Have vehicle emissions of primary NO2 peaked

摘要: Reducing ambient concentrations of nitrogen dioxide (NO2) remains a key challenge across many European urban areas, particularly close to roads. This mostly relates the lack reduction in emissions oxides (NOx) from diesel road vehicles relative reductions expected through increasingly stringent vehicle legislation. However, component near-road NO2 derives directly emitted (primary) vehicles. It is well-established that proportion (i.e. NO2/NOx ratio) exhaust has increased over past decade as result after-treatment technologies oxidise carbon monoxide and hydrocarbons generate aid control particulate. In this work we bring together an analysis NOx measurements with comprehensive emission remote sensing data obtained London better understand recent trends ratio We show there evidence have decreased since around 2010 despite less total NOx. The decrease shown be driven by relatively large amount vehicles; 25 vol% 15 2014 inner London, for example. shows these been reduced ratios heavy duty buses rather than light also Euro 4 5 passenger cars age decreases. For example 29.5 ± 2.0% up one year old 22.7 2.5% four-year At some roadside locations primary had effect on reducing both annual mean number hourly exceedances Limit Values NO2.