The air inside a hospital ward, a classroom or an office is shaped by decisions engineers make: how a building is ventilated, how people move through it, how warm it is, and how it trades fresh air against the energy needed to provide it. Our research turns those decisions into evidence, so that buildings can protect the people inside them without costing the earth.

Indoor air sits at the centre of two of the defining challenges of our time. The COVID-19 pandemic made it impossible to ignore that respiratory infections spread through the air we share indoors. But airborne transmission did not begin, or end, with COVID. Tuberculosis, measles, influenza and healthcare-associated infections all travel through indoor air, and the buildings we occupy are our first line of defence.

At the same time, the drive to net zero is pushing buildings to become more airtight and energy-efficient, which can work directly against the ventilation that keeps air healthy. The central question of our field is how to resolve that tension: how to deliver air that is both safe to breathe and low in carbon. Answering it takes measurement most groups cannot make, modelling most groups cannot run, and a real partnership between building physics, microbiology and data science. That is what this group brings together.

Airborne infection and bioaerosols

We study how infectious particles are generated, carried on air currents and inhaled, and how ventilation, airflow and human behaviour change the risk. Our work underpins infection-prevention guidance for hospitals and has shaped national and international understanding of how respiratory disease spreads indoors.

Cath Noakes, Marco-Felipe King, Louise Fletcher and Waseem Hiwar lead work spanning airflow and infection risk, the microbiology of the built environment, and quantitative infection-risk modelling in real healthcare settings, including how patients, staff and surfaces exchange microorganisms across a working hospital ward.

Detecting and measuring bioaerosols

You cannot manage what you cannot measure, and airborne micro-organisms are notoriously hard to capture. Mark Tarn brings bioaerosol detection down to the single-particle scale, using microfluidics, lab-on-a-chip devices and ice-nucleation science drawn from atmospheric research. Combined with our chamber and laboratory measurements, this lets us characterise what is in the air across scales, from an individual droplet to a whole room.

Building physics, ventilation and net zero

Healthy air is delivered by the physics of the building around it. Simon Rees and Sally Shahzad lead research on building energy systems, ventilation, thermal comfort and the low-carbon technologies, from geothermal heating and cooling to advanced building simulation, that decide whether a healthy building can also be a sustainable one. This is where the tension between infection control and energy is actually engineered.

Air-quality monitoring and data science

Real buildings are not laboratories, and the air in them changes by the minute. Douglas Booker and Amirul Khan work on real-world air-quality monitoring and the data science that makes sense of it, deploying sensor networks and applying machine learning to turn noisy, continuous measurement into insight people can act on. Through the HESTIA network, this work reaches into the home, asking how the retrofit of UK housing for net zero can be delivered without harming the air people breathe indoors.

Increasingly, we do not just measure indoor air. We assimilate live measurements into physics-based models to reconstruct what the air is doing in real time. Marco-Felipe King develops real-time data assimilation and high-performance airflow simulation that fuse sensor data with computational fluid dynamics, recovering a physically meaningful picture of airflow and exposure in an occupied room, with quantified uncertainty. It is a step towards genuine digital twins of indoor spaces: models that learn from the buildings they represent. This work connects directly to the group's wider strength in data-driven and computational methods.

Our research is anchored by a purpose-built aerobiology chamber, a controlled room-scale environment equipped with a heated thermal manikin that reproduces the buoyant plume of a real human body, and a three-dimensional lattice of air-quality sensors that captures how aerosols disperse through the space. It lets us run repeatable, fully instrumented experiments on airflow, aerosol transport and ventilation that would be impossible in a live building, measuring what most groups can only simulate.

This is complemented by molecular and microbiological laboratories for identifying airborne micro-organisms, and by high-performance computing for large-scale airflow simulation.

[Confirm before publication: any claim that the chamber is unique or the only one of its kind in the UK, only if you can stand behind it.]

Our research has anchored some of the UK's most significant work on air and health. HECOIRA, an EPSRC Healthcare Impact Partnership led from Leeds with two NHS trusts and industry partners, developed new computational tools to assess, monitor and control hospital environments for infection control and patient wellbeing. During the pandemic, the group helped shape the national response through TRACK (Transport Risk Assessment for COVID Knowledge) and the PROTECT National Core Study on transmission and the built environment, work that fed directly into UK government and NHS guidance. Today, the HESTIA network is carrying this agenda into the home, building a health-equity-centred approach to low-carbon housing.

Much of this work sits within the Healthy Buildings Network, a cross-institution community that translates building-environment research into healthier spaces, and connects to the Leeds Institute for Fluid Dynamics (LIFD), a major cross-disciplinary hub for fluid dynamics research at Leeds.

This is one of the most active PhD areas in the group, spanning building physics, microbiology, fluid dynamics and data science. We welcome students from engineering, physical sciences, environmental science and, increasingly, data science. Our researchers help lead the Leeds Institute for Fluid Dynamics and contribute to the EPSRC Future Fluid Dynamics Centre for Doctoral Training, offering PhD projects that bridge airflow physics and data-driven methods.

PhD opportunities · Meet the team

If you design, operate or regulate buildings, or you want to understand the air inside them, we would like to hear from you.

Contact the group

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