Swabs were taken from areas most frequently touched by passengers, including the handles of escalators, ticket machines and benches, as well as one-hour air samples to detect virus.
London Euston, Birmingham New street, Liverpool Lime Street and Manchester Piccadilly station underwent two rounds of tests in January and June, with repeated tests on trains running between stations.
Experts from Imperial College London examined the results and found no coronavirus contamination of any virus particle on the surface or suspended in the air.
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Rob Mole, Senior Program Director for Network Rail’s Pandemic Response, said: “Station cleaning crews and train staff have made it their mission to ensure the safety of passengers during the pandemic and this is proof that their dedicated approach works.
“We want all passengers to travel with confidence on the rail network and we will continue to do our part by thoroughly cleaning trains and stations.
“We are asking passengers to do their part as well by wearing face coverings while traveling out of respect for others so that we can all stop the spread of COVID-19. “
The British have not been legally required to wear face coverings in environments such as public transport since the government lifted all COVID measures on July 19.
However, a YouGov poll last month showed that the majority of the UK public (71%) want face coverings to stay on public transport and are still required on certain services.
The poll also found that 66% of people want face masks to continue to be mandatory in shops and some closed public places, compared to 27% who thought they should be removed.
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David Green, Principal Investigator at Imperial College London, said: “In the same way that a swab is used to take a COVID-19 test in the nose and throat and sent to the lab, we use a filter to collect the viral particles. in the air and swabs to collect viruses on surfaces.
“This approach provides a way to quantify the amount of virus circulating in these public environments and the effect of mitigation strategies such as cleaning and wearing face coverings.
“This is part of a larger program of work with the public transport industry to understand where this virus is most prevalent so that we can resume pre-pandemic activities in the safest way possible. “
© Sky News 2021