Comment Log Display

1)If acrolein emissions are not mitigated through the ATCM, then
they will be identified for most construction projects proceeding
through the California Environmental Quality Act (CEQA) process as
an unmitigated significant environment impact.  This will trigger
the need for an Environmental Impact Report (EIR) and mitigation. 
The preparation of an EIR will be costly and time consuming. 
Mitigation will also be costly because each construction engine
equipped with a non-catalyzed diesel particulate filter will have
to be replaced by a catalyzed particulate filters at a cost of
around $10,000 apiece or more.  ARB staff has identified more than
175,000 construction engines in the State.  If only 10% required
changing, then the cost to the construction industry may be more
than $100,000,000.  In addition, this opens the door for further
increased costs if CEQA is used by opponents to stop projects. 

A provision in the Rule should be added that requires 90% organic
gas destruction so that acrolein emissions are mitigated.

2)When diesel PM was identified as a toxic air contaminant (TAC)
diesel particulate was used as a surrogate to estimate the health
risk for human exposure to whole diesel exhaust (e.g. solid
particulate and reactive organic compounds).  During the Railway
study, filters were used to collect solid particulate and the data
was used to develop the diesel PM cancer potency factor.  However,
we do not have sufficient test data to know whether the risk is
driven by exposure to solid particulate or the various air toxics
that are released in gaseous form, or the relative contribution to
the total risk from the organic compounds and solid particulate. 
The organic portion may be significant and, then, simply adding a
diesel particulate filter may miss a significant portion of the
health risk from exposure whole diesel exhaust.  In other words,
simply reducing the solid particulate will not necessarily result
in a proportional reduction in cancer risk.  If there are readily
available technologies that can be used to also reduce organic
gas, such as a catalyzed particulate filter, then this should be
considered during the rulemaking process. The contemporaneous
reductions in acrolein support the issue, but the overall concern
should be reductions in cancer risk from exposure to whole diesel
exhaust. Thus, ARB should encourage the use of catalyzed filters
whenever feasible for the current rulemaking.