Natural Ventilation Characterization in a Classroom under Different Scenarios

The COVID-19 pandemic has pointed to the need to increase our knowledge in fields related to human breathing. In the present study, temperature, relative humidity, carbon dioxide (CO₂) concentration, and median particle size diameter measurements were taken into account. These parameters were analyzed in a computer classroom with 15 subjects during a normal 90-minute class; all the subjects wore surgical masks. For measurements, Arduino YUN, Arduino UNO, and APS-3321 devices were used. Natural ventilation efficiency was checked in two different ventilation scenarios: only windows open and windows and doors open. The results show how ventilation affects the temperature, CO₂ concentration, and median particle diameter size parameters. By contrast, the relative humidity depends more on the outdoor meteorological conditions. Both ventilation scenarios tend to create the same room conditions in terms of temperature, humidity, CO₂ concentration, and particle size. Additionally, the evolution of CO₂ concentration as well as the particle size distribution along the time was studied. Finally, the particulate matter (PM_2.5) was investigated together with particle concentration. Both parameters showed a similar trend during the time of the experiments.