PM10 Indoor/Outdoor Air Quality Relationship in School Buildings: A Case Study in Barreiro

This article analyses the relationship between PM10 concentrations inside and outside two schools in Barreiro, Portugal: Primary School No. 5 and D. Luís Mendonça Furtado Basic School. The main objective was to understand the impact of external and internal sources on indoor air quality (IAQ) in school environments. Monitoring campaigns were carried out in different indoor spaces, including classrooms, the gym, and the canteen, and the results were compared with PM10 levels outside the building. At Primary School No. 5, indoor PM10 concentrations were consistently higher than the outdoor values measured on Avenida do Bocage, with an average Indoor/Outdoor (I/O) ratio of 2.2, indicating a significant impact of indoor activities on particle levels. Similarly, at the D. Luís Mendonça Furtado Basic School, there was an increase in PM10 and PM2.5 concentrations during school hours, with the highest I/O ratio (3.04) recorded on school days. In the evenings and at weekends, when the spaces were unoccupied, particle concentrations dropped considerably, reaching an I/O ratio of 0.70. Said results suggest that indoor activities are a determining factor for particle levels in indoor air, emphasizing the need for ventilation and pollution control strategies in schools to protect the health of students and staff.