Table 6 Estimated reduction of overall bus riding exposures with replacement of 1983–2003 buses with hybrid diesel/electric buses.

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

Pollutant City Bus riding exposures (mean (SD)) Estimated % reduction of riding exposures with fleet changeover
Sampled fleet With replacement of 1983–2003 buses
PM2.5 (µg/m3) Toronto 22.5 (9.9) 21.3 (9.9) 6.3 (5.2)
Ottawa 24.2 (12.6) 22.6 (11.4) 6.6 (4.8)
Vancouver 18.2 (5.5) 15.0 (4.8) 17.6 (7.5)
Ultrafine particles (103 pts/cm3) Toronto 15.8 (4.4) 15.2 (4.3) 3.6 (3.1)
Ottawa 18.3 (8.6) 16.7 (8.6) 10.7 (7.6)
Vancouver 16 (12.0)
BC (µg/m3) Toronto 3.1 (2.0) 3.0 (1.9) 4.6 (4.0)
Ottawa 2.6 (1.5) 2.1 (1.1) 12.7 (8.9)
Vancouver 2.6 (0.6) 2.4 (0.5) 9.9 (4.1)
  1. “–” denotes no evidence of lower UFP exposures in diesel/electric hybrids relative to the 1983–2003 class.
  2. aBased on estimates of % reduced exposure presented in Table 4.