International. Health authorities have put in place the most severe restrictions on indoor spaces. Places such as bars or restaurants have suffered capacity limitations in the interior that have ranged from 100% to 50% in most cases.
For Carlos Martínez, technician specialized in indoor air quality at Sodeca IAQ, this makes us wonder: not only if this was the only option, but if these premises could operate at 100% of their capacity, with a reduced level of risk, if they adopted specific measures for the treatment of indoor air.
Martínez refers to the group of scientists from the University of Colorado, led by the Spanish professor José Luis Jiménez, who has developed a simulator [*] that allows to calculate the risk of contagion by aerosols inside buildings based on various factors such as capacity, ventilation or the use of masks: "The calculations extracted from these simulations cannot be considered exhaustive, due to the number of factors involved in the possibility of contagion, but they can help draw important conclusions if they are observed globally."
The IAQ technician illustrates it as follows (consult infographic): we can imagine a small restaurant of 50 m2, with a height of 2.7 m and a maximum capacity of 30 people, but which has been reduced by half (15 people) due to sanitary restrictions. The simulator allows us to configure a risk situation such that there is an infected person among the diners and that the only one who wears a mask uninterruptedly for a period of 2 hours is the waiter. In a room of these characteristics, with hardly any ventilation or air treatment system installed, the probability of contagion would be 38% according to the model.
However, the model tells us that if in this same situation, the premises were equipped with an air treatment system (including portable purifiers), which would allow ventilating and / or disinfecting the air until reaching a total of 6 renewals per hour of indoor air, the probability of contagion would be reduced to 11%. In addition, with this configuration, the premises could operate with a full capacity (30 people) and the probability of contagion would remain substantially lower (21%).
The analysis of the data obtained makes it clear that ventilation and indoor air treatment are much more important parameters to prevent the transmission of bioaerosols than the number of people present in an indoor space.
The first of the scenarios, despite being the most dangerous, is the only one that is currently regulated by current regulations. "It seems clear that society must bet on technological solutions for the treatment of indoor air that help improve their health and daily life. At the same time, this commitment must be encouraged by the competent authorities, through the application of laws that allow us to continue with our daily activity and, at the same time, protect our health."
