INFECTION CONTROL
Overcrowded hospitals: managing airborne risk
Corridor care is increasingly being used across the NHS as hospitals manage sustained capacity pressures, raising important questions about environmental and airborne infection risk in non-clinical spaces. Here, Barry Paterson, Chartered Engineer and founder of Germicidal UV Ltd (GUV), draws on ventilation standards, outbreak evidence, and practical healthcare experience to explore how clean air delivery and supplementary air cleaning can help mitigate shared air risk, and argues that airborne infection control in corridor care is not optional, but a systems-based environmental challenge that must be addressed alongside clinical practice.
Across the NHS, corridor care has become a visible consequence of sustained capacity pressures. Patients are increasingly treated in corridors, waiting areas and other non-clinical spaces when emergency departments and wards exceed capacity. The CQC has issued guidance to inspectors regarding care delivered in non-clinical spaces, reinforcing that corridor care must not become normalised and that trusts are expected to mitigate associated risks.¹ This creates a regulatory expectation: when non-standard spaces are used for care, environmental and infection risks must be assessed and managed. Infection prevention is often debated in binaries:
A precise zone of UVC irradiation just below the ceiling.
droplet or airborne, masks or ventilation, procedures or environment. The reality is far less dramatic, and far more practical. In healthcare, infection prevention works as a layered system: n Strong policies and training. n Disciplined clinical technique (hand hygiene, aseptic practice).
n Appropriate PPE. n Environmental controls like ventilation and air cleaning.
No single layer is enough on its own. Ventilation cannot compensate for poor procedural practice. PPE cannot fix weak environmental controls. Policies mean nothing without consistent application. Each layer reduces risk. Together, they create resilience. In my work, I
operate within the environmental layer, focusing on shared air risk. However, this approach is only effective when aligned with robust IPC practice across the board. Infection prevention is not about choosing one solution – it is about building systems where the layers reinforce each other.
60 Health Estate Journal September 2026
Airborne transmission and ventilation: what the evidence shows Respiratory infection transmission is influenced by multiple environmental and behavioural factors, including: n Ventilation rate. n Airflow patterns. n Occupancy density. n Duration of exposure.
The relationship between ventilation and infection probability is well established in airborne infection modelling, including the Wells–Riley equation.² The WHO recognises the importance of ventilation in reducing airborne transmission of respiratory pathogens and has issued technical guidance emphasising both air changes and air cleaning.3,4 The core principle is straightforward: increasing clean air delivery (through ventilation or air cleaning) reduces the concentration of infectious particles in shared air. Hospital ventilation systems are typically designed
around enclosed rooms and defined airflow pathways. Corridors operate differently. Research into airflow dynamics in healthcare
environments demonstrates that door opening and staff movement can drive air exchange between rooms and corridors, allowing air (and potentially contaminants) to move across boundaries.5 When corridors are used for patient care:
n Occupancy density increases. n Exposure duration increases. n Multiple aerosol sources may be present. n Air mixing between clinical and non-clinical zones increases.
Shared air exposure is recognised in infection control guidance. For example, CDC measles guidance defines exposure as being in the same airspace as an infectious individual, including for a defined period after that individual has left.6 This demonstrates that in certain infections, shared air alone can constitute meaningful exposure.
Evidence from high-density healthcare settings Outbreak investigations across multiple pathogens demonstrate that indoor crowding and ventilation influence transmission dynamics.
n Influenza Ventilation and crowding have been identified as
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