The correlation between the summer season, air conditioning and the coronavirus is currently a hot topic. With summer just around the corner, many people have started to wonder how the use of air conditioning systems might affect the spread of Covid-19.
The most closely monitored locations are offices and other enclosed workplaces, where people spend the entire day in close contact with each other. Considering that a compromised air conditioning system is a risk factor in the potential spread of the virus, its importance should not be underestimated.
Regulations proposed by the Italian Institute of Health
A recent document drafted by the ISS presents some rules and good practice guidelines to help protect the summer season and air-conditioning systems against the coronavirus. The first point highlighted is air quality inside workplaces: enclosed environments, without an efficient, regular change of air, can be a fertile breeding ground for the virus.
Although it has been widely demonstrated that the coronavirus does not spread via the air (but only via direct person to person contact), diluting the air in a room by ensuring that the air is constantly replenished, is very important. It avoids the accumulation of harmful particles, such as the aerosols produced by infected individuals when they breathe, cough or sneeze.
The ISS suggests airing rooms naturally, by opening the windows several times a day. Alternatively, ventilation systems can be used to ‘clean’ the air inside enclosed spaces, replacing it with fresh air from outside.
Recycling air without suitable filters is to be avoided
In the hot summer months, air conditioning systems can spread the coronavirus. This problem derives from the absence of adequate filters capable of blocking the microscopic virus particles. In a domestic or office environment, the filters used are designed to block pollutant molecules of a certain size, but anything smaller can pass through freely.
Replacing the air with fresh air from outside is the best solution in this case too. The ISS suggests people eliminate the air recycling function and keep ventilation systems on constantly. If there are long breaks during the working day, such as at lunchtime, it is preferable to turn down the ventilation without switching it off completely.
In hospital environments (usually fitted with advanced air-conditioning systems, with filters designed to prevent the spread of pathogens), they advise that where possible, air should be replenished rather than recycled.
Setting air currents correctly
In some specific environmental conditions, it has been observed that Covid-19 is able to travel longer distances than those currently recommended in social distancing (set at one metre in the regulations). This capability is influenced by air currents, emanating from air conditioning systems.
In enclosed environments, it is essential to pay particular attention to this aspect. Although people may be far enough apart, there is a real risk that the pathogen could be carried on air currents flowing from high to low.
The Italian Institute of Health guidelines are clear on this matter: descending air currents must be avoided or the air should be directed towards people’s faces. This also applies to workplaces and domestic environments (where people tend to take liberties with the rules, in order to enjoy the pleasant sensation of cool air on the skin).
Another precaution to combat the risk of infection from coronavirus is to set air conditioners to provide the right level of air humidity: despite a lack of specific studies on this, experts agree that optimal air humidity levels in order to minimise the risks are around 50 to 70%.
Translated by Joanne Beckwith