Reflect on the possible reasons for the differences in
source contributions to lead (Pb) emissions shown in Figures 28.19, 28.20, and
28.21 since the 1990s. Review the literature for US and European sources of
lead during this time, e.g. the USEPAs Air Pollution Control Orientation
Course. Why did the relative contribution of mobile sources fall sharply over
the past three decades?
Figures 28.19, 28.20, and 28.21