NATSO and SIGMA challenge proposed EPA changes to diesel exhaust rules

The EPA’s latest proposal seeks to strip away mandatory deratement as an inducement for NOx emissions compliance starting in Model Year 2029. NATSO and SIGMA contend that this shift undermines ongoing efforts from the previous administration, which introduced critical software updates and sensor adjustments in 2025 and early 2026. These measures were designed to reduce false engine warnings and prevent the unnecessary removal of functional trucks from service.

David Fialkov, head of government affairs for the groups, emphasized that the industry needs more time to realize the benefits of the current framework. He warned that the EPA's impatience risks creating consumer confusion and driving up costs for essential exhaust fluids. Because original equipment manufacturers have deeply integrated Selective Catalytic Reduction technology into their engine designs to meet emissions targets, the groups believe that removing regulatory pressure now would be counter-productive.

NATSO and SIGMA maintain that diesel exhaust fluid remains a cornerstone of environmental progress in the trucking sector. They are calling for future reform efforts to be strictly evidence-based to ensure that availability and affordability remain stable for operators across the country.