A Birmingham-led team has shown how everyday movement in offices can stir up indoor air pollution — and how radar and low-cost sensors could help engineers design healthier buildings.
Every step, swivel and stretch you make at your desk could be reshaping the air you breathe.
A team led by University of Birmingham scientists has unveiled a new way to measure and analyze indoor air pollution that directly links office occupancy and physical activity with air quality. By tracking how people move through a space, the researchers say engineers and architects can design buildings that are not only more energy efficient, but also healthier to work in.
Indoor air pollution is a major public health concern because people spend up to 90% of their time inside, and pollutants can build up in homes, schools and offices. The World Health Organization estimates that of 9 million deaths attributed to air pollution each year, 3.2 million are tied to poor indoor air quality.
Yet one important source of indoor pollution often flies under the radar: tiny particles that get kicked up from carpets, furniture, office equipment and even clothing and shoes as people move around. These particles, known as particulate matter, can irritate the lungs in the short term and contribute to serious conditions such as heart disease, stroke and lung cancer over time.
To better understand that link between movement and pollution, the Birmingham team worked with researchers from Queen Mary University of London and engineers from Cundall, a global sustainable design consultancy. They installed a new monitoring system in an open-plan office and a meeting room in central Birmingham.
The setup combined radar-powered movement detectors with low-cost air pollution sensors. The radar devices counted how many people were present and measured the kinetic energy they generated as they walked, stood up, sat down and moved through the space. At the same time, the pollution sensors tracked levels of inhalable particulate matter known as PM10, as well as carbon dioxide and total volatile organic compounds, or TVOCs, a group of chemicals that can come from cleaning products, furnishings, printers and other office sources.
When the researchers compared working hours with times when the office was empty, the pattern was clear. Weekday concentrations of PM10 — particles about one-fifth the width of a human hair — were up to four times higher when the office was occupied than when it was not. On average, PM10 levels reached 13.7 micrograms per cubic meter during occupied periods, compared with 3.75 micrograms per cubic meter when the space was empty. For context, the World Health Organization’s annual guideline for PM10 is 15 micrograms per cubic meter.
Other pollutants rose as well when people were present. Carbon dioxide levels increased by 130 parts per million to 584 parts per million indoors, while TVOCs climbed by 318 micrograms per cubic meter to 495 micrograms per cubic meter on working days.
The findings, published in the journal npj Climate and Atmospheric Science, suggest that it is not just how many people are in a room that matters for air quality, but how actively they are moving.
Lead author Dimitrios Bousiotis, a research fellow in the School of Geography, Earth and Environmental Sciences at the University of Birmingham, noted that relying only on headcounts misses a key part of the picture.
“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,” he said in a news release.
By quantifying movement with radar, the team was able to show how bursts of activity — such as people arriving in the morning, gathering for meetings or moving around after lunch — can stir up particles that had settled on surfaces. Those particles can then stay suspended in the air, where they are more likely to be inhaled.
The researchers argue that this kind of detailed, real-time information could help building designers and facilities managers fine-tune ventilation systems, cleaning schedules and layouts. For example, ventilation could be increased during known high-activity periods, or materials that trap fewer particles could be chosen for high-traffic areas.
Co-author Francis Pope, a professor of atmospheric science at the University of Birmingham, explained that the work responds directly to what policymakers and companies are asking for.
“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,” he said in the news release.
Cost and practicality are central to the approach. The pollution sensors used in the study are relatively inexpensive, and the radar technology can monitor movement without cameras or wearable devices, which can raise privacy concerns in workplaces.
Co-author Khalid Rajab, a lecturer at Queen Mary University of London, who specializes in sensing technologies, emphasized that advantage.
“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,” he said.
For Cundall, which advises on sustainable building design around the world, the method offers a practical tool to bring air quality into everyday decision-making.
Jenny Carrington of Cundall noted that the approach is both accessible and impactful.
“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,” she said.
The study focused on a single office site, but the researchers say the framework can be adapted to many types of indoor environments, from classrooms and libraries to gyms and homes. Because the system is modular, it could be scaled up to monitor entire buildings or targeted to specific problem areas.
Looking ahead, the team envisions integrating movement-based air quality data into smart building systems. In that scenario, ventilation, filtration and even occupancy limits could adjust automatically in response to how people are actually using a space, rather than relying on fixed schedules or rough estimates.
As cities push for greener, more energy-efficient buildings, there is a risk that tighter, better-insulated structures could trap more pollutants indoors if ventilation is not carefully managed. The Birmingham-led work suggests that paying close attention to human movement — and the invisible clouds of particles it stirs up — could be key to balancing energy savings with the basic need for clean, healthy air.
Source: University of Birmingham