Table 4 Percent decrease of in-bus exposures by bus types, relative to then 1983–2003 diesel bus class.

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

Pollutant Bus type Toronto Ottawa Vancouver
n % decrease 95% CL (LCL, UCL) n % decrease 95% CL (LCL, UCL) n % decrease 95% CL (LCL, UCL)
PM2.5 Electrica 0 0 313 40 33, 46
Hybrid diesel/electric 407 31 22, 38 242 25 15, 34 219 44 39, 49
Diesel 2007- 107 38 29, 46 598 ns ns 366 40 36, 45
Diesel 2004–2006 269 ns ns 276 ns ns 57 18 9, 27
Diesel 1983–2003b 147    415    405   
Ultrafine particles Electrica 0 0 307 ns ns
Hybrid diesel/electric 310 23 10, 34 218 36 24, 47 213 ns ns
Diesel 2007- 89 40 27, 50 586 ns ns 350 ns ns
Diesel 2004–2006 243 30 17, 40 241 ns ns 54 −22 −42, −5
Diesel 1983–2003b 79    392    386   
Black Carbon Electrica 0 0 269 30 19, 40
Hybrid diesel/electric 322 20 5, 32 243 43 33, 51 183 25 15, 34
Diesel 2007- 102 38 23, 50 581 24 16, 32 308 20 11, 29
Diesel 2004–2006 232 ns ns 275 ns ns 56 ns ns
Diesel 1983–2003b 146    398    388   
  1. “ns” denotes a nonsignificant increase in exposure, relative to the referent condition.
  2. aElectric buses were unique to Vancouver.
  3. bReferent condition.