Abstract
Indoor air quality (IAQ) in schools is a major public-health concern, as pupils and staff spend extended periods in classrooms where air renewal, occupancy, and material emissions interact. A portable multi-detector was developed to monitor key indoor pollutants, namely carbon dioxide, particulate matter, total volatile organic compounds, and formaldehyde, using compact low-cost sensors integrated into an embedded acquisition system. The paper focuses on the description of the multi-detector and presents measurements obtained during a six-week campaign conducted in fourteen classrooms across five elementary schools under real operating conditions, with particular attention to formaldehyde data. Results show significant spatial and temporal variability of formaldehyde concentrations between classrooms, with median values ranging from 2 to 28 ppb. All measured concentrations remain below the WHO and ANSES short-term guideline (80 ppb), while only five classrooms exhibit median values below the French long-term guideline of 8 ppb. These findings highlight the relevance of multi-parameter monitoring for assessing exposure to indoor pollutants in school environments.
