Within 24 months from the date of adoption of this Directive , the Commission shall submit to the European Parliament and to the Council a proposal prepared on the basis of research and an assessment of the costs and benefits deriving from the application of tightened - up limit values and laying down a subsequent stage during which measures will be adopted aimed at further tightening of the limit values for pollutants and the sound level of the vehicles concerned , as laid down respectively in Chapter 5 , Annex II , Tables I and II and Chapter 9 , Annex I.