Part 1: Federal underpinnings of state fuel quality standards

The Environmental Protection Agency (EPA) currently enforces limits for lead, manganese, phosphorus, sulfur and benzene, as well as regulates the inclusion of detergent additives in gasoline.

The limits on lead, phosphorus and manganese are long-standing, having been written into the Clean Air Act (CAA). Limits on sulfur and benzene, on the other hand, have been subject to ongoing rulemaking by the EPA. The most recent change in limits on these two parameters came with promulgation of the Tier 3 Gasoline Sulfur program in 2014. It lowered the yearly average limit on gasoline sulfur to 10 mg/kg, from 30 mg/kg previously. The batch-level cap of 80 mg/kg, origin