Commission hears experts and staff on diesel emissions testing; no immediate mandate set

The Utah County Commission held a work session on diesel emissions testing and heard presentations from the Healthy Environment Alliance of Utah (HEAL), county health staff, and vehicle‑emissions program managers about the merits, technical limits, and equity questions of expanded diesel testing.

Ashley Sotishek, policy director for HEAL, said diesel testing began in Utah County in 1994 and ran until 2006; she urged reconsideration because diesel vehicles can produce high particulate emissions that harm public health and because local diesel penetration (about 5–6% of registered vehicles) is higher here than the national average. She described newer testing methods that rely on onboard diagnostics (OBD) for post‑2008 vehicles and said Weber County recently expanded its program to include diesel vehicles, citing an environmental‑quality advisory committee analysis that diesel vehicles contributed a disproportionate share of on‑road NOx in that county.

County health staff (Ralph Clegg) and the vehicle emissions program manager (Dana Kindiff) explained technical limitations: older diesel vehicles lack robust OBD monitoring, diesel OBD implementations are still maturing and have shown “deficiencies” in laboratory analyses, and vehicle tampering (aftermarket chips or component removal) can defeat station tests. Kindiff described operational experience from the county’s earlier diesel program (1994–2006), noting that most problematic vehicles were medium‑duty/light‑duty diesels (up to 14,000 pounds) rather than long‑haul semis. He said the health department currently investigates complaint‑driven “smoking vehicle” reports and can escalate repeat offenders to mandatory testing.

Commissioners and staff pressed for clearer evidence that a diesel testing program would deliver measurable county‑level air‑quality improvements and whether the Environmental Protection Agency would grant State Implementation Plan credit for diesel testing (staff said EPA credit historically has not been available for diesel testing). Several commissioners raised fairness and cost concerns for diesel vehicle owners and emphasized the need for targeted enforcement of tampered or visibly smoking vehicles.

The health department said it is not opposed to diesel testing in principle but recommended choosing an approach that avoids known loopholes and ensures effectiveness; Mountainland Association of Governments staff noted absence of EPA‑accepted studies proving diesel testing yields measurable county‑level improvements, and urged the commission to weigh costs and crediting before adopting a program. Commissioners requested follow‑up information and suggested further technical briefings before policy direction or a formal program was adopted.