UV light as one of the weapons against coronavirus

In response to the COVID-19 outbreak, governments and companies across the world are taking to several sanitation practices including a solution that has been in use for decades for effective disinfection – ultraviolet (UV) light.

Prag Bhatnagar

As the world is trying to come to terms with the ‘new normal’ after the outbreak of the COVID-19 virus, there is a greater need for technologies that will equip us to protect ourselves. While working from home, social distancing and wearing masks become accepted social norms, the pandemic has brought the significance of cleaning and disinfecting to the fore. Regardless of when the lockdowns across the world are lifted or eased, it is evident that this health crisis has shaken people’s confidence and that there is an increased need for more effective tools and services to disinfect spaces around us. In response to the outbreak, governments and companies across the world are taking to several sanitation practices including a solution that has been in use for decades for effective disinfection – ultraviolet (UV) light. But before we get into how UV is beneficial, it is imperative to understand it better.

Understanding Ultraviolet Light

Ultraviolet lights have shown great promise in providing effective disinfection of surfaces. However, not all UV lights are effective for sterilisation and disinfection purposes. The full range of UV radiation is sourced from the sun and it can be subdivided into UV-A (320 to 400 nm), UV-B (280 to 320 nm) and UV-C rays (200 to 280 nm). For disinfection purposes, the optimum wavelength required is in the region of 260 nm to 275 nm, with germicidal efficacy falling exponentially with longer wavelengths. The reason why UV radiation is effective in disinfection is because it has enough energy to break DNA chemical bonds. UV-C radiation, in the range of 260 nm – 275 nm, destroys the genetic information stored in the DNA and hence renders harmful micro-organisms such as bacteria and viruses ineffective. DNA and RNA are the building blocks of life for pathogens such as viruses and bacteria as well and without this genetic material, these pathogens are unable to reproduce which eventually leads to the death of an infectious colony.

The wavelength, power intensity and exposure duration are some of the key factors used to determine effectiveness of UV light against microbes. For example, on surfaces and in water, there might be several germs with varying optimal absorption wavelengths. For any given wavelength of Germicidal UV (GUV), its power and exposure duration would need to be determined in order to achieve the desired level of sterilisation.

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While developing a product for a specific disinfection need, it is imperative to gauge the performance of UV LEDs under different conditions and how these conditions are related to one another. While power and wavelength are the first factors a design engineer considers, these are not the only factors to be assessed. The viewing angle, wavelength and radiation pattern provide insights with respect to the usefulness of the power specified and current related information provide room for control and design of the system for end of life requirements. Lastly, thermal related information like thermal resistance and maximum junction temperature are important specifications for development of an efficient and application-specific thermal management.

GUV is ideal for deployment in hospitals, offices, parking areas, hotels, warehouses, train stations etc. to make the manual sanitisation process more effective. GUV LED light prototypes for B2B usage can be used as a retrofit in different types of fixtures.

Is it safe for humans?

UV-C only penetrates the upper layers of the skin and eye, with the shortest wavelengths hardly penetrating at all to living cells, thus it may cause only a mild, transitory sunburn from accidental over-exposure to skin. Even though GUV lamps may pose a theoretical delayed hazard, incidental UV exposures would not significantly increase one’s lifetime risk for cataract or skin cancer when compared to exposure to UV light from the sun on a daily basis. As a precautionary measure, it is important to not enter the disinfected area after 30-40 minutes of operation of the GUV lamp. Also, one should also not look directly into the disinfection lamp to prevent damage to the eye. The products developed using the technology will also have to be intelligent keeping in view requirements of daily usage.

Also Read: Covid-19 crisis greater in congested cities: Study

Looking at accelerated UV usage

While some effects of the pandemic may be short-lived, the emphasis on cleanliness is going to stay. Consumers will remain conscious of hygiene and it will actively influence their purchase decisions such as which mall to shop in, where to dine and which hotel to stay in the future. The global UV disinfection equipment market was valued at $1.1 billion in 2018. According to Allied Market Research, it is projected to reach $3.4 billion by 2026. Adoption of sanitation technologies such as GUV is only going to increase. There is a reason why public places such as the Delhi Airport have picked up ultraviolet light technology for disinfection. Slowly, we are likely to see an accelerated adoption of technologies like GUV not just in hospitals and public spaces but also common households.

Prag Bhatnagar is Senior Vice President, Havells India Limited.