E: Sources & exposure E.1. Source control INDOOR AIR QUALITY IN PRIMARY SCHOOLS: PRELIMINARY RESULTS OF THE ARIA PROJECT João C. Rufo 1,* , Joana Madureira 1 , Inês Paciência 1 , Cristiana Pereira 2 , João P. Teixeira 2 , Klara Slezakova 3 , Maria C. Pereira 3 , Mariana Pinto 4 , André Moreira 4 , Eduardo O. Fernandes 1 1 INEGI - Institute of Science and Innovation in Mechanical Engineering and Industrial Management, Porto, Portugal 2 National Institute of Health, Porto, Portugal 3 Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering of University of Porto, Porto, Portugal 4 Faculty of Medicine of the University of Porto, Porto, Portugal * Corresponding email: jcrufo@gmail.com Keywords: Children; Indoor air quality; Schools. SUMMARY Children spend a large part of their time at school, which might be reflected as a long term exposure to indoor air pollutants, possibly having a considerable impact on their health with an increased risk for developing asthma and allergies. The indoor air quality parameters (IAQ) of 10 primary schools were measured, including total volatile organic compounds (TVOC), formaldehyde, acetaldehyde, O 3 , NO 2 , PM 10 , PM 2.5 , ultrafine particles (UFP), bacteria and fungi concentrations. In addition CO 2 , temperature, relative humidity (RH) levels were also assessed. The indoor average concentration for the 10 schools is 251 ±141 μg/m 3 for TVOC; 18.1 ±7.1 and 7.8 ±2.4 μg/m 3 for formaldehyde and acetaldehyde, respectively; 6.5 ±11.6 μg/m 3 for O 3 ; 20.8 ±15.6 μg/m 3 for NO 2 ; 65 ±30 and 38 ±24 μg/m 3 for PM 10 and PM 2.5 , respectively; 9.06 ±4.6 x10 3 pt/cm 3 for UFP; 2246 ±1577 and 1164 ±2130 CFU/m 3 for bacteria and fungi, respectively; 1315 ±583 ppm for CO 2 ; 19.6 ±1.8 ºC for temperature; and 56.7 ±8.9 % for RH. The results indicate that children in primary schools are subjected to large concentrations of CO 2 and exposed to increased levels of particulate matter and biological contaminants. INTRODUCTION Children spend a large section of their time at school, which might be reflected as a long term exposure to indoor air pollutants. The levels and duration of the exposure to these pollutants might have a considerable impact on their health, with the possibility of developing diseases in the forthcoming years of their lives. For instance, certain non-communicable diseases, such as asthma and COPD, have been widely associated with poor indoor air quality (Jones, 1999, Geller et al., 2007, Baxi et al., 2013, Ferreira and Cardoso, 2014). Children are particularly vulnerable to air pollution due to their immature immune and respiratory systems, responding with lower effectiveness to environmental attacks. Moreover, the air volume that they