Figure 4

Comparison of the p-PAH emissions from HDDVs determined in this study with those determined in (a) dynamometer studies and (b) tunnel and roadside studies. Emission factors of each p-PAH compound (left axis) measured in this study are presented in the form of five-number boxplot to reflect inter-vehicle variations, which consists of the minimum, first quartile, median, third quartile, and maximum values. Mean values of emission factors reported in previous studies are marked with the literature sources. Total p-PAHs emission factors (right axis) represent the sum of the fifteen p-PAH compounds detected from each study. Note: (I) dynamometer study of two vehicles with MI engines under steady conditions¹⁰; (II) dynamometer study of two in-use diesel trucks (model year earlier than 1996) under FTP conditions¹¹; (III) dynamometer study of a diesel fleet under transit conditions¹⁴; (IV) dynamometer study of a diesel fleet under cruising conditions¹⁴; (V) dynamometer study of vehicles with EI engines under UDDS conditions¹⁵; (VI) tunnel study at the Caldecott Tunnel⁴⁶; (VII) tunnel study at the Caldecott Tunnel¹⁷; (VIII) tunnel study at the Caldecott Tunnel⁴⁷; (IX) roadside study near the I-710; (X) tunnel study at the Caldecott Tunnel for ultrafine mode particles¹⁶; (XI) tunnel study at the Caldecott Tunnel for accumulation mode particles¹⁶.