Abstract:

In recent months we have lived under constant citizen concern due to the COVID-19 pandemic in all areas of our society, including teaching at all levels, from kindergarten to university, and involving all its members: students, teachers, and administration staff.

Research in this regard has revealed that this virus is transmitted mainly through the air in the form of aerosols, making closed places with a high influx of people ideal places for the proliferation and spread of this disease. Consequently, it has been recommended by medical and research institutions to avoid these areas as much as possible. If it is not feasible, it is highly recommended to frequently ventilate them to avoid accumulating the virus in the air. This situation occurs in the classrooms of all the educational centers where many students and teachers spend several hours with the consequent risk of contagion and spread of the disease.

One of the possible solutions proposed to stop the rapid spread of the virus is its detection in the air; however, currently, there are no ways to control whether SARS-CoV-2 is in a given environment using sensors. This virus has a diameter of 60 to 140 nanometers. Although there are currently particle sensors capable of detecting these dimensions, they cannot distinguish them from other particles of similar size. It should be noted that, although there are several research projects to detect the presence of SARS-CoV-2 in the air and immediately, they are still in the development phase, and their production and implementation are not expected soon.

Nowadays, there is no viable way to carry out this detection, which implies that we cannot be sure whether there are traces of the virus in a classroom, in suspension, that can infect students or teachers. However, this detection is not the only means to reduce risk in classrooms. The recommendations to ventilate closed spaces are often due to students' and teachers' circulation inside them. Apart from these possible viral particles, it is generated a stuffy atmosphere that depends directly on the number of people who have been there and the time they have spent in a particular closed space. This atmosphere can be measured simply and cheaply in a closed room by means of Carbon Dioxide sensors.

These measurements would allow knowing when it is convenient to air a closed space in real-time, allowing monitoring of all areas of a building. Using WiFi communication technologies practically installed in all educational centers, an alert system can even be established that allows those in charge of the classrooms to determine when to air one area or another. This contribution presents an easily replicable and low-cost prototype that allows real-time monitoring of the CO2 concentration. Therefore, the potential viral load of closed spaces with WiFi connection and both telematic and visual alert systems that they provide to an educational center certain levels of security and trust for all members of the educational community.

Consequently, this contribution's target is obtaining conclusions about the ventilation in classrooms, considering different scenarios. Thereby, CO2 will be measured in several classrooms analyzing parameters such as ventilation capability, number of students, classroom area, and class duration.

Keywords:

Classroom ventilation, COVID-19 prevention, ventilation effectiveness, CO2 measurement, air quality.