NRDC: No Breathing in the Aisles: Diesel Exhaust Inside School ...

EPA’s new heavy-duty engine standards will dramatically reduce diesel
emissions, but not until the 2007 to 2010 phase-in of the new standards
While a Consent Decree with most of the major engine manufacturers will result in a
reduction in NOx and NMHC emissions in new diesel engines by October 2002 (to
2.5 g/bhp-hr), the greatest NOx and PM reductions for new diesel engines will be phased in
between 2007 and 2010, under regulations recently adopted by EPA. 116 Under these standards,
new diesel engines will need to meet a more stringent 0.2 g/bhp-hr standard for Nox
(a 95 percent reduction) and a 0.01 g/bhp-hr standard for PM (a 90 percent reduction). While
we strongly support the new standards adopted by EPA, these standards are at least seven
years away, and no current diesel engines—certified or in concept—can meet these standards.
Moreover, manufacturers of natural gas engines expect that by the time diesel engines
become cleaner (likely by 2007), alternative fuel engines will become cleaner as well. For
example, the same particulate traps being developed for diesel engines can also be installed on
natural gas engines and would reduce particulate emissions virtually to zero. Thus, while
diesel engines will continue to become cleaner over time, there will be a continuing challenge
for the diesel industry to keep up with the public health benefits of alternative fuels.
32