INF ECTION P R EVENTION
in particular should be re-evaluated.” It has also raised the issue of ventilation in wards and the areas adjacent to them, and whether that should also be significantly improved.
HTM 03-01 is the current standard for ventilation for most patient care areas in hospitals where specialist ventilation arrangements are not required. The standard dates back to 2007, and therefore does not take into account the latest thinking on the need for clean-air design within most patient accommodation. That includes the types of modular buildings increasingly used by hospitals to house patients.
When it was produced in 2007 the use of modular buildings was very limited, but now they are seen as a vital tool for increasing healthcare facilities. An updated version of HTM 03-01, due for publication early in 2021, has received specialist input to address the latest thinking on clean-air requirements in patient accommodation. The availability of high-quality modular buildings has been a huge advantage for hospitals and health Trusts, faced with
urgent need for additional facilities and increased pressure on funding. Rapidly deployed modular buildings can offer a design life of up to 60 years but can be delivered in a fraction of the time taken for conventional build methods, making them an attractive option. However, there is a concern that the drive to get the best value is often characterised simply by the lowest price or fastest turnround, without taking into account vital requirements for patient care, in particular infection control ventilation. One area of primary concern is ensuring that ventilation of modular buildings is compliant with the highest standards and not simply meeting the minimum requirements within HTM 03-01 guidance documents. Many modular buildings are supplied with no mechanical ventilation or air-handling systems. That may be considered adequate ventilation to meet those minimum standards. But adequate and appropriate are not the same thing. Specific clean-air handling design for the internal configuration of each building accommodating patients should be a
requirement to ensure appropriate air flow. Ventilation is a crucial tool to protect patients and staff from the spread of potentially harmful pathogens and ensure their comfort and safety. When specifying a modular building and choosing a supplier, health Trusts need to carefully evaluate the need for clean-air ventilation and its impact on each specific space configuration. The underlying concept of factory-built accommodation is rapid production for a mass market at the cheapest price – not specifically designed and engineered modular building solutions for the medical sector. Professor Cath Noakes from the School of Civil Engineering at the University of Leeds addressed the virtual Healthcare Estates Conference in October 2020 on the issue of ventilation. Professor Noakes leads research into ventilation, indoor air quality and infection control in the built environment. She acknowledged that at that time there was little data from real-world medical settings about COVID-19 transmission, but evidence from community settings showed the highest risk is probably within indoor environments and over short ranges – a view now reinforced by the new research. In addition to droplets settling on surfaces, and the virus transmitting directly between people during physical contact; there is also evidence of airborne transmission of COVID-19, particularly in poorly ventilated spaces. People are at their most contagious when they are largely asymptomatic, so that it becomes increasingly important to consider ventilation of spaces housing patients. Professor Noakes pointed out that airborne aerosol particles need drag force to keep them up and gravity to bring them down. But air velocity in a room is known to impact on this and various-sized particles can remain in the air for a significant amount of time, often travelling quite far from their original source – particularly when driven by patient coughing typical in someone suffering from COVID-19. That is where clean-air ventilation can have a significant impact. “If a space is well ventilated you can’t completely contain the virus, but the ventilation will dilute the virus and the risks are technically lower,” reasoned Professor Noakes.
Clean air flow path 30 l
WWW.CLINICALSERVICESJOURNAL.COM
This view is reflected in the Federation of European Heating, Ventilation and Air Conditioning Association’s recently updated REHVA COVID-19 Guidance Document, which cites ventilation as the principal engineering control to help control infection, thus giving further weight to the vital role ventilation plays in the COVID-19 response effort. It states that, in hospitals with an optimal 12 air changes per hour (ACH) ventilation rate, aerosol transmission is mostly eliminated. But, in poorly ventilated
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