UV-light sterilisation: A formidable weapon in the war on Covid-19?

Research shows that a specific band of UV lights can disinfect surfaces with 99% effectiveness

Even as Covid-19 cases continue to rise, India has lifted the lockdown to resume economic activity. The precarious situation makes a case for further precaution--wearing masks and social distancing. But it may not be enough.

Now, an old invention is making a comeback to help fight the novel Coronavirus’ alarming spread. Ultraviolet (UV) lights have been in use for quite some years as a means of sterilisation. UV-powered sterilising boxes meant for disinfecting surgical equipment have been in the market. Now UV lights are being expanded to be used en masse in ways not seen before.

For their disinfection properties, UV lights are being re-packaged as ceiling lights, used on top of light guns and even in light-emitting robots to disinfect everything from offices to hospitals, cell-phones and vehicles. In India, leading home appliances maker Havells, for example, is set to launch a range of UV light-offerings. Once out, the company expects these products to generate huge demand, akin to the sales of sanitisers right after the virus broke out.

“Our research shows UV-disinfection can have 99 per cent positive results, much higher than any other solution in the market,” said Prag Bhatnagar, senior vice president, Havells India.

Right now, offices and establishments rely on chemical sprays as the go-to means to disinfect premises. Organisations recommend obsessive use of sanitisers, temperature checks at attendance and masks at all times. While they help contain the spread, none of it is foolproof.

How does it work?

All of visible light falls within the spectrum 200-700 nanometer (wavelength), and of this 200-400 nm band is called UV light. This is further divided into UV-A (320 to 400 nm), UV-B (280 to 320 nm) and UV-C rays (200 to 280 nm).

For the purpose of disinfection, UV-C light is known to be optimal. That is because of its ability to break into cells. Specifically, it is able to destroy DNA, which is central to a cell’s survival, and renders microbes such as viruses and bacteria ineffective.

However, the disinfection process depends on three factors, said Bhatnagar. The intensity of light, duration of exposure and the distance (of a place you want to disinfect) from the source of the light. The combination of all these factors vary for different surfaces it is used upon and microbes it is used against.

Fitting them into consumer lighting is another challenge. UV light is harmful for humans and may cause minor skin burns, or defects in the eyes, from prolonged exposure. Also the out-cover of the light has to be made of quartz glass and not regular glass, which may perish under UV rays.

Consumer roll-out

For months Havells has been carrying out research on the UV lights from its R&D lab in Noida. “We have tested out different intensity, range and duration of UVs on different surfaces and have devised a formula of sorts,” said Bhatnagar. He added the consumer products that will be rolled out will have extensive directions for its safe use on the packaging.

“In one of the products, we have installed intelligence. Say a person walks in, the appliance will ring an alarm conveying that the area has just been sterilised from UVs so come back later,” said Bhatnagar.

The company was hush-hush about product specifics and a launch timeline, for competitive reasons. The product itself, while it could be used at homes, will be majorly targeted at offices, hospitals, airports, and other large infra-establishments, said Bhatnagar.

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