The study population was composed by all the 71 nursery school teachers, employed at the town hall of Forlì, that worked in nine different school buildings similar in size and furniture. As provided for by the Italian law (Emilia-Romagna Regional Law No. 1 of January 10, 2000 - art. 32, followed by the Directive of July 25, 2001), teachers had the same working schedule and the same workload in terms of teacher/children ratio depending on children age.