Verify: Is 'rolling coal' legal in Oregon?

Videos of truck drivers intentionally blowing thick clouds of diesel fumes garner hundreds of thousands of views on YouTube. It's called "rolling coal," and it occurs when a driver modifies their engine to emit a dark plume of smoke, often targeting protesters, bicyclists and even Prius drivers. A KGW viewer named Michael Anderson asked us to Verify: Is it legal to "roll coal" in Oregon?
Published: 12:58 PM PDT March 12, 2019
Updated: 1:01 PM PDT March 12, 2019