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Clean Air for Schools

Results after 4 years of the project

The Clean Air for Schools project stems from an initiative launched in 2020 by Airscan, in cooperation with Belfius. Its aim is to support Belgian schools in improving indoor air quality to protect children’s health and reduce the schools’ carbon footprint. Over three years, 72 schools were equipped and monitored to analyze three main types of pollutants: carbon dioxide (CO₂), fine particulate matter (PM2.5), and volatile organic compounds (VOCs).

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Context

Health issues and choice of pollutants to monitor

Monitoring indoor air quality in schools is essential because children, who are more vulnerable than adults, spend a large part of their day in classrooms. Poor air quality affects their respiratory health, concentration, and academic performance. The Clean Air for Schools project focused on three main pollutants: carbon dioxide, fine particulate matter, and volatile organic compounds.

According to official recommendations, the thresholds used are:

  • CO₂: 900 ppm (SPF Belgium)
  • PM2.5: 5 µg/m³ (WHO)
  • VOCs: 79.6 ppb or 300 μg/m³ (Superior Health Council)
How?

Project methodology

The project begins with the installation of three indoor sensors in different classrooms of each school. An initial assessment is carried out one month later to evaluate the air quality in these spaces.

A presentation is then prepared to inform management, teachers, and prevention committees, and to suggest areas for improvement. These can range from optimizing room ventilation to recommendations related to cleaning schedules and the choice of products used.

A final check is carried out after six months to verify the effectiveness of the measures implemented. The graphs on the left illustrate the percentage of schools that succeeded in reducing indoor air pollution concentrations at the end of the campaign.

CO₂

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PM2.5

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Percentage of schools that reduced concentrations between diagnosis and final consultation (in blue)

Results

Compare air quality to recommended thresholds

The graphs on the right illustrate that, in the majority of schools, the average concentrations observed after six months of the campaign remained below the recommended thresholds for carbon dioxide and volatile organic compounds.

More specifically, 67% of establishments comply with the limit values ​​for CO₂ and 55% for VOCs. However, regarding PM2.5 fine particles, only 16% of schools show average concentrations below the threshold of 5 µg/m³.

See Phase 1 Results

CO₂

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PM2.5

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VOS

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Percentage of schools with average concentrations below the thresholds for CO2, PM2.5 and VOCs

Observation and results

Limitations of natural ventilation

Natural ventilation is not always sufficient, particularly in older buildings with few windows or in small, crowded classrooms, and it can introduce external particles. Mechanical ventilation offers a significant improvement: reductions of approximately 46% in VOCs, 25% in particulate matter, and 19% in CO₂, observed in 72 schools.
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CO2
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PM 2.5
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VOS

Average concentrations of the three pollutants measured in the 72 schools.

Clean Air for Schools is the result of a collaboration between Airscan and Belfius. The project, launched in 2020, aims to provide schools with the technological, human and financial resources to improve children’s health and reduce the climate impact of schools.

Recommendations

Solutions to improve air quality in classrooms

The proven effectiveness of ventilation systems

The installation of a ventilation system in a classroom has demonstrated spectacular results: a reduction in CO2 from 1,288 to 811 ppm, a 25% decrease in particulate matter and a 50% decrease in VOCs.

The importance of maintenance

Rigorous maintenance is essential. Clogged filters accumulate mold and debris, reducing efficiency and spreading contaminants. Proper design remains crucial for controlling humidity, temperature, and pollutants.

An affordable alternative: air purifiers

For those on a budget, air purifiers offer an effective solution against particulate matter. Successfully tested in a school to reduce PM2.5 levels in a room near the woodworking shop.

See Phase 2: Purify

Graph showing the percentage decrease in average concentrations in ventilated classrooms for the three pollutants compared to unventilated classrooms.

Recommendations

Conclusive results from the air purifier

The graph illustrates a dramatic reduction of over 50% in concentrations after the air purifier was installed. This case study highlights the crucial impact of school infrastructure on controlling indoor pollution: functional windows for natural ventilation, and extraction systems in workshops to prevent the spread of particles to other rooms.

Key lessons learned about school air quality

  • Particulate matter is the primary concern , more so than CO2 or VOCs.
  • Mechanical ventilation systems significantly improve air quality by reducing particles, CO2 and VOCs
  • Air purifiers offer proven effectiveness against particles, contributing to healthier indoor air.

Dit staafdiagram toont de fijnstofconcentraties voor en na de installatie van de luchtreiniger in een klaslokaal waar hoge concentraties werden gemeten.