Speaker
Description
Introduction:
Indoor air quality has public health implications because people spend approximately 90% of their time in these environments. This project aims to gather an interdisciplinary team focused on indoor air quality, involving health, microbiology, architecture, and environmental, mechanical, and electrical engineering researchers. In this case, the indoor environments being analyzed are primary school classrooms. To date, there have been no similar analyses at the national level in Uruguay.
Aim:
From the environmental engineering perspective, the following research question is proposed: Does urban pollution from particulate matter (PM10 and PM2,5) affect indoor air quality in classrooms? Notably, in Montevideo (the capital of Uruguay), these pollutants' daily air quality objectives were exceeded on some occasions during 2023.
Methodology:
During 2023 and 2024, air quality was monitored both outside and inside classrooms simultaneously at two naturally ventilated school buildings in Montevideo (two classrooms per school were considered, one on the ground floor and one on an upper floor). Precisely, PM1, PM2,5, and PM10 concentrations were measured outside the schools (using an Aeroqual AQM10 device), and NO2, PM10, PM2,5, and CO2 concentrations were measured inside the classrooms (using Aeroqual S500 PM and NO2 devices, and a Senseair Sunrise 006-0-0008 device for CO2 concentration monitoring). In total, 22 weeks of data were collected for school building A and 10 weeks for building B. NO2 concentration measurement inside classrooms helps infer whether outside air is penetrating the indoor spaces, as there are no internal sources of this pollutant.
The equipment used outside the buildings was calibrated with simultaneous gravimetric measurements. The indoor and outdoor particle sensors were then operated together, resulting in different correction curves for the indoor sensor based on the relative humidity (measured simultaneously). The NO2 concentration sensor was used with its factory calibration.
Based on the measurements, an exploratory analysis was carried out, including calculating daily cycles and Pearson, Spearman, and Kendall correlation coefficients using hourly averages of the analyzed variables.
Results:
The daily cycles reveal that NO2 concentrations greater than 0 µg/m³ were measured, indicating the penetration of outdoor air into the classrooms. On the other hand, indoor particle concentrations were usually higher than outdoor concentrations.
Therefore, it is suggested that indoor particle concentrations result from the influence of outdoor air entering the classrooms and indoor particle emission processes, such as the resuspension of particles deposited on the floor. The correlation analysis tends to confirm these statements. For example, positive correlation coefficients were obtained between indoor particles and CO2 concentrations, indicating that classroom ventilation improves indoor air quality. Additionally, for the ground floor classrooms, positive correlation coefficients between indoor and outdoor particle concentrations were obtained, possibly indicating the outdoor air influence on indoor air quality.
Conclusions:
This study is novel for Uruguay, presenting the first interdisciplinary analysis of indoor air quality conducted in the country. From an environmental engineering perspective, intensive monitoring of air quality parameters was carried out, providing information to begin understanding the processes that dominate the presence of particles inside school classrooms in Uruguay. This monitoring will continue in 2025, incorporating the analysis of official air quality records from the city monitoring network to evaluate their spatial coverage concerning the buildings under study.
