In Europe, more than 64 million students and almost 4.5 million teachers spend many hours each school day inside pre-primary, primary and secondary schools (Eurostat). Children spend more time in school than in any other place except home. On average, children spend around 200 days in school per year and 70% of that time is spent inside classrooms. This correspond to almost 1 year inside a classroom throughout the primary school years. Therefore, the school environment need to be supportive, health-promoting, and conducive of the learning process. This means that schools should be clean, safe and comfortable with adequate lighting (daylight and electric lighting), indoor air temperature and relative humidity, adequately ventilated classrooms etc.
A growing number of children are “burdened with ailments that challenge their ability to be present and fully engaged at school” (Harvard, 2018). Asthma and allergy symptoms are associated with indoor air quality. Across Europe, the prevalence of children affected by asthma has become an increasing problem in the last few decades, and the frequency varies among the countries (less than 5% to over 20%).
In their 2015 review, researchers from Fraunhofer IBP write that ventilation rates should yield at least CO2-concentrations at a reasonable 1000 to 2000 ppm to achieve a hygienically unobtrusive indoor air quality. While levels below 1000 ppm are considered as hygienically unproblematic a level between 1000 – 1400 ppm is considered to be an appropriate hygienically level, whereas above and especially towards 2000 ppm, is becoming hygienically unacceptable for long exposures (Grün et al, 2015).
Studies of CO2-levels in classrooms in Europe and USA show that the average CO2-levels are between 1000 and 2000 ppm (Grün et al, 2015), (Fisk, 2017).
Several studies have shown that students perform better in school with improved Indoor Air Quality.
Grün et al (2015) cite 5 individual studies. They show that if airing strategies within schools are adopted properly to achieve a ventilation rate of 7.4 l/s per person, the overall performance, in the sense of speed, could be increased by 2.2% to 15%.