A high percentage of schools buildings in Andalusia does not have the necessary mechanical ventilation equipment or filtration systems in place, so air has to be renewed by means of infiltrations or opening the windows. A recent University of Seville study has analysed the air tightness of classrooms in Andalusia and the evolution of CO2 levels during the school day, via in situ monitoring, which serves as an indicator to determine air quality.
To that end, different tests were carried out in 42 classrooms in 8 education centres, spread across the different climatic zones that are typical of Andalusia, and in two different time periods, winter and autumn/spring, in which pressurisation and depressurisation tests were carried out to obtain the n50 value (the estimated rate of air renewal per hour for a space with a internal and external pressure difference of 50 Pascals). In addition, air temperature, relative humidity and Co2concentration were recorded, in order to study the impact of opening the windows by different degrees. At the same time, 917 students (between the ages of 11 and 17) were questioned about possible symptoms and health effects.
As a result of the research, he average values of air renewal obtained with windows and doors closed were approximately 7 h?1 (average air tightness), while the average values for CO2 concentration was about 1900 ppm, with only 17% of the total case studies showing values less than the 1000 ppm recommended for healthy environments by the WHO. Also, it was concluded that 42% of the case studies showed concentrations higher than 2000 ppm with the windows closed. In addition, it was shown that there was a higher level of symptomology, or level of discomfort as perceived by the students, when the windows were open (33% of the case studies). In contrast, certain symptoms, such as itchy skin and nasal congestion, could be identified as occurring in the periods in which the windows were closed, as these appear when CO2 levels are higher.
"Both the symptoms and the elevated levels of CO2 found show the possible degradation of air quality in the classrooms of Andalusia", states the University of Seville researcher Miguel Ángel Campano, who adds, "It is necessary to install controlled mechanical ventilation systems, so that they meet the current new-building regulations as well as the environmental ergonomic norms developed in Europe. It seems opportune to have the ability to filter external contaminants and to be able to guarantee the minimum external renewal airflow, to achieve CO2 concentrations below 1000 ppm".
In the published study, data is collected from 8 different schools, of which 25% are from before 2008, the year in which the Regulation of Thermal Installations in Buildings (Reglamento de Instalaciones Térmicas de los Edificios - RITE 2007) came into force, which means they do not have to meet this regulation's requirements. Of the other 75% of centres, only one has the necessary mechanical ventilation equipment to comply with this regulation, although during the period of the tests, it was established that these "had never taken effect" (according to the information gathered).