Think Long-Term on Diesel

Get stuck behind--or inside--one of the 24,000 school buses on the road in California and you may be enveloped in a swirling black-gray cloud of exhaust each time the driver hits the accelerator. Diesel exhaust, whether from yellow school buses, city trash trucks or diesel cars, is a known cancer-causing agent. Short of causing cancer, the sooty exhaust can aggravate asthma and lead to loss of lung function.

In recent months, state and local air quality officials have adopted far-reaching rules to cut overall diesel pollution by switching to natural gas. Extending those rules to school buses is the next item on their agenda.

Next year, the South Coast Air Quality Management District is likely to include school buses under fleet rules it adopted this year, requiring government agencies to buy only alternative-fuel new trucks, buses and cars. Most will be powered by natural gas. AQMD officials had delayed extending this rule to cash-strapped local school districts, but Gov. Gray Davis set aside $50 million in this year’s budget to help pay for new clean-fuel school buses statewide. With that money now available and much of it allocated to Southern California, the AQMD should act.

More immediately, however, the California Air Resources Board needs to set ground rules that wring the greatest clean-air benefit from these funds. A staff proposal due before the board at its meeting next week does not move far enough in that direction.

Under the proposal, $10 million of these funds would buy soot traps to clean up 1,500 buses already in use. Given the long road life of school buses and the $100,000-plus cost of new ones, that decision makes sense. School districts will also get $40 million to help buy some 400 new buses. The air board would require $25 million to go toward the purchase of natural gas buses but would permit $15 million to go for so-called green diesel buses. These run cleaner than existing diesel buses but not as clean as natural gas vehicles.

If the green diesel buses are to find a use, it should be in rural, not metropolitan, districts. Another key issue is that since almost all the vehicles are produced by Chicago-based International Truck and Engine Corp., the air board’s nod toward this technology in effect becomes a $15-million windfall for one vendor. That should make both taxpayers and state officials uneasy.

With air quality agencies finally moving to clean up toxic diesel emissions after years of inaction, California needs to spend wisely to produce the greatest gains over the long term. That means embracing natural gas buses rather than locking school districts into a halfway solution like green diesel.