Less than half of passengers wearing face masks on some Scotrail routes
ScotRail says around 90% of its customers have complied with the requirement overall since it was brought in on June 22 though.
Some train routes across Scotland are seeing just 40% of travellers wearing face masks despite them becoming mandatory on public transport a month ago.
ScotRail said around 90% of its customers have complied with the requirement overall since it was brought in on June 22, but it estimates only 60% - and in some cases just 40% - are doing so on some routes.
Syeda Ghufran, ScotRail engineering director, said: "While it's encouraging to see that most people across the country are following the requirement and covering their face when travelling, we need everyone to take personal responsibility for their travel choices.
"The mandatory wearing of face coverings helps keep you, your fellow customers and our people safe.''
The operator has also reported some passengers wear a face mask but then take it off while on board a service.
It has now applied face-covering vinyl to two of its Inter7City trains, which operate on routes connecting Scotland's seven cities, as a way to raise awareness of the rule.
ScotRail has also given away more than 20,000 free face coverings to help people get used to the new normal for rail travel.
Ms Ghufran added: "By applying a face covering to two of our iconic high-speed Inter7City trains, we hope to help raise more awareness about the mandatory wearing of face coverings on our trains and in our stations.''
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