Fig. 1
From: “Are we forgetting the smallest, sub 10 nm combustion generated particles?”
Upper panel: Normalized particle size distribution functions measured in the bluish (full diamond) and in the sooting region of an ethylene-rich/air flame (empty circle), and at the exhaust of a common-rail Diesel engine at half load with (grey triangle) and without (line) a particulate filter (DPF). Flame data adapted from Echavarria et al. [26]. Engine data adapted from D’Anna A. [1] & Gualtieri M. et al. [18]. Lower panel: Normalized particle size distribution functions measured on-road (empty triangles) and in vehicles plumes (gray triangles) or following the vehicle with a “sniffer” laboratory vehicle with (full diamonds) and without (empty circles) a thermodenuder. On-road data adapted from Kittelson et al. [22]; vehicle plumes adapted from Yao et al. [23]; “sniffer” data adapted from Ronkko et al. [4]