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Natural ventilation has become one of the most effective and sustainable strategies to address COVID-19 in confined spaces. Air intake through windows and other openings improves the Indoor Air Quality (IAQ) of a classroom, decreases the likelihood of respiratory disease transmission with an adequate social distance of about 1.5 m and is affordable in terms of energy consumption. In this study, a comparison of CO2 concentration, wind speed, number of people, type of ventilation and window surfaces of a school in a Mediterranean climate is carried out for 4 different cases of opening. For this purpose, CO2 levels were measured in different classrooms with different window openings (33%, 67%, 81% and 100% respectively). In addition, three types of ventilation (cross ventilation, partial cross ventilation and multidirectional ventilation) were analyzed in a time period between February and March 2021. The results show an interaction between CO2 levels and the type of ventilation. Thus, the fact that the window surface is a critical factor in reducing CO2 concentrations was determined, considering that the distance between students was approximately 1.5 m. Therefore, the orientation of buildings towards the predominant wind direction and the Window to Floor Ratio (WFR) should be reconsidered in new constructions. [ABSTRACT FROM AUTHOR]

Child Development Centers aim to provide multidisciplinary care for the population of children, a sector particularly susceptible to respiratory diseases due to the presence of fungal microorganisms that are dispersed by air currents in the spaces where users are. Therefore, the objectives of this work were to evaluate the fungal concentration of the indoor air of the Child Development Center of the University of Sonora, identify the taxonomy of the isolates and describe the possible pathogenicity for human health. From May 2 to May 27, 89 samples were taken from 17 places where minors are present and from a control point. Static samplings were carried out at a height of one meter, using SAS SUPER 100 equipment and sedimentation on Petri dishes with Agar Sabouraud culture medium. By the imprint technique, 14 fungal genera were identified. Among the predominant ones are Cladosporium spp., Aspergillus spp. and Penicillium spp., with 31%, 26% and 16%, respectively. The highest fungal concentration detected was 53 CFU/m3, a value lower than considered dangerous due to indoor air pollution by various government institutions around the world. However, species of clinical interest of the genus Aspergillus were identified, with A. niger predominant in all the sites, followed by A. ochraceus, A. flavus, A. versicolor and A. fumigatus. [ABSTRACT FROM AUTHOR]