California grossly miscalculated pollution levels in a scientific analysis used to toughen the state's clean-air standards, and scientists have spent the past several months revising data and planning a significant weakening of the landmark regulation, The Chronicle has found. Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/10/07/BAOF1FDMRV.DTL#ixzz11lygIi8k