What you can’t see can still harm you: why hospital indoor air quality is vital
What you can’t see can still harm you: why hospital indoor air quality is vital
Hospital indoor air quality: healthcare’s invisible partner
No one has ever said they “enjoy” the smell of hospitals. In fact, for most people, it’s one of the more unusual and unsettling odours. But this isn’t because of the building or the cleaning products. It’s usually in the air itself: a cocktail of chemicals, particles and microbial traces that lingers in wards, corridors and waiting rooms. Patients dread it, visitors brace themselves for it, and staff… learn to endure it.
Indoor air quality (IAQ) influences how comfortable and safe people feel in hospitals. And while the smell is the most obvious thing that we notice, what matters most is what we can’t detect: the invisible pollutants, pathogens and imbalances that can have a significant impact on patient recovery and well-being, not to mention their safety. Across Europe and beyond, Equans works with hospitals to design, monitor and improve their air systems. Because we know that the quality of the air is as vital as medicine itself.
Why air matters more than walls
Hospitals are built to be visibly resilient, with solid walls, reliable equipment and carefully designed spaces. Yet what flows invisibly between those walls is just as important. The air is alive with microscopic elements, whether it’s volatile organic compounds (VOCs) from cleaning products, particulate matter from outside pollution or biological aerosols from people themselves.
For a patient with a compromised immune system, stray spores can mean serious complications. Meanwhile, for a surgeon, poor air quality can lead to increased fatigue and reduced focus. Even visitors waiting anxiously at a bedside feel the difference: a faint headache, a dry throat, a sense of unease in a stale room.
For many years now, the World Health Organization has considered air quality to be a key factor for health. But in hospitals, it is much more—it’s part of the clinical environment and as crucial as sterile instruments or trained staff.
Regulation and responsibility
Hospitals face rising expectations to monitor, report and improve indoor air quality. In the UK, the NHS Net Zero Building Standard ties clean air to environmental performance, urging hospitals to improve IAQ while cutting emissions. Meanwhile, in France, the BACS Decree mandates digital controls for large buildings, including healthcare facilities.
These frameworks further highlight a new reality. Air quality is not just a clinical measure but a symbol of accountability. It affects patient outcomes and staff conditions, and it is a significant factor for the hospital’s reputation and long-term sustainability.
From infection control to comfort
For many years, hospital IAQ was focused on infection control. This meant negative-pressure isolation, positive-pressure theatres and high-efficiency filtration, all of which are standard in operating rooms and ICUs. And all of these approaches still stand.
What has changed is that the brief has expanded. Now, ventilation must keep people safe and comfortable. This means:
- setting appropriate hourly air circulation for each room,
- maintaining temperature and humidity within comfortable ranges,
- tuning set points for each clinical use rather than a one-size-fits-all approach.
Relative humidity of 40–60% improves comfort and reduces the ability of viruses to survive in the air. Meanwhile, stable and clean ventilation lowers stress for patients and helps keep staff alert.
In short, IAQ isn’t just about avoiding harm; it improves well-being, resilience and trust.
Ventilation: the engineered backbone of clean air
Hospital heating, ventilation and air conditioning (HVAC) isn’t just “air in, air out”; it’s a carefully choreographed process. Air-change rates, filtration, pressurisation and zoning are all finely tailored to reduce clinical risk. Theatres and isolation rooms need strict pressure controls, whereas oncology suites need tighter particulate limits. And recovery areas require stable temperatures and humidity so that patients can rest. Connect this zone control to a smart building management system (BMS) and air quality becomes an active part of care.
Smart air: lessons from the digital hospital
In addition to these new standards, technology is changing the story. In emerging “digital hospitals”, air is continuously measured, analysed and adjusted. Sensors detect rising CO₂ in a crowded waiting area and trigger fresh air, and algorithms flag when components will need attention before they fail.
Furthermore, next-generation hospitals integrate smart air-handling systems that adapt in real time to occupancy and function. Combined with digital monitoring, these systems enable:
- early detection of air-quality fluctuations (e.g. humidity, CO₂ or particles)
- energy optimisation through demand-regulated ventilation that avoids over-ventilating empty spaces
- predictive maintenance for air-treatment systems (AHUs, filters, etc.)
In some hospitals, the same data can also be used to manage patient flows or prepare facilities for climate stress (e.g. during heatwaves or pollution alerts). As a result of all this, air becomes dynamic, adapting to conditions the way clinicians adapt to patients. Our teams are helping hospitals make this shift to connect IAQ with building management and clinical priorities in ways that are pragmatic, safe and transparent.
Charleroi: breathing room for recovery
Few projects capture this better than the Grand Hôpital de Charleroi in Belgium. Serving roughly half a million residents, the facility is among the most ambitious in Europe. From the start, air was treated as a design priority, not an afterthought.
More than 100 air-handling units supply a combined capacity of 1.2 million cubic metres per hour, feeding 23 operating theatres and 32 intensive care units. Each unit is monitored and adjusted digitally, creating a controlled yet flexible environment.
For patients, this translates into safety and comfort. For staff, it means assurance that their workplace is resilient. And for the hospital itself, it offers a model of sustainable infrastructure that treats hospital indoor air quality as an integral part of care.
Balancing clean air with climate goals
The clean air challenge is both medical and environmental. Ventilation and filtration consume energy and, if handled poorly, it can mean higher carbon emissions.
The solution lies in integration. Hospitals that connect IAQ systems with building management systems can reduce waste while maintaining clinical standards. Demand-controlled ventilation saves energy during low-occupancy periods, while heat recovery and renewable integration make clean air compatible with climate goals.
The healthiest hospitals in the future will be those that protect patients and the planet at the same time.
The way forward: air as care
Air isn’t just part of the environment; it is an unseen factor in every act of care. Breathing is the most constant (and most forgotten) act we perform; that is, until we find ourselves out of breath or have to hold it because of some horrible odour. The “hospital smell” may never go away completely and may always make us feel a little uneasy, but behind that familiar association lies a deeper truth: the quality of hospital air defines how we experience healthcare services. It influences patient recovery, protects staff, reassures visitors and is a sign of responsible management.
We believe air deserves the same attention as any other aspect of care. It is invisible but not neutral. Every hospital project is a chance to design an air system that heals as much as it protects. In the end, patient well-being isn’t just determined by the care they receive but the air they breathe every second of every day while they are being treated.
