Elected officials, business leaders and environmental watchdogs, invited by the editorial board, recently met at The Dallas Morning News to discuss clean air issues. This is the first of three excerpted transcripts from the roundtable. The speakers quoted: Colleen McCain Nelson, editorial writer; Margaret Keliher, Dallas County judge through 2006; Richard Greene, regional administrator for the Environmental Protection Agency; Tom "Smitty" Smith, director of Public Citizen's Texas office; Jim Schermbeck, Downwinders at Risk board member; Todd Campbell, director of public policy for Clean Energy and mayor of Burbank, Calif.; Al Armendariz, assistant professor, SMU School of Engineering; Robert Cluck, Arlington...