Nrdc 'Toxic' School Bus Study Aims To Push Cng; School Districts Want Clean-Diesel

Diesel Fuel News, Feb 19, 2001 by Jack Peckham

Natural Resources Defense Council (NRDC) and the Coalition for Clean Air (CCA) released a study last week claiming to show that school children suffer significant cancer risk from diesel emissions inside old school buses.

Working with natural gas lobby interests, both groups continue to push for bans on new diesel vehicles and instead favor costly mandates of compressed natural gas (CNG) or propane for all new buses and other public vehicles.

But school districts, school bus transport officials, chambers of commerce, oil refiners and others belonging to California's South Coast Clean Air Partnership (SCCAP) say the NRDC/CCA study instead points to the need for air-quality regulators to speed-up the replacement of old, dirty-diesel buses with new, relatively lower-cost, green-diesel buses.

However, South Coast Air Quality Management District (SCAQMD, metro Los Angeles) instead proposes to ban the purchase of new clean-diesel vehicles and force school districts to buy far more expensive CNG buses (see related story, below). SCAQMD's next hearing on its proposed rule is Feb. 21. That would mean many old, dirty-diesel buses will be left on the road because of large tax dollars diverted for a relative handful of costly CNG buses and new refueling infrastructure.

"By putting road-blocks in front of the use of new clean-diesel technology, the SCAQMD actually is making it harder for school districts to clean the environment for their students and the public," said SCCAP's spokesman Bob Sulnick.

The NRDC/CCA study only looked at four old diesel buses, not buses equipped with particulate matter (PM) traps. Recent studies show that catalyzed PM traps actually produce fewer toxic PM emissions than CNG buses, and a study at U.S. Department of Transportation shows that trap-equipped diesels would produce vastly more clean-air benefits per dollar spent compared to CNG (see Diesel Fuel News 9/25/200, p3; 9/11/2000, p12; 7/17/2000, p1).

None of these studies on CNG toxicity and cost problems are cited in the NRDC/CCA school bus report. Instead, the report claims that International's "green diesel" trap-equipped bus "has not been sufficiently tested to determine whether the new engine design has sufficiently reduced the toxicity of the exhaust."

Ironically, the NRDC/CCA report authors recommend the use of PM traps on existing school buses as a "short-term" toxics-reduction strategy. How this squares with NRDC's claim that "green-diesel" . PM-trap-equipped buses might not be safe on "toxics" isn't explained. Either trap-equipped buses are toxic; or they aren't, but they can't be both.

The NRDC report also claims "substantial concerns remain as to the durability and in-use performance of PM aftertreatment equipment for the full useful life of a school bus." Yet the report fails to mention that regulatory agencies require that manufacturers warranty such systems to work properly for the useful life. What's more, EPA discovered that "PM emissions deterioration that increases engine-out PM emission by 60% or more has little or no effect on post-CDPF [catalyzed diesel particulate filter] emissions," EPA said in its new diesel rule analysis (see Diesel Fuel News 1/22/2001, p9). This contradicts repeated claims by the gas/green lobbies that diesel in-use emissions deterioration would cancel. out gains from new engines.

What's more, recent emissions studies by the Northeast Advanced Vehicle Consortium, and separate studies at Environment Canada for the New York Metropolitan Transportation Authority comparing trap-equipped diesels to CNG buses, show that CNG has the highest in-use variability on NOx emissions, sometimes producing far more NOx than the in-use diesel buses (see Diesel Fuel News 3/6/2000, p6).

"Sadly, it is a typical publicity technique to heighten public concern for [the NRDC/CCA] agenda by sensationalizing the alleged adverse affects on children," the National Association for Pupil Transport (NAPT) "School Bus Information Council" said in response to NRDC's report. "Unfortunately, school buses appear to be caught in the middle of a bigger political battle in California," where the "greens" are trying to ban diesels.

"You don't want to frighten people into making decisions on the safety of those kids," NAPT executive director Mike Martin told us. That's especially true. since school bus transport is far safer than private vehicle or pedestrian modes for getting kids to school.

Green-diesel technology could provide even more benefits for child safety, at lower cost, Martin added.