Rays of powerful ultraviolet light could help fight Covid-19, by zapping the virus on the London Underground.

Transport for London (TfL) is installing 200 UV cleaners on more than 100 escalators at its busiest stations, to help keep handrails clean.

A six week trial at Heathrow earlier this year found that the gadgets cut contamination on escalators by at least 50 per cent.

During the pandemic, this extra hygeine is crucial on surfaces that passengers touch, where there is a higher risk that germs could spread.

The new UV devices are attached at the top of escalators, and use the motions of the handrail to power them.

Ultraviolet is the same powerful light emitted by the sun, responsible for skin burns and cancers.

There are three types of ultraviolet radiation – UVA, UVB, and UVC. Only the first two reach the earth from the sun, with the most dangerous UVC rays filtered out by the planet’s atmosphere.

That UVC light is powerful enough to work as a disinfectant – it is already used to clean surgical tools, and can kill other strains of coronavirus.

Scientists have developed a narrow-range UVC light that can break down the molecular bonds of virus and bacteria DNA, without penetrating human skin.

While there has not been enough testing to prove the light works in the same way on Covid-19, TfL hopes it will help keep passengers safe on the Tube.

This Is Local London: TfL is installing UV light cleaners on more than 100 escalators (Photo: TfL).TfL is installing UV light cleaners on more than 100 escalators (Photo: TfL).

UV cleaners are already in place at King’s Cross, and will be installed at Bond Street, Charing Cross, Green Park, London Bridge, Paddington, Tottenham Court Road, Victoria and Waterloo.

Once complete, almost a quarter (24 per cent) of Tube escalators will have sanitising devices in place.

TfL is already using hospital-grade antiviral spray to clean its network, and more than 1,000 hand sanitiser dispensers have been installed for passengers to use.

Tests of the air and surfaces on the Tube and buses, conducted by scientists at Imperial College London, have so far found no trace of coronavirus.