On the impact of excess diesel NO_X emissions upon NO₂ pollution in a compact city

Abstract NO X emissions from diesel light-duty-vehicles (LDV) largely exceed the Euro emission standards in real-world driving conditions. Recent studies have quantified their impact upon air quality and human health primarily based on models at mesoscale large-scale resolutions. Here, we show that these approaches can significantly underestimate of LDV excess 2 pollution cities, particularly more compact heavily trafficked ones. We compare an model both 4 1 km resolution with a street-scale Barcelona, city where EU annual limits are repeatedly exceeded large share passenger cars (65%). consistently two scenarios: business-as-usual scenario emit excess, counterfactual standard compliant standards. first contrast to model, street scale is able represent observed concentration gradients between traffic background stations city. In second step, find strongly underestimates absolute terms (by 38%–48%) relative 10%–35%). argue such underestimated impacts should be considered when assessing by cities. Using associated about 20% levels city, contributing substantially increased number citizens exposed high Barcelona.