Urban environment diagnosis upstream a district development in a medium-sized European city: Analysis of carbonaceous particle pollution captured by mobile measurements

In France, fine particulate matter (PM) pollution is estimated to be responsible for 40,000 premature deaths per year. If PM₁₀ (d < 10 µm) and PM_2.5 (d < 2.5 µm) size fractions are regulated at the European level, this is not the case for the carbonaceous particle pollution, namely Black Carbon (BC). However, according to the WHO, BC is highly toxic for human health. Moreover, BC can be considered as a good proxy for resident exposure in urban environment as this pollution originates from traffic, residential heating or industrial activities. This study focuses on the BC diagnosis at a district scale, upstream of its sustainable development in Dijon Metropolis, Eastern France. Mobile BC measurement campaigns were carried out between February and mid-April 2024 during days and hours representative of typical urban pollution conditions, using the MA-200 mini-aethalometer. The results show that BC levels are typically urban (1-3.2 µg/m³), and are higher than background levels in Dijon metropolis (annual averages of 0.7-0.8 µg/m³). The studied area is characterized at 75% by pollution linked to the fossil fuel combustion (BC_ff), mainly related to road traffic. The contribution from the wood burning component (BC_wb) is relatively marked in winter (34% of total BC, compared to 18% in spring) due to the effect of residential heating. Finally, the spatio-temporal variability of BC is induced by land use at the fine scale (street, neighborhood) and wind speed at the city scale. These results highlight the original insights of BC mobile measurements to characterize the particulate pollution in an urban context. Even though the BC concentration levels are very low compared to PM_2.5, their strong spatio-temporal variability at micro-scale makes it possible to identify pollution “hot-spots” and their origin. Thus, the BC evaluation at fine scales may help in the planning of sustainable urban development strategies.