One year experiment for open and safe schools


September 2021- The year of experimentation that saw the Metropolitan City of Milan and Nanohub join forces to ensure greater stability and security for education and training activities has come to an end.

International epidemiological studies highlight the close relationship between exposure to pollutants in confined environments and the occurrence of respiratory and allergic symptoms in childhood, leading to a significant impairment of students’ quality of life and school performance.

In the context of a health emergency caused by Covid 19, Metropolitan City of Milan in collaboration with Nanohub   has identified the Istituto Schiaparelli-Gramsci in Milan as a suitable location in terms of type and size to launch a one-year experimental process (starting in September 2020) aimed at evaluating the use of an innovative filtration system in order to improve the quality of air in confined spaces, particularly those used for teaching and offer greater health protection to students and teaching staff.

At the beginning of the 2020-2021 school year, 52 air treatment devices using the unique KtV filtration technology developed by NANOHUB were installed. The installed devices (model “Levante 250“) have a treatment capacity of 250 m3 of air per hour and are suitable for the size of a classroom. The devices have been used, during normal teaching activities in the presence of pupils and school staff with no air intake of dangerous substances.

The following are the data collected at the end of the experiment, measured with an air sampling (according to the UNICHIM analysis method no. 1962-2) in 7 classes of the Institute during the period of teaching in presence.

The parameters sampled were the total bacterial load at 22° (cd “psychrophilic” of environmental origin), the total bacterial load at 37°(cd “mesophilic” of human origin) and the total fungal load.

In 4 classes, sampling for COVID-19 RNA was also carried out with a result of complete absence.

In order to evaluate the results of the test, the tables and indices proposed by Dacarro and collaborators (2000) and also used by INAL in the document “Safety and Wellbeing in Schools” (2015) were used as parameters of comparison. (2015). 

The samplings show that the global contamination index detected (ICGM, which corresponds to the sum of the bacterial load at 22°, 36° and the fungal load) is, on average, 1/3 of the level already considered “very low“.

(1) psychrophilic bacterial load -(2) mesophilic bacterial load – (3) fungal load -(4) Overall contamination index – (5) Mesophilic bacteria contamination index – (a) empty classroom at the time of sampling

Compared to the INAL document cited above, which gives an average global contamination figure (ICGM) of between 700 and 900 CFU/m3, the figure recorded at the Schiapparelli Gramsci institute is much lower: 146 CFU/m3 (a reduction of over 80%).

It must therefore be concluded that the use of the devices has resulted in very good air quality from a microbiological point of view, thus also guaranteeing a significant reduction and containment of the risk of contamination for students, teachers and all staff attending school environments.

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