FEATURE LIGHTING AND ILLUMINATION
‘If you talk to people who have actually studied this technology, you’re generally going to get something much higher calibre’
Avantes’ spectrometers steer different colours of light – including ultraviolet – onto separate paths g
be marketed as something you can sweep across the surface for two minutes or so,’ John stressed. The wands should also have gravity-sensing switches that turn off the light when it’s turned towards a user, to protect their eyes. However, only one of the seven wands had this switch and delivered enough UV-C to kill germs quickly. LIA has now supplied these results to Public Health England.
Safety aware While there are many poor products out there, there are also some that should do the job intended, John emphasised. ‘There are plenty of good products out there that have been created by people who do actually know what they’re doing and are getting good market penetration,’ he said. ‘If you go and talk to people who
have actually studied this technology, for instance members of the IUVA, you’re generally going to get something which is much higher calibre.’ The LIA has also tested UV light
boxes, which can be equally ineffective, John noted. It has also assessed trolley- mounted devices carrying 18 UV-C tubes. These achieve the desired kill rates in a very short time, John said, but also require safety devices that ensure they don’t operate when people are nearby. ‘It’s very easy to kill micro-organisms with UV – the difficult bit is not harming human beings while you’re doing it,’ he said. To verify safety, Fowler recommended using measurement systems like the ILT960UV-RAA4, using threshold limits specified by the American Conference of Governmental Industrial Hygienists. UV
spectrometers that include proper input optics and calibrations are excellent tools for verifying both the wavelength and the irradiance that is being emitted, Fowler explained. ‘For disinfection, it is best to verify where the risk is greatest and the light may have a harder time reaching and extend exposure times, so that the harder to reach areas are getting the proper dosage,’ she said. To help suppliers, ILT offers testing of UV wands and other smaller devices and cabinets, as well as sales and rental of UV meters and spectrometers, Fowler said. She has the following advice for how
potential buyers of UV disinfection equipment can ensure that systems meet their needs but don’t cause extra health problems. ‘First and foremost, you cannot see UV, so be prepared,’ she said. ‘Goggles and skin protection should be used, or leave the area during use. UV is highly reflective and will bounce around and off of surfaces. It may also leak out of the side and back of hand-held devices, causing high risk of eye and skin damage. Second, check customer reviews for the product and company. Third, and no less important, does the source produce enough dose to be effective for the item or area being disinfected? If the supplier does not list a dose, dose time and/or irradiance and cannot provide any testing value, do not buy. Last, consider buying a UV meter to assure your UV levels are fairly stable during the testing and over days, weeks and months of use.’ Fowler’s advice is ‘trust but verify’. She said: ‘If you are going to implement UV in your disinfection protocol, be sure to have a means of verifying the safety of the personnel in the area, such as the ability to leave during treatment, and that the required dose is being supplied to the furthest area from the source.’ EO
Reference 1
M Darnell, K Subbarao, S Feinstone and D Taylor 2004. Inactivation of the coronavirus that induces se- vere acute respiratory syndrome, SARS-CoV. Journal of Virological Methods, 121(1), pp.85-91.
2
The LIA found just one out of seven UV wands bought online safely delivered UV light in a large enough dose to kill germs
14 Electro Optics March 2021
M Buonanno, D Welch, I Shuryak and D Brenner, 2020. Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses. Scientific Reports, 10(1).
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Avantes/Pro-Lite
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