Comment submitted by Timothy Cole

I am Timothy Cole with PPEI Tuning. I support postponing Tier 4 but urge EPA to reconsider Tier 3 and 4 standards. Most emission reductions happened under Tier 2, while later tiers brought far higher costs for little gain. EPA should (1) keep the Tier 4 postponement, (2) revert to Tier 2 standards, and (3) create a technology-neutral safe harbor for vehicles meeting Tier 2 emissions. My reasons are below: 1) Emission standards impose costs on all Americans, especially disadvantaged groups. These communities face health challenges and higher living costs from compliance. Real benefits should matter more than model projections. 2) The costs of Tiers 3 and 4 outweigh their benefits. By Tier 2, about 95% of emissions had been cut, with only minor additional reductions since. Achieving these small gains costs about $195 billion per year—expenses passed to businesses and consumers. Required after-treatment systems since 2007.5 have cost the nation $3.6 trillion from 2008 to 2026. The Clean Air Act requires EPA to weigh costs, energy, and safety when setting standards, using benefit-cost analyses to ensure benefits exceed costs. In January 2026, EPA stopped assigning dollar values to PM₂.₅- and ozone-related health benefits, citing lack of confidence in the models. Previously, these benefits made up most of the monetized justification for air regulations. This shift is significant. Monetized health benefits formed up to 94% of EPA’s justification for major standards, like the 2007 Diesel Rule ($70B in benefits vs. $4.2B costs) and Tier 3 ($7.4–$19B benefits vs. $1.5B costs). Now, EPA does not assign a dollar value to these benefits, undermining the economic justification for more stringent standards. The 2007 Heavy-Duty Diesel Rule and Tier 3 Rule, once justified by tens of billions in annual monetized benefits, now rest on a methodology that assigns zero dollar value to the most important benefits. In effect, the main economic justification for ever-stricter standards has disappeared under EPA’s new analytical framework. The costs remain real and ongoing, impacting farmers, truckers, small businesses, and consumers through higher prices, maintenance costs, downtime, and reduced equipment life. Over $3.6 trillion in costs since 2008 averages more than $27,000 per household—real, not projected, costs. The contrast is stark: EPA’s original justification was tens of billions in annual benefits, but now those benefits are valued at zero while costs surpass $3.6 trillion. Given the Clean Air Act’s requirement to weigh costs, energy, and safety, the balance has fundamentally shifted now that benefits are valued at zero and costs have reached $3.6 trillion. With benefits now assigned a value of zero and costs so high, there is no longer an economic basis to justify standards beyond Tier 2. EPA should address this before adding more costs. I urge EPA to keep the Tier 4 postponement, revert to Tier 2, and create a safe harbor for vehicles at Tier 2 emissions. Benefit-cost analysis should reflect these realities and support balanced, evidence-based standards. Federal law requires feasible standards with justified costs and minimal harm to small businesses. EPA lacks a basis for imposing such heavy burdens. These costs, about 0.6% of GDP, fall on small businesses, shippers, and consumers through higher logistics expenses. EPA should revert to Tier 2. 3) EPA should adopt a safe harbor under Clean Air Act §203(a), letting owners use technology-neutral alternatives achieving Tier 2-equivalent emissions, supported by documented testing. This safe harbor would be technology-neutral, not mandating specific hardware but allowing for cost-effective, innovative solutions tailored to real-world needs. I am ready to provide data and testimony and join any EPA working group on Tier 4. 4) EPA has clear statutory authority to revisit standards that no longer achieve the required balance of costs, energy, and safety under the Clean Air Act, especially given higher-than-expected real-world costs and marginal additional benefits. For these reasons, EPA should keep the Tier 4 delay, restore Tier 2 standards, and adopt a technology-neutral safe harbor. This would bring relief while maintaining air quality gains. Thank you for considering these recommendations. Sincerely, Chad Cole