New research from the University of Birmingham has demonstrated a new way of measuring and analysing indoor air pollution, revealing a clear relationship between office occupancy, physical activity and air quality.
In a pilot study conducted in central Birmingham, scientists combined radar-based movement detection with low-cost air pollution sensors to monitor how human activity influences indoor air quality in real time. The approach goes beyond simply counting occupants, instead measuring the kinetic energy generated as people move through office spaces.
The system was installed in both an open-plan office and a meeting room, where researchers tracked levels of PM₁₀, CO₂ and total volatile organic compounds (TVOCs) alongside patterns of occupancy and movement.
The findings showed that weekday PM₁₀ concentrations were up to four times higher during occupied periods than when the offices were empty. Average PM₁₀ levels during occupied periods reached 13.7 µg/m³, compared with 3.75 µg/m³ when unoccupied. The World Health Organization’s annual guideline for PM₁₀ is 15 µg/m³.
Other pollutants also rose significantly during working hours. CO₂ levels increased by an average of 130 parts per million to 584 ppm, while TVOCs rose by 318 µg/m³ to 495 µg/m³. Overall, CO₂ concentrations were 22% higher and TVOCs 140% higher on working days compared with unoccupied periods.
The researchers note that one of the most important contributors to indoor particulate pollution is resuspension caused by human movement, with particles trapped in carpets, furniture, office equipment, clothing and footwear being released back into the air.
The project was carried out in collaboration with Queen Mary University of London and sustainable engineering consultancy Cundall, bringing together expertise in air pollution science, radar-based sensing and indoor environment design.
Co-author Professor Francis Pope, Professor of Atmospheric Science at the University of Birmingham, said the approach responds directly to growing demand for practical solutions. ‘Government and industry are looking for evidence-based, low-cost methods to manage indoor pollution.
‘Our study creates a new way of analysing and discussing indoor air quality that can be used immediately to help create better buildings for work, leisure and living.’
Lead author Dimitrios Bousiotis added that measuring activity levels provides a more accurate picture of indoor air quality than headcounts alone: ‘Using the number of occupants alone to estimate indoor air quality is not as effective as considering the kinetic energy they generate. Our approach will help to understand better how the size, design, and use of different office environments impact air quality when workers operate within them.’
From an engineering and design perspective, the researchers say the findings could inform better ventilation strategies and building layouts in future office developments.
Jenny Carrington, from Cundall, said: ‘This new approach to analysing indoor air quality provides an affordable, easy-to-apply methodology that can help to better design cleaner and healthier indoor environments – improving people’s quality of life, as well as the occupational safety and productivity of workers in offices and other indoor workspaces.’
Dr Khalid Rajab, from Queen Mary University of London, highlighted the role of emerging sensing technologies in the study: ‘This study highlights the value of emerging sensing technologies – such as millimetre-wave radar – for assessing how human activities influence indoor air quality, and for helping to promote healthy living at home and in the office. This technology is particularly significant because it is unintrusive, uses no cameras or wearables, and preserves occupants’ privacy.’
The full research can be read here.
Photo: Alex Kotliarskyi / Unsplash
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