Commuters could face a chilly winter on trains as the industry is set to recommend windows are kept open to prevent the spread of coronavirus.
This is despite concerns being raised by scientists that coronavirus 'likes' lower temperatures and could have an impact on the severity of symptoms.
Evidence has shown that whilst ventilation is important, there was a decrease in the severity of symptoms in the UK as temperatures rose in the summer months.
Rail bosses are set to announce the measure in a bid to reassure commuters that trains are safe after seeing a decline of 400 million passengers during lockdown.
Ali Chegini, a director at the Rail Safety and Standards Board, said: “Even though it’s cold, even though you have to wrap up and put woolly socks on, it’s better to keep windows open than to be exposed to the risk of infection.”
He said four in every five trains had ventilation systems called HVAC, and that even if the windows do not open "moving air is better than not moving air in enclosed spaces."
Mr Chegini admitted that although the aim was not to "get everybody back on the train,” he said that: "If you need to be back at work and you've got a choice between road and rail, road is not the panacea that was originally, without justification, put out there."
This idea is due to be approved at Tuesday’s meeting of the Rail Delivery Group, where it could become mandatory for windows to be kept open during journeys and for carriage doors to be opened at stations to aid airflow.
Whilst improved ventilation will go some way to reassure passengers, in July government scientists decided that coronavirus spreads fastest at 4ºC amid the mounting concern over the threat of a winter resurgence.
A senior member of the Scientific Advisory Group for Emergencies (Sage) said Covid-19 “likes” four degrees best - “it survives well at four degrees [celsius]”.
Scientists are also understood to be increasingly confident that countries with temperate climates and with relatively severe flu seasons, such as Britain, will also be affected worse by Covid-19 in winter.
The maximum capacity of trains has dropped by between 45 and 50 per cent, with social distancing rules driving a loss in ticket revenue estimated at £700m a month.
Last month the standards board estimated that a passenger on a train where half of the seats were occupied could take 19,765 journeys without infection if they wore a mask.
The board has since revised these figures following risking infection and swab testing to say a passenger could take 5,000 coronavirus-safe trips on average.
This follows worries over air conditioning units reintroduced air back into rooms, potentially spreading coronavirus in enclosed spaces.
Earlier this year, experts told the Telegraph that air conditioning units that do not have a “dedicated source of outside air supply into a room… could be responsible for recirculating and spreading airborne viral particles into the path of socially distanced users”.
Dr Shaun Fitzgerald, a fellow at the Royal Academy of Engineering, said that even when using air conditioning units opening a window would be the best way to mitigate risk of infection.
Huw Merriman, chairman of the Commons transport select committee, said: "Hospitality and leisure businesses in cities are dying because we have not got commuters. Commuters are a hardy, stoic bunch, but we are also considerate. You only get confidence if you are realistic with the rule set and then people aren't seen to breach anything."
Susie Homan, a director at the Rail Delivery Group, said: "Hundreds of swab tests have been carried out so far showing no sign of Covid-19 on trains or stations and there are no reports of people getting the virus on the rail network."
The Department for Transport said it was researching "the risk of Covid-19 transmission on public transport [and] evaluating how to attract passengers back on to the railways at the right time."
Britain’s coronavirus-hit train network issue due to coast ministers up to £12 billion of taxpayers money following the scrapping of rail franchises.