any stationary source of which the construction or substantial modification is commenced after the expiry of one year from the date of entry into force of the present Protocol. It shall be a matter for the competent national authorities to decide whether a modification is substantial or not, taking into account such factors as the environmental benefits of the modification., paikne saasteallikas, mille ehitamist või olulist modifitseerimist alustati pärast kahe aasta möödumist protokolli jõustumisest