Assessment of PM2.5 particulate matter exposure under different ventilation and air filtration strategies in a kindergarten

Many children between 1 and 3 years of age spend a fraction of their time in kindergartens. Poor indoor air quality, IAQ, could negatively affect children’s health, particularly respiratory health, attendance, and academic achievement. Children are at greater risk of getting severe health consequences from indoor air since their bodies are still developing, and children are more susceptible to the effects of air contaminants because they play closer to the ground, engage in more hand-to-mouth activities, and have a decreased ability to identify and protect themselves from potential threats. IAQ and exposure of children to PM_2.5 particulate matter in kindergarten depends on the strategy of ventilation and filtration used. In this paper, an assessment of PM_2.5 particulate matter exposure under different ventilation and filtration systems strategies in a kindergarten was performed. 
This study was carried out in a kindergarten for children aged 1-3 years located at Cordoba, Spain. A classroom of 114.87 m³ with 12 children and one teacher was chosen. PM_2.5 particulate matter values were measured in the breathing zone of children (0.65 m) under three scenarios: a) no ventilation system; b) mechanical ventilation system; c) portable air cleaner and d), a combination of mechanical ventilation and portable air cleaner. The measured data were analysed according to the type of activity performed by the children during the school day (9:05-13:30). The results showed that the intake mass was reduced indoor the classroom with the ventilation system (11%) when concentration of PM_2.5 particles outdoor was low. However, if concentration of PM_2.5 particles outdoor was high the intake mass was worsened by using the ventilation system (353%), by using the portable air cleaner (50%) and by a combination of both systems (144%). 
These results suggest that outdoor concentration has a high influence on indoor concentration. Therefore, to improve indoor air quality it is suggested the use of adequate air filters to avoid the ingress of outdoor contaminants to control the indoor PM_2.5 particles concentration.