UNITE has re-iterated its call for face coverings to be "mandatory on all forms of public transport".
The union said a move by the Executive to consider whether to make face coverings compulsory on designated school transport services does "not go far enough".
Michael Dornan, Chair of Unite’s Metro driver branch, said: "Since May, Unite has been calling for face coverings to be made compulsory for passengers for all forms of public transport in Northern Ireland.
"We understand that the Northern Ireland Executive is considering making the wearing of face coverings obligatory for school children on designated school runs but this does not go anywhere far enough," he said.
"Many school children use a variety of services, often changing between modes, using rail and bus services to get to school.
"In Belfast only approximately 40 per cent of schoolchildren get to school on designated services. We need to see face coverings become mandatory for school children, indeed all passengers, on all modes of public transport".
Adrian Kelly, chair of Unite’s branch of Northern Ireland Rail drivers, said face coverings must be made mandatory in order to "minimise risk to others".
"The latest evidence suggests that there is an elevated risk of transmission from school children when they gather in areas also frequented by adults," he said.
"In order to minimise risk to older passengers, our drivers and to protect our public health service, we need to see face coverings become mandatory on all forms of public transport".
