Table 1 Contribution of bus commute to daily exposure of PM2.5 mass and elements.

From: Personal exposures to traffic-related air pollution in three Canadian bus transit systems: the Urban Transportation Exposure Study

Element Mean (SD) % contributiona
Toronto (n = 18) Ottawa (n = 18) Vancouver (n = 17)
PM2.5 6 (2) 13 (10) 11 (4)
Al 26 (11) 32 (23) 38 (15)
As 7 (3) 5 (3) 8 (2)
Ba 59 (15) 60 (20) 57 (18)
Cd 8 (7) 10 (9)
Cr 27 (21) 19 (18)
Co 21 (9)
Cu 30 (15) 37 (9) 32 (7)
Fe 70 (19) 64 (15) 70 (15)
Mn 27 (14) 23 (13) 18 (9)
Mo 17 (12) 24 (7) 22 (6)
Ni 15 (11) 22 (16) 14 (9)
Pb 12 (6) 10 (5) 18 (13)
Sb 12 (4) 10 (6) 36 (10)
Se 4 (2)
Sn 17 (4) 19 (8)
Sr 20 (9) 26 (15) 24 (9)
Ti 39 (14) 41 (19)
V 6 (2) 8 (5) 13 (6)
Zn 10 (9) 12 (11) 8 (2)
  1. Full table can be found in Supplementary (S8A, B, C).
  2. aPercent contribution of 66-min bus commute (4.6% of day) to overall daily exposure (Eq. 1).