The requirement for a face mask has been created on the basis of a recommendation from the Danish Health and Medicines Authority.
It can be punishable by a fine if one refuses to leave a means of public transport after being asked to do so due to lack of face mask.
It appears from an executive order on legal information .dk.
A fine shall be imposed on anyone who does not leave the means of transport, cf. section 1, or the station, etc., cf. section 2, subsection 1, after having been expelled in connection with the enforcement that transport companies etc., cf. section 6, make of the requirement for a face mask or visor according to travel rules, rules of order or the like, cf. section 6, nos. 1 and 3, it reads.
