(20)The minimum ages of applicants for the various categories of driving licence should be set at Union level. Nevertheless, Member States should be allowed to set a higher age limit for the driving of certain categories of vehicles, in order to promote road safety further. Member States should, for certain categories and on an exceptional basis, be allowed to set lower minimum ages in order to take account of national circumstances, in particular as regards the driving of fire brigade, civil protection and rescue vehicles, as well as vehicles used for the purpose of maintaining public safety and order.