Background and objective: Quarter of the world population estimated to be exposed air pollution, from these population children are considering to be at risk as they spent 90% of their time indoors and mostly in school. The school is an important place for child psychosocial development and mental health. School environment has a direct effect on both physical and mental health of student, many health issues are associated with indoor air pollution (IAP) and with poor ventilation of the building and humidity. In 2017 world health organization (WHO) report that respiratory infection like pneumonia attributed to IAP and outdoor air pollution (OIP) and second-hand smoking caused death of 570 000 children under 5 years, this study aims to assess IAQ in public preschool in Jeddah. Methodology: This is a cross sectional study conducted in Jeddah, the preschool was selected according to the geographical location of the ministry of education, four preschools were selected. We used the following devise to assess the IAQ: an air detector for Formaldehyde (HCHO), Volatile Organic Compound (VOC) and fine particulate dust matter measuring (PM2.5) and (PM10), a carbon dioxide (CO2) detector with temperature and humidity. Result: Most of IAQ measure fall within normal range of WHO guideline except for CO2, we recorded the highest reading in the preschool in the east region (1595.78± 393.900) ppm and lowest reading in the preschool in the north (1143.27± 356.559) ppm Conclusion: Inadequate ventilation for the classroom during lesson were the main finding, high number of students in small classroom, closing window and door during lesson were mainly the cause of the high CO2. Education for the preschool teacher in how to maintain good air quality inside classroom and how to maintain active air way exchange is recommended.
