Despite the uncertainty that still exists in some of the scientific studies published to date, all seem to agree that The main way COVID-19 is transmitted is through the air. and that the risk of contagion in indoor environments is greater than that which may exist outdoors. In an indoor space, particles likely to contain viruses remain suspended in the air (aerosols) where, in the absence of ventilation, they accumulate.
In the following video, you can see a computational fluid dynamics (CFD) study carried out by Aalto University, Finnish Meteorological Institute, VTT Technical Research Centre of Finland y University of Helsinki where has the movement of particles released by a person sneezing inside a supermarket where the Air conditioning system.
One of the conclusions obtained is that the air currents produced by air conditioning and ventilation systems in enclosed public spaces will favour the rapid movement of this spray. If action is not taken on air conditioning systems, this could pose a high risk of contagion in the event of asymptomatic infected individuals.
Among the many installations, procedures and processes that SARS-CoV-2 forces us to review, all those that include air renewal or recycling play a relevant role.
It is for this reason that a Repurposing of air conditioning equipment it is going to play a crucial role in preventing the spread and contagion of SARS-CoV-2 in any facility in which they are used.
The particular case of the Terminal buildings at an airport, characterised by a high flow of people throughout the day, cannot be otherwise. Each terminal has a different air conditioning system, with some Specific temperature, humidity, and air change requirements. And it will have to be readjusted whether it is located in the Middle East, Latin America or Europe. What will have to be common and will be a priority in the operation of all of them will be:
- Maximise air renewals, diluting the contaminated aerosol inside the building, and avoid air recirculations. One and the same air conditioning unit can serve two distinct zones. If virus particles were present in one of them, the Recirculation carried out with the climate control equipment can transfer infected air to another area that shares air conditioning equipment.
- Usually el 20% del aire impulsado a una estancia procede del exterior. The increase of that 20% of outside air to the maximum possible will depend mainly on the external climatic conditions, the air handling unit batteries, and the existing production equipment. We will find many cases where, with the available equipment, it is not possible to operate under the “100% outside air” premise, and there is no other choice but to recirculate air. It will then be necessary to implementation of an additional solution, which can range from the installation of HEPA filters to the incorporation of modules in distribution networks that use virus and pollutant destruction technologies.
- Finally, it will be fundamental to Continuous extraction of air in toilets so as to create a depression with respect to adjacent spaces and prevent faecal-oral transmission (recognised by the WHO in its technical report of 2 March 2020) through contaminated airflow from toilets to other rooms.
The Return to normal operations at airports this will involve changes and adaptations to the facilities and to the operational procedures in place prior to COVID-19. The reconfiguration of air conditioning systems must be one of them.