortunately, many authorities have stopped this by not recognizing the airborne distribution route. What exactly is the cause of this?

Reasons why indoor air was not taken seriously
First, most pathogens are invisible; second, you don’t know the system has failed until there’s an outbreak; and finally, you cannot always pinpoint a specific cause, making it difficult to carry out the most appropriate intervention. Infection control relies on a package of measures, which are believed to cover most transmission routes. This explains the (misplaced) emphasis on large drops and surface risks, such as disinfecting shopping carts in the supermarket. Sky is literally fuzzy. It is now important for more and more authorities to recognize the important role of air in the transmission of infections.

High costs
Another reason air quality has been sidetracked is because of costs. Most buildings are not designed from an air quality point of view, while energy savings and thermal comfort are at the top of the list of requirements. Outdoor air generally differs from indoor air in temperature and humidity, and conditioning outdoor air requires a lot of energy. In addition, adapting existing systems is time-consuming and extremely expensive. In addition, ventilation systems are usually managed by building operators and owners, not necessarily by the potential tenants.

Disadvantages of natural ventilation
Natural ventilation, such as opening windows, raises discussion about the temperature, especially in the winter. In addition, it does not optimally influence the airflow and windows or doors cannot be opened everywhere due to safety aspects.

Existing ventilation standards do not meet
How far are we now with indoor air quality? Existing ventilation standards hardly take into account the risk of airborne infections, while it must be accepted that most people contract SARS-CoV-2 by breathing contaminated air. Opening windows is a start, but it is certainly not enough to minimize the spread of SARS-CoV-2 or other airborne viruses.

Air cleaning and ventilation go hand in hand
The role of air cleaning in minimizing contamination has been neglected for a long time. Fortunately, more and more countries like Belgium, Germany and some states in the USA believe that ventilation and air cleaning go hand in hand. Placing of certified, professional (mobile) air cleaners ensures that the air in an indoor space is completely purified several times per hour. Contamination such as viruses, but also bacteria and particulate matter are continuously filtered, which ensures a room with clean and safe air.