An open letter from NEx Systems Founder & Head of Technology Steve Azvedo
By Steve Azvedo, Founder & Head of Technology at NEx Systems & NEx Viro (image - search results for "black light sterilizer" on Amazon - even though there's no such thing as a black light sterilizer)
As the Covid 19 pandemic has spread and become more entrenched in daily life, a new cottage industry of home-made hand sanitizers, office cleaning services and antibacterial products have come to market. While many of these products and services are pivots by reputable companies (NEx Systems, for instance launched our new NEx Viro service to highlight our 20+ years of expertise in environmental sterilization services), some have been scams – or products produced by amateurs with dangerous ingredients (the recent spate of toxic hand sanitizers come to mind).
Recently UV-C lights have begun to flood eBay, Amazon and other marketplaces with promises that coronavirus, germs and bacteria could be banished with the wave of a light wand. Unfortunately, it’s not that simple.
Don't be fooled by black lights – you can't see UV-C light radiation
UV-C light radiation was originally discovered in 1801 by a German physicist, but it wasn't until 1960 that it was found that specific wavelengths of UV-C light spectrum disrupted or inactivated DNA and RNA strands, thus rendering them unable to cause disease. This germicidal disinfection method has been adopted and adapted by various Industries over many years, especially healthcare industry providers. The UV-C germicidal process has been used as a sanitation standard in recent years to provide a chemical-free and effective method of sterilization in built and inhabited environments with sensitive populations, as well as applications for food, air and water purification.
UV-C light bulbs characteristically glow a brilliant blue hue, that looks somewhat similar to novel “dark” or “black/purple lights” – but it’s critical to note that the UV-C light radiation that actually kills germs and viruses is totally invisible to the human eye. The effective radiation emitted by professional UV-C lights are related to how much mercury vapor remains within the bulb and more specifically what wavelength the light emits – which can still appear brightly lit even when totally ineffective. Recently there has been a flood of black lights, fluorescent light wands and even real UV-C lights that are too weak to be effective sold to people as magical anti-viral light wands.
As this article in Discovery details, it’s critical that buyers beware: the only way to know if your UV-C light sterilization is actually killing germs and viruses is to conduct on-site surface testing – and to test the UV-C light as well. There are several methods of testing this; we at NEx Viro use the CDC-preferred ATP test method, where we swab samples from high-touch surfaces before, during and after our Reset Disinfection services to measure with certainty that we have eliminated 99.9% of pathogens. Additionally, the effectiveness of the UV-C light itself should be tested regularly using UVC dosimeter strips or similar exposure tests.
image: A NEx Viro technician tests UV-C sterilization effectiveness using a UVC dosimeter card at a job site
UV-C Light Sterilization - How it Works
The UV-C light spectrum is measured in wavelength nanometers, specifically 100 to 280 nanometers (nm). As a point of reference, there is the UVA light spectrum which is naturally emitted from the Sun down to earth at 315 - 400 nm and also the UV-B light spectrum at 280 - 315 nm. Depending on the application, a chosen particular range of "short" UV-C wavelengths, 222 - 254 mm, can provide varying degrees of the optimal antiviral effect.
But to properly sterilize using UV-C light, technicians must not only have the correct equipment, but also measure the volume of space, the distance between the light source and the surface to be decontaminated and take into account the porousness of the surface to insure proper exposure time…. All while wearing protective equipment (UV-C light can cause skin cancer). Ultimately, there must be a convergence of physics, technology, scientific, practical and operational measurement at the time of "on the ground" field application/operation.
image: a full UV-C light tower used at a recent NEx Viro Reset Disinfection
UV-C Light Sterilization is a Process – Not a Piece of Equipment
As with any technology, many claims and much hype can overwhelm the marketplace and the consumer with mixed messages. Recently, during this time of the pandemic, more than a few items imported from overseas, claiming UV-C germicidal light spectrum have been tested and proven to be ineffective. But in addition to the equipment there are a host of operational issues such as the power of the unit, distance to target and elapsed time required to ensure effectiveness of the UV-C process. From a training perspective, even high quality UV-C light units should not be considered as a piece of equipment, but rather as an instrument that requires proper operating procedures, safety protocols, measurements and testing. The tool without the training – and most importantly, the measurement on-site and in real-time – is really just a leap of faith; and with the stakes of improper disinfection being so high right now, that just seems like a risk few would want to take.
As we intuitively know about anything involving scientific instrumentation, the devil's in the details. There is so much more to know and learn about germicidal UV-C light spectrum technologies in order to fully leverage and harness all its potential capabilities. In the next conversation, we'll discuss the differences between the varying cause and effect ranges of germicidal UV-C light spectrums that can be thoughtfully designed and applied into our built and living environment .
Until then, be well and safe.
Owner / Technologist
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More info at https://www.nexsystems.com/nexviro