Environmental design for the nosocomial infection control in medical healthcare centres

Healthcare-associated infections (HAIs), also referred to as nosocomial infections, remain one of the most persistent and complex challenges confronting modern healthcare systems. Despite significant advances in clinical medicine, infection prevention protocols and pharmaceutical interventions, HAIs continue to contribute substantially to patient morbidity, mortality, prolonged hospital stays and escalating healthcare costs. The global experience of recent pandemics has further underscored the vulnerability of healthcare environments to infectious disease transmission and highlighted the urgent need for a more comprehensive, systems-oriented approach to infection control.

Within this broader context, the built environment of healthcare facilities has emerged as a critical, yet historically underemphasized, determinant of infection risk. Hospitals are not merely passive settings where care is delivered; they are dynamic, engineered ecosystems that actively shape interactions amongst patients, healthcare workers, visitors and microbial agents. Environmental control, encompassing the ventilation, airflow organization, thermal conditions, humidity regulation, spatial design and operational practices, plays a critical role in influencing pathogen transmission pathways. This special issue seeks to consolidate current knowledge and stimulate interdisciplinary dialogue on how environmental strategies can be optimized to reduce infection risks while maintaining functional, comfortable and sustainable healthcare spaces.

Reframing infection control from clinical measures to environmental systems

Traditional infection control paradigms have largely focused on clinical and behavioural interventions, including hand hygiene, sterilization procedures, antibiotic stewardship and the use of personal protective equipment. While these measures remain indispensable, they primarily address transmission at the point of contact rather than at the level of environmental mediation. Increasing evidence ¹ suggests that pathogens can persist and spread through multiple environmental routes, including airborne transmission, surface contamination and water systems.

The recognition of airborne transmission, particularly for respiratory pathogens, has catalysed a paradigm shift in how infection control is conceptualized. Rather than viewing air as a neutral medium, it is now understood as an active vector whose movement, dilution and filtration directly influence exposure risk. ² Consequently, environmental control must be integrated into the core framework of infection prevention, rather than being treated as a secondary or auxiliary consideration.

This shift calls for a systems-thinking approach, wherein the healthcare environment is analysed as a complex interplay of physical, biological and human factors. Such an approach necessitates collaboration across disciplines, including building engineering, architecture, microbiology, epidemiology and clinical medicine. ³ The contributions in this special issue reflect this interdisciplinary perspective, offering insights that bridge traditional disciplinary boundaries.

Ventilation and airflow organization

Ventilation in hospitals is widely regarded as one of the most effective engineering controls for reducing airborne infection risk. Conventional guideline ⁴ often emphasizes metrics such as air changes per hour, filtration efficiency and pressure differentials. While these parameters are important, they do not fully capture the complexity of airflow behaviour within occupied spaces.

Airflow organization, the spatial and temporal distribution of air movement, has emerged as a critical factor influencing pathogen transport. In healthcare environments, airflow patterns are shaped by a combination of mechanical ventilation systems, thermal plumes generated by occupants and equipment, and architectural features such as partitions and openings. These factors can interact in nonlinear ways, leading to unintended consequences such as recirculation zones, short-circuiting of supply air or cross-contamination between adjacent areas.

Operating rooms provide a salient example. Laminar airflow systems are designed to deliver clean air uniformly over the surgical field, thereby minimizing contamination. However, the presence of surgical staff, lighting equipment and heat-generating devices can disrupt the intended flow, creating turbulence and compromising performance. Similarly, in multi-bed wards, poorly designed ventilation systems may facilitate the spread of airborne pathogens from one patient to another, particularly in the absence of adequate physical barriers. ⁵

Recent research ⁶ in computational fluid dynamics (CFD) has enabled more detailed analysis of these phenomena, allowing researchers and designers to simulate airflow patterns under realistic conditions. It is a promising way to leverage CFD, alongside experimental measurements, to evaluate alternative ventilation strategies, including displacement ventilation, personalized ventilation and hybrid systems. These approaches aim to optimize not only air cleanliness but also airflow directionality and stability, thereby reducing the likelihood of pathogen transmission.

Personalized and adaptive ventilation strategies

One of the emerging themes in environmental control is the shift towards personalized and adaptive ventilation systems. Traditional ventilation approaches often assume homogeneous conditions within a space, delivering uniform airflow regardless of occupant distribution or activity. However, healthcare environments are inherently heterogeneous, ⁷ with varying levels of infection risk, occupancy density and thermal demand.

Personalized ventilation systems seek to deliver clean air directly to the breathing zone of individuals, thereby reducing exposure to contaminants in the ambient environment. In clinical settings, such systems may be particularly beneficial for protecting healthcare workers who are in close proximity to infectious patients. Similarly, localized exhaust systems can be used to capture contaminants at the source, preventing their dispersion into the broader environment.

Adaptive ventilation strategies, on the other hand, involve real-time adjustment of environmental parameters based on changing conditions. For example, ⁸ ventilation rates may be increased in response to higher occupancy levels or elevated concentrations of airborne particles. Advances in sensor technology and building automation systems have made it increasingly feasible to implement such dynamic control strategies. However, challenges remain in terms of system complexity, reliability and integration with existing infrastructure. ⁹

Thermal environment, humidity and human factors

The thermal environment is a multifaceted determinant of both pathogen behaviour and human susceptibility. Temperature and relative humidity influence viral viability, aerosol dynamics and host immune responses, creating a complex interplay that must be carefully managed in healthcare settings.

Low relative humidity, for instance, has been associated with increased survival of certain viruses in aerosols, as well as reduced effectiveness of mucosal barriers in the human respiratory tract. ¹⁰ Conversely, excessively high humidity can promote the growth of mould and other microorganisms, ¹¹ posing additional health risks. Maintaining an optimal humidity range is therefore essential, yet often challenging in practice, particularly in climates with extreme seasonal variations.

Thermal comfort considerations add another layer of complexity. ¹² Different groups within healthcare environments, including patients, surgeons, nurses and support staff, may have distinct thermal preferences and requirements. In operating rooms, for example, surgeons often prefer cooler conditions to mitigate heat stress under surgical attire, while patients may require warmer environments to prevent hypothermia. ¹³ These competing demands can create tensions between comfort and infection control objectives.

The concept of targeted or localized thermal environments has gained traction as a potential solution. By providing individualized thermal control, such as heated or cooled microenvironments, while maintaining overall environmental conditions that are less conducive to pathogen survival, it may be possible to reconcile these competing needs. Research in this area, including studies featured in this special issue, highlights the importance of integrating thermal comfort considerations into infection control strategies.

Surface contamination, materials and cleaning protocols

Although airborne transmission has received increased attention in recent years, surface-mediated transmission remains an important pathway for certain pathogens, particularly those that can survive for extended periods on inanimate surfaces. High-touch surfaces such as bed rails, door handles and medical equipment can serve as reservoirs for microbial contamination, facilitating indirect transmission via contact. ¹⁴

Material selection can have a significant role in influencing surface contamination. Certain materials, such as copper and its alloys, have intrinsic antimicrobial properties that can reduce microbial survival. ¹⁵ Advanced coatings and surface treatments are also being developed to enhance antimicrobial performance. However, the effectiveness of these materials in real-world settings depends on a range of factors, including wear and tear, cleaning frequency and interaction with disinfectants. ¹⁶

It is important to recognize that antimicrobial materials are not a substitute for rigorous cleaning and disinfection protocols. Instead, they should be viewed as complementary measures that can enhance overall infection control. The integration of material science, cleaning practices and human behaviour is therefore essential for minimizing surface-related transmission risks.

Spatial design, zoning and workflow optimization

Architectural design has a foundational role in shaping infection risk within healthcare environments. Spatial layout, zoning and circulation patterns could influence how people and pathogens move through a facility. ¹⁷ Effective design can facilitate separation of clean and contaminated areas, reduce crowding and support efficient workflows that minimize unnecessary contact.

Isolation rooms, particularly those with negative pressure, are a key design feature for containing airborne infections. However, their effectiveness depends not only on mechanical systems but also on proper use and maintenance. ¹⁸ Similarly, the design of waiting areas, corridors and nursing stations can impact the likelihood of cross-infection, particularly during periods of high occupancy.

Workflow optimization is closely linked to spatial design. By aligning physical layouts with clinical processes, it is possible to reduce the frequency and duration of contact between individuals, thereby lowering transmission risk. This requires close collaboration between architects, clinicians and facility managers, as well as consideration of human behaviour and organizational practices.

Digital technologies and smart healthcare environments

The rapid advancement of digital technologies offers new opportunities for enhancing environmental control in healthcare settings. Sensor networks can provide real-time data on parameters such as air quality, temperature, humidity and occupancy, enabling more responsive and adaptive control strategies. Integration with building management systems allows for automated adjustments to ventilation, lighting and other environmental variables.

Artificial intelligence and data analytics can further enhance these capabilities by identifying patterns, predicting risks and optimizing system performance. For example, machine learning algorithms may be used to predict periods of high infection risk based on historical data, enabling pre-emptive adjustments to environmental controls. ¹⁹

In addition, indoor positioning systems and wearable devices can provide insights into human movement and contact patterns within healthcare facilities. Such information can be invaluable for understanding transmission dynamics and evaluating the effectiveness of infection control measures. However, the implementation of these technologies raises important considerations related to data privacy, system interoperability and user acceptance. ²⁰

Balancing infection control with energy efficiency and sustainability

Healthcare facilities are amongst the most energy-intensive building types, owing to their continuous operation and stringent environmental requirements. Measures aimed at reducing infection risk, such as increased ventilation rates and high-efficiency filtration, can significantly increase energy consumption. This raises a tension between infection control and broader sustainability.

Addressing this challenge requires innovative approaches that balance these competing priorities. Energy-efficient ventilation systems, heat recovery technologies and demand-controlled strategies can help mitigate the energy impact of infection control measures. In addition, the integration of renewable energy sources and sustainable design principles can contribute to reducing the overall environmental footprint of healthcare facilities.

Life-cycle assessment and performance-based design approaches are particularly valuable in this context, as they enable evaluation of trade-offs between different design options. ²¹ The objective is to achieve solutions that are not only effective in reducing infection risk but also sustainable over the long term.

Future research directions

Several areas need further investigation. First, there is a need for more comprehensive and standardized metrics for assessing infection risk in relation to environmental parameters. Such metrics should capture the multidimensional nature of transmission pathways and enable meaningful comparison across studies.

Second, greater emphasis should be placed on real-world validation of proposed solutions. While modelling and laboratory studies provide valuable insights, field studies are essential for understanding how interventions perform under actual operating conditions.

Third, the integration of human factors into environmental control strategies remains an important area for development. Understanding how occupants interact with their environment, and how these interactions influence infection risk, can inform more effective and user-centred design solutions.

Finally, interdisciplinary collaboration will continue to be critical for advancing the field. Bridging the gap between research and actual practice requires engagement with a wide range of stakeholders, including engineers, architects, clinicians, policymakers and patients.

Concluding remarks

The prevention of nosocomial infections is a multifaceted challenge that demands a holistic and integrated approach. As this special issue demonstrates, environmental control is a central component of this effort, with the potential to significantly reduce infection risks while enhancing the overall quality of healthcare environments.

By advancing our understanding of how the built environment could influence pathogen transmission, and by developing innovative strategies for environmental control, we can move towards healthcare facilities that are safer, more resilient and better equipped to face the challenges of both current and future infectious disease threats.

It is our hope that this special issue will serve as a valuable resource for researchers, practitioners and policymakers, and that it will stimulate further innovation and collaboration in this vital area of study.