The mass concentrations and carbonaceous content for the
four PM size fractions are shown in Table 2. On average, PM2.5
accounted for 88% of the PM10. The size range lower than
0.5 μm encompassed the largest mass fraction of PM10 (56%),
while the aerodynamic diameters below 1 μm included 70% of
the aerosol mass. Results from dynamometer studies involving
passenger cars and light-duty vehicles (Chiang et al., 2012)
revealed a higher contribution of the finest size grains to the