Some positive past trends are reported with regard to sulphur oxides, non-methane volatile organic compounds, ammonia and particulate matter, although reduction of nitrogen oxides has been compromised by the difference between estimated emissions and real driving emissions from diesel vehicles.
O nekaj preteklih pozitivnih trendih se poroča v zvezi z žveplovimi oksidi, nemetanskimi hlapnimi organskimi spojinami, amoniakom in trdnimi delci, zmanjšanje dušikovih oksidov pa je preprečila razlika med ocenjenimi emisijami dizelskih vozil in emisijami pri dejanski vožnji.