For decades, the EPA has shaped emissions standards to tackle the pollution created by diesel engines, which power everything from trucks to construction equipment. This article delves into the evolution of Tier 1 through Tier 4 standards, the Energy Policy Act's initiatives, and state-specific regulations like California’s CARB standards. Discover how to meet compliance, whether through retrofitting, cleaner technology, or alternative registration options like Montana LLCs, to help diesel vehicle owners work within these regulations while considering their impact on air quality and public health.