DIAMOND BAR, CA — California’s air quality board has left intact a stringent smog-fighting standard for new buses but will allow transit agencies to keep buying more highly polluting diesel buses as long as they compensate by retrofitting some old ones, according to the Los Angeles Times. Because no diesel engines will be able to comply with an emission standard scheduled to go into effect in 2007, the Air Resources Board considered easing the standard to allow new diesel buses to emit six times more nitrogen oxides until technology improves in 2010. But in a unanimous vote after six hours of debate and public testimony, the board decided that relaxing the standard would be the wrong message to send transit agencies, according to the Los Angeles Times. The board members decided that transit agencies could buy buses that exceed the standard, but only if they offset the extra emissions by putting smog-control devices on some of their older diesels. If the board had not granted such an exemption, about 40 California transit agencies that rely on diesel buses, largely in Northern California, would not have been allowed to buy any new ones for three years.