Biomedical Engineering Reference
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other particulates decreases. Particle numbers are far lower at 20 and 38 m than they
are closer to the ground.
Finally, Figure 5.3 shows estimated particle emissions from idling school buses
(Kinsey et al. 2007). Although emissions vary widely among buses, in all cases the
majority of particles are smaller than 1 micron, and every bus produced particles in
the nanometer range.
0.80
Bus 203
Bus 255
Bus 256
Bus 259
Bus 260
Bus 288
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
10
100 1000
Aerodynamic particle diameter (nm)
10000
(a)
0.80
Bus 203
Bus 255
Bus 260
Bus 288
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
10
100 1000
Aerodynamic particle diameter (nm)
10000
(b)
FIGURE 5.3
(a) Continuous idle and (b) Post-restart idle. Nanoparticles in diesel emissions:
School bus idling. Average mass-based particle size distributions for continuous idle. The
buses were manufactured between 1997 and 2004 and measured in March 2005. (Reprinted
with permission from Kinsey, J.S. et al., Characterization of fine particle and gaseous emis-
sions during school bus idling,
Environ Sci Technol
41: 4972-4979. Copyright 2007 American
Chemical Society.)
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