Author: Ivana Rae Almora

Published on 18 April 2025 at the Chemosensors Journal, the SynAir-G study “Monitoring of Indoor Air Quality in a Classroom Combining a Low-Cost Sensor System and Machine Learning” sheds light on the effectiveness of low-cost sensor (LCS) technology for monitoring indoor air quality in educational environments. The study is the result of a three-week monitoring campaign carried out in a primary school classroom in Athens, Greece, using the ENSENSIA sensor system, developed by FORTH. It focuses on evaluating the performance, reliability, and consistency of these sensors in measuring pollutants such as PM₂_.₅, CO₂, CO, NO, NO₂, and O₃.

Monitoring indoor air quality in schools is vital, as children are among the most vulnerable populations to the effects of air pollution. However, traditional high-precision instruments, while accurate, are often too costly and complex to be deployed widely in schools. The ENSENSIA system represents a more practical alternative, offering an affordable and scalable solution that could significantly expand air quality monitoring coverage in classrooms.

The study assesses the variability and accuracy of different ENSENSIA systems placed within the same classroom, comparing their readings to those obtained from high-end reference instruments. It also examines the potential of machine learning (ML) calibration to improve sensor performance. Of the eleven ML algorithms tested, Support Vector Regression was found to be the most effective for calibrating CO, NO₂, and O₃ sensors, while the Elastic Net model was best suited for NO sensors. These calibration techniques significantly improved the inter-unit consistency of the sensors and reduced discrepancies in daily exposure estimates by up to 50%.

Beyond evaluating accuracy, the study investigates whether these sensors can reliably capture daily and hourly exposure to pollutants and detect significant pollution events—such as those caused by nearby traffic—inside the classroom. The findings highlight the potential for low-cost sensors to support real-time monitoring and data-driven interventions that improve indoor air quality and safeguard children’s health.

The study is expected to contribute valuable evidence to the broader goal of ensuring healthier learning environments and could support future EU-level recommendations for indoor air monitoring in schools.

Montpellier, 2025 – Five schools in Montpellier are now involved in a major study on indoor air quality and its impact on children’s health. As part of the SynAir-G project, funded by the Horizon Europe program, CM1 classes from Heidelberg, Pottier, Bert, Brel, and Curie schools are taking part in research conducted in collaboration with the allergology research team at the CHU of Montpellier.

Understanding Indoor Air and Its Impact on Children’s Health

The SynAir-G project aims to better understand the interactions between indoor air components and their effects on children’s health and well-being. Schools are a key focus of this study, as students spend a significant part of their day in the classroom.

In this context, researchers are analyzing pollution peaks and seasonal variations in exposure, using sensors installed in the classrooms of participating schools. Students complete lifestyle questionnaires, and urine analyses are offered to volunteers to assess the impact on health more precisely.

These initiatives aim to identify students who may be at risk of developing asthma or other respiratory disorders and to explore solutions for improving air quality, such as installing green walls that act as natural air purifiers.

A Forward-Looking Project for Healthier Schools

The results of this study will provide a better understanding of the factors influencing indoor air quality and help adapt practices in schools. In the long run, this research could lead to European-level recommendations to promote healthier school environments and reduce risks associated with exposure to certain pollutants.

With SynAir-G, Montpellier and its CHU are fully engaged in an international research effort dedicated to improving children’s health.

Europeans spend 90% of their time indoors, yet Indoor Air Quality (IAQ) remains largely overlooked in policy frameworks. The “Mind the Gap: Toward a Comprehensive European Union Act on Indoor Air Quality” webinar, co-organised by the SynAir-G and EDIAQI projects, brought together leading experts to discuss how science, policy, and industry can work together to create an EU-wide IAQ framework.

A Fragmented Policy Landscape

Francesca Brady (GO AQS) highlighted the lack of cohesion in IAQ regulation, contrasting it with the more structured approach to outdoor air quality. She called for open-access regulatory guidelines, allowing policymakers, industry, and researchers to collaborate more effectively in accelerating IAQ policy implementation. She also stressed the importance of equity in IAQ legislation, ensuring vulnerable populations—such as low-income tenants—are better protected.

Industry’s Role in IAQ Policy

Francesco Scuderi (Eurovent) demonstrated how industry collaboration with policymakers has been instrumental in revising the Energy Performance of Buildings Directive (EPBD). He emphasized that beyond lobbying efforts, public education on IAQ is key to ensuring broad support for stricter air quality regulations.

From Science to Policy: Overcoming Fragmentation

Panagiotis-Minos Chaslaridis (EFA, IDEAL Cluster) described the puzzling policy fragmentation surrounding IAQ. While IAQ regulations exist, they are scattered across various sectoral policies—with notably little recognition in health policy. He stressed the need to translate scientific research into actionable policies, addressing both technical and political barriers.

One major roadblock? The perception that IAQ is solely a national competence. Chaslaridis argued that, given the health burden of poor IAQ, it should be recognized as a public health issue requiring an EU-wide response. He advocated for a clear EU definition of IAQ, an essential first step toward a harmonized regulatory framework.

The Role of Research and Academia

Dr. Pasquale Avino (University of Molise, EDIAQI) reinforced the critical role of academia in developing IAQ measurement methods and guidelines. However, he emphasized that one of the biggest challenges is changing public perception—for too long, outdoor pollution has been seen as the primary concern, despite the fact that we spend most of our time indoors.

Academia can also facilitate stronger collaboration between researchers, policymakers, and industry to ensure that scientific advancements lead to practical IAQ solutions.

Prioritizing Vulnerable Groups

Both Brady and Chaslaridis stressed that IAQ policies must consider the needs of vulnerable populations—including low-income communities, children, and those with respiratory conditions. Chaslaridis highlighted the importance of involving these communities directly in policymaking, as their first hand experiences provide crucial insights into the human impact of poor IAQ.

Brady pointed to the EU Green Deal and Renovation Wave Strategy as potential frameworks to integrate IAQ measures. However, public awareness remains a significant challenge—GO AQS is working to bridge this gap by promoting science-based evidence and fostering public-private partnerships to drive research and policy.

The webinar reinforced the urgent need for an EU-wide IAQ framework that integrates science, policy, and industry collaboration. With momentum building, stakeholders must now push for a common definition, minimum standards, and stronger public engagement to ensure that clean indoor air is a right for all.