Impact of air treatment on nosocomial infections in hospitals
Healthcare-associated infections are a major public health issue in hospital facilities. These are infections occurring during or following care which were neither present nor incubating at the beginning of it, resulting in extended hospital stays and an increased risk of morbidity. To this must be added a significant increase in care costs. In this context, control of the hospital environment is an essential lever for prevention. It is at this level that indoor air quality plays an important role in the management of infectious risk.
In certain controlled environment areas, such as operating theatres, intensive care units or protected haematology sectors, the control of airborne contamination constitutes an important element of risk management. In these environments, the control of airborne contamination is a structuring technical requirement. Air treatment contributes directly to this control by ensuring flow regulation, particle filtration and the maintenance of stable conditions. The objective is to control airborne contamination and limit the concentration of contaminants in areas where risk analysis requires it.
How can air contribute to the transmission of infections?
Airborne transmission constitutes one of the possible mechanisms for the spread of pathogens in a hospital environment. In a healthcare facility, the air can act as a vehicle for contamination. The control of airborne contamination aims in particular to monitor the particles and microorganisms present in the air of controlled environment zones. They may also settle on sensitive surfaces.
The conditions of ventilation, filtration and air diffusion contribute to the control of airborne contaminant concentrations. Insufficient air change rates or inadequate filtration promote the accumulation of contaminants in the environment.
Air handling systems thus contribute to the control of several parameters: particulate cleanliness, filtration, flow regimes, differential pressures and, depending on the requirements of the activity, temperature and humidity.
What role does air handling play in infection prevention?
Hospital air treatment systems are designed to ensure rigorous control of air quality. Their operation is based on four main complementary mechanisms.
- Filtration makes it possible to reduce the concentration of airborne particles, with levels of efficiency tailored to the desired performance.
- Air renewal represents the second essential lever because it increases the dilution rate of contaminants by reducing the overall concentration of particles present in a room.
- The organisation of the airflows complements this setup with, for example, the implementation of unidirectional airflows or ceiling supply systems in order to direct particles towards the extraction areas.
- Finally, differential pressure management makes it possible to control air transfer between different zones. Depending on the risk analysis, a zone can be maintained at positive pressure to protect it from its environment, or at negative pressure in order to limit the dispersion of contaminants to adjacent rooms.
These principles fit into a precise regulatory and technical framework. In France, NF S 90-351 defines requirements relating to the control of airborne contamination in controlled environment areas of healthcare establishments. It relies in particular on the NF EN ISO 14644 series, part 1 of which defines the classification of airborne particulate cleanliness.
A comprehensive approach to infection risk management
It should nevertheless be remembered that air treatment does not, in itself, constitute a solution for the prevention of healthcare-associated infections. It forms part of a comprehensive risk management approach involving, in particular, hospital hygiene, the organisation of the movement of people and equipment, cleaning and disinfection, environmental monitoring and the maintenance of installations.
In this approach, the design, sizing, qualification and maintenance of air treatment systems contribute to the control of airborne contamination in cleanroom environments. At A2I, our air treatment solutions are designed to meet the aeraulic performance criteria defined for each project and support the control of healthcare environments.
