Ever wondered why the children who play out in the Sun are less susceptible to catching diseases than the ones who remain indoors? Ever pondered why hospital rooms often let a huge amount of sunlight in? Ever paid attention to why our grandparents would spend hours sitting in the Sun and advise us to do likewise?
In our primary schools, we must have learnt about the umpteen reasons why the Sun is useful for us. One of the many reasons it plays a vital role in our lives is the UV rays that it produces. Yes, the infamous UV rays which are often acknowledged as harmful are rather an important component of the Sun’s rays and are a natural germicide. Sunlight, or more specifically, solar UV radiations act as the principal natural germicide in the environment. UV radiation kills disease causing micro-organisms, or germs, by chemically modifying their genome.
In the present age of pandemic when the world is coming together in finding a way to conquer the harmful micro-organisms, there is probably a need to go back to the basics and find a solution there. The fact UV rays can decrease the viability of pathogens (including the new coronavirus) on surfaces is researched upon by many prestigious universities and the studies are quite promising.
The question that arises before us is, ‘how c an we make use of this germicide in the most effective manner?’. There are two major challenges that we face in this area. Firstly, most of the UV radiations of the Sun are filtered by the ozone layer of the environment making them readily unavailable for use. Secondly, most of the UV radiations found in ground-level sunlight are the UV-A and UV-B portions of the spectrum, i.e. 290 to 320 nm and 320 to 380 nm respectively, which offers lower efficiency in killing germs than the UV-C radiation which has the most effective wavelength, i.e. 260 nm, for inactivation of disease causing microbes including viruses.
Recent developments in LED technology have helped us overcome these challenges. The development of commercially available UV-C LEDs may be taken as a pathbreaking development in Ultraviolet Germicidal Irradiation (UVGI). A UV-C light-emitting diode (LED) is a semiconductor device that emits UV rays, with the wavelength range 260 nm to 270 nm, along with light when the current is passed through it. These UV rays warp the structures of the genetic material of the microbes making them inactivate and leaving them unable to perform vital cellular functions. As a result, these LEDs are an effective and a promising tool in disinfecting surfaces which are contaminated by several people.
As per a study done at University of California, ultraviolet LEDs that have the ability to decontaminate surfaces -- and potentially air and water -- that have come in contact with harmful microbes including viruses like Coronavirus causing diseases like COVID-19, SARS and MERS. The research states, ‘UV-C light in the 260nm - 285 nm range is the most relevant for current disinfection technologies. But since it is also harmful to human skin, so for now can mostly be used in applications where no one is present at the time of disinfection.’
A similar study carried out by the International Ultraviolet Association also argues that UVC can help prevent viral transmission by reducing contamination. It states, UVC light has been used extensively for more than 40 years in disinfecting drinking water, waste water, air, pharmaceutical products, and surfaces against a whole suite of human pathogens All bacteria and viruses tested to date (many hundreds over the years, including other coronaviruses) respond to UV disinfection. Some organisms are more susceptible to UVC disinfection than others, but all tested so far do respond at the appropriate doses.
Considering the science behind the efficacy of UV-C radiations in inactivation of disease causing microbes and also the studies which support the same, the coherence of UV-C LED technology with robotics seems to be a promising association in the new era of disinfection which demands not only perfection but also precision. UV-C based LEDs can help provide people around the globe safer living conditions.