http://www.kqed.org/.stream/anon/radio/quest/2008/12/2008-12-08-quest.mp3
That black, sooty exhaust from old diesel trucks may be a thing of the past. A landmark decision expected next week at the state Air Resources Board would mean California truckers must retrofit their diesel rigs at a price tag of about $5 billion. The cost is high, but given the health complications from diesel emissions, air pollution regulators feel they can't afford not to act.