The global COVID-19 and its variants put us on notice of the importance of studying the spread of respiratory diseases. The most common means of propagation was the emission of droplets due to different respiration activities. This study modeled by computational fluid dynamics (CFD) techniques a high risk scenario like a hospital elevator. The cabin was provided with an extraction fan and a rack for air renewal. Inside, a sneeze, a cough and a continuum speech were simulated. Inside the lift, two occupants were introduced to observe the risk of propagation of emitted droplets and the impact in diseases spreading risk. The fan effectivity over the droplets ejection was analyzed, as well as environmental condition of a clinical setting. For this purpose the amount of droplets inside were counted during whole time of simulations. The effect of the fan was concluded as able to eject the 60% of small droplets, but also a high performance in spreading particles inside. Among the three cases, the riskiest scenario was the continuum speech due to the saturation of droplets in airborne.

The impact of the COVID-19 pandemic has caused an increase in knowledge in certain fields such as human breathing and respiratory diseases. In the current study, enclosed-space characteristics were assessed due to the great debate generated because of the pandemic. Temperature, relative humidity, carbon dioxide (CO₂) concentration, particulate matter (PM) concentration and cumulative particle concentration percentage per size fraction were measured in three buildings under the occurrence of activities with different intensity levels. For the measurements, Arduino UNO, Sensiron SCD30 and APS-3321 devices were used. Natural ventilation was controlled via windows and/or doors, and the influence of air conditioning was studied in one of these rooms, in which medium- to high-intensity activities were conducted. All experiments revealed a decrease in temperature associated with an increase in the relative humidity when CO₂ decreased. As a consequence, drastic decreases occurred a few minutes after windows and doors were opened. In no-ventilation intervals, the observed linear increase changed into an asymptotic trend below the 1000 ppm limit recommended by Sinphonie guidelines. Additionally, the opposite behavior was observed between particles above and below a certain size. This experiment is of interest to further investigate critical ventilation rate versus volume of air per individual.