Recital 4

(4)Once sufficient experience has been gained in relation to the implementation of Directive 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium, mercury, nickel and polycyclic aromatic hydrocarbons in ambient air ¹⁰ consideration may be given to the possibility of merging its provisions with those of this Directive.