(Salem, OR)  --  Nearly a dozen big wildfires in Oregon are fouling the air in the Willamette Valley.  The Statesman-Journal reports that smoke is expected to hang over the Rogue Valley for the rest of the week.  That smoke is drifting northward, prompting regulators to warn of moderate air quality in Eugene and Salem.  The Oregon Department of Environmental Quality says moderate air is acceptable, except for more vulnerable people.