The lower polluting formula sets a new sulfur maximum as a national standard, cutting it drastically from 500 to 15 parts per million. California refineries began trickling this into the pipeline system in June. By September 1, all gas stations in the state must have only the new diesel. Refiners in other states have additional years to comply.
Lower sulfur means less soot and smog. The impact won’t be huge. Advanced emissions control systems will be more helpful. Truckers had been worried about added expense, but with fuel prices bouncing up and down every week, that’s been a non-issue.