Short-term Health Benefits of Using Fresh Air Filtration System in Classroom

A randomized crossover trial among 90 primary students in 3 classrooms in Shanghai, China will be performed. Three arms are going to be 1) fresh air filtration system, 2) fresh air system with no filtration and 3) natural ventilation. Each arm is going to be in use for five continuous weekdays followed by one week of wash-out. After one-week of wash out, a cross over change between 3 arms is going to be taked. Then the 2nd week of intervention is performed followed by the 2nd wash-out week. The same cross-over change between 3 arms is going to be repeated again until each classroom will be applied by all three arms of ventilation. A total of 5 weeks is required for the project. Children's biological samples including saliva, urine and skin samples will be collected as well as exhaled NO. A questionnaire on children's perception on air quality will be assessed as well.