VENTILATION SYSTEMS
Concerns over ‘naturally ventilated’ spaces
However, the Professor pointed out that many buildings were not even achieving current standards, and many ‘had no proper ventilation at all’. She also expressed particular concern about ‘naturally’ ventilated spaces – because they are dependent on wind direction and temperature, so cannot guarantee the target air change rates. Of course, hospital managers have been keenly aware of the risk of possible cross- infection caused by airborne contamination for many years. There is now, however, even more of a need to focus on the frequency of air filter maintenance and replacement to improve the effectiveness of systems, along with regular ductwork cleaning to reduce the build-up of particulate matter and biological contaminants.
An indoor particulate matter checker. Droplets
More information is also emerging about how air-conditioning systems hold in suspension the water droplets that transport the COVID virus; therefore SAGE is advising against using air- conditioning in places with low levels of ventilation. The improved handwashing and surface hygiene regimes introduced by many healthcare premises, along with air cleaning, are also not reasons to ventilate less.
Engineering controls should sit above measures that rely on human behaviour – such as distancing and wearing face coverings in any ‘hierarchy of risk control’, according to Professor Noakes. She also recommends that building managers address source control before studying ventilation requirements. This approach would not necessarily lead to increasing ventilation rates, but a more targeted strategy to ensure refreshed air was reaching all parts of the occupied space – and particularly patient recovery areas. Natural ventilation can leave ‘dead spots’, even when part of the room is well ventilated.
Measuring CO2 concentrations Measuring concentrations of CO2 is a
relatively straightforward way to establish whether a ventilation strategy is working, as it will act as a ‘canary in a cage’ for other contaminants.
To embed the lessons learned in the pandemic, the industry will have to find ways of proving that it is delivering the ventilation performance required in buildings, and demonstrate its compliance with the standards that will emerge. Part F of the Building Regulations, which is currently under review, could also be used to beef up the IAQ measures likely to be introduced in the forthcoming Environment Bill. The question of humidity control
18 Health Estate Journal September 2021
remains a challenge for Estates and Facilities managers, but it is one they must confront to ensure that buildings are properly equipped to deal with all future threats to health and wellbeing. Dr Stephanie Taylor from Harvard Medical School told a BESA meeting that managing the indoor environment was ‘the best medicine for treatment and prevention’. She said that numerous studies had identified an RH ‘sweet spot’ between 40% and 60%. Air that is too dry will allow viruses to thrive and be more active, she explained. She said: “We need to start regarding human health as a key measure of success for our buildings. When we speak, we expire droplets out of our airway that are about 100 microns in diameter. When they enter the air in the room, those droplets shrink according to the RH of the ambient air. If humidity is maintained at between 40% and 60%, the droplets shrink to a point where the concentration of salts in those droplets inactivates microbes.”
However, if RH is less than 40%, those droplets shrink even further and the salts preserve the microbes, making them more virulent. “One study at a pre-school showed that humidification decreased ‘flu infections. In fact, it showed that dry air causes infections,” said Dr Taylor. Other research has also shown that in low humidity indoor environments, the human body has difficulty fighting off infections – compounding these problems.
COVID-19 is not the only illness that thrives in our modern airtight and heated environment. There are also increases in inflammatory disorders, auto-immune disease, and allergies. Dr Taylor emphasised that there can be no doubt that the indoor environment is in the frontline in the fight against future pandemics. She said: “As a physician I’ve
come to realise that managing our indoor environment is the most powerful medicine both for treatment and prevention. The corollary of that is that building professionals really, in my opinion, are the physicians of the future.”
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Steve Tomkins
Steve Tomkins, head of Business Development at the Building Engineering Services Association (BESA), is a Chartered engineering leader, with over 20 years’ engineering maintenance and management experience working in the facilities management, construction, rail, and automotive sectors. Having worked in both small and multinational organisations delivering complex projects and solutions, he joined BESA in 2017 to spearhead the ongoing development of SGF20, the industry’s recognised standard for maintenance specifications.
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