Summer days and outdoor living helps us to forget about covid. When autumn returns and we gather indoors the risk of infection will rise again. It has always been this way with colds and flu. Now we have a determined enemy that won’t release us from its grasp. The scientists know that ventilation is the key. The UK governments advisory group SAGE* have directed building operators to address this problem. Whilst open windows are being advertised as a good solution to dilute infected air, in many situations this may not be practical due to winter climate Air-conditioned buildings are exercising the minds of engineers around the world.
From the recent avalanche of publications two in particular have emerged to address the problems faced by building owners. The Royal Academy of Engineering and the Chartered Institution of Building Services Engineers have both published comprehensive documents to address this problem. In both reports the issue of how to deal with spaces with inadequate ventilation are examined and in particular all the best types of stand alone air cleaning devices. In both reports the use of UV light is seen as a good solution whilst warning about the array other technologies and products often placed on the market with little supporting science or in some cases with detrimental by-products.
Links to the full reports are given below together with abstracts.
Engineers have been tasked by the UK Government Chief Scientific Adviser to undertake a review of actions to make infrastructure more resilient to infection **
The Royal Academy of Engineering and National Engineering Policy Centre.
Infection Resilient Environments:
Buildings that keep us healthy and safe
“Ultraviolet light (UV) – the short wavelength of germicidal UV (UVC) can deactivate the infectious abilities of cells. For air cleaning this requires sufficient exposure of the microorganisms to the UVC light, which can be achieved with slow moving air or with sufficient intensity lamps. There is some confidence that UVC air cleaning devices may be a useful strategy to reduce airborne transmission, these are most useful in poorly ventilated spaces”.
See Annex A page 15
Full report at:-
CIBSE – Chartered Institution of Building Services Engineers
COVID-19: Air cleaning technologies
“that portable air cleaning devices based on mechanical filtration (such as HEPA filters or UV-C) are ‘likely to be beneficial if deployed correctly”
“…review of current scientific evidence demonstrated that devices whose operation relies on ionisers, plasma, chemical oxidation, photocatalytic oxidation or electrostatic precipitation may generate undesirable secondary chemical products that could lead to health effects such as respiratory or skin irritation (SAGE-EMG, 2020). Echoing SAGE- EMG advice and scientific evidence, devices relying on these technologies are not recommended “
Section 4.4 page 8
Full reports at:-
**UK Government SAGE* Advisory Group
SAGE-EMG 4th November 2020
Potential application of Air Cleaning devices and personal decontamination to manage transmission of COVID-19
In a report commissioned by the Government Chief Scientific Adviser, Sir Patrick Vallance, leading engineers say the importance of ventilation is too often neglected, and that the Covid-19 crisis has revealed flaws in the way in which we design, manage and operate buildings.
The report warns that technological solutions are not a ‘silver bullet’, and uninformed reliance on technology can even have negative consequences. For example, air cleaning using high efficiency particulate air (HEPA) filters or ultraviolet light (UVC) can be effective at reducing infection risks in locations where good ventilation is difficult to achieve. However, the benefits are of using other kinds of air cleaning devices, often heavily marketed, are less clear.
Full Report at: