Comment submitted by Justin Granger

I am Justin Granger, and I oversee sales and dealer support for PPEI. I support the EPA’s proposal to postpone Tier 4 implementation. However, I recommend the Agency go further and re-evaluate whether Tier 3 and Tier 4 standards remain justified under Clean Air Act § 202(a). EPA’s own historical analyses show that the vast majority of targeted NOx and particulate reductions were achieved under Tier 2. Subsequent tiers have delivered only marginal incremental benefits while imposing disproportionately high compliance and maintenance costs. EPA should therefore (1) retain the Tier 4 postponement, (2) initiate rulemaking to revert to Tier 2 standards, and (3) establish a technology-neutral safe harbor for in-use vehicles that can demonstrate Tier 2-equivalent emissions performance. Here is why: 1. Every life matters—not just those affected by respiratory conditions. Focusing exclusively on one set of health outcomes while ignoring broader societal impacts is shortsighted. When trillions of dollars in compliance costs are passed through the economy, all Americans suffer—especially low-income communities through higher food prices, reduced economic opportunity, shuttered small businesses, and lost livelihoods. Honest policy requires weighing both sides of the ledger. Real harm to real people today matter more than modeled statistical benefits. 2. The benefits of Tiers 3 and 4 do not justify their costs. EPA’s Regulatory Impact Analyses demonstrate clear diminishing returns. By the end of Tier 2, roughly 95% of the targeted NOx and PM reductions from pre-Tier 2 levels had already been achieved. With Tier 3 largely phased in, the fleet is now approximately 98% effective on those same pollutants. The incremental benefit of further tightening beyond Tier 2 is therefore only about 3% of the original target—at enormous additional cost. After-treatment systems (DPF, SCR, DEF, etc.) mandated since the 2007.5 model year have generated massive ongoing expenses. According to the U.S. Small Business Administration Office of Advocacy, these systems impose roughly $19.5 billion in annual compliance, repair, and operational costs. Over 18.5 years (2008–mid-2026), this totals more than $360.75 billion. Importantly, in January 2026 the EPA discontinued the monetization of PM₂.₅- and ozone-related health benefits—the very category that previously accounted for the vast majority (often 84–94%) of projected monetized benefits in major diesel and vehicle emissions rules. Under the Agency’s current methodology, the primary economic justification for these stringent standards has effectively disappeared, while the real-world costs remain. The Clean Air Act requires EPA to consider costs, energy, and safety when setting standards. That balance now clearly favors reversion to Tier 2. 3. Technology-Neutral Safe Harbor for In-Use Vehicles I respectfully request that EPA adopt a bright-line safe harbor under its authority to interpret and enforce Clean Air Act § 203(a). Specifically, owners and operators of in-use motor vehicles and nonroad equipment should be permitted to remove or render inoperative Tier 3 or Tier 4 emissions devices provided they replace them with technology-neutral solutions that achieve emissions performance equal to or better than Tier 2 levels. Compliance would be supported by documented engineering analysis, test data, or third-party verification. This approach would be explicitly technology-neutral, encouraging innovation in lower-cost, more durable solutions rather than mandating specific OEM hardware. 4. Clear Statutory Authority Clean Air Act § 202(a)(1) directs the Administrator to prescribe and, from time to time, revise emissions standards after giving appropriate consideration to cost, energy, and safety factors. Given higher-than-expected real-world costs, marginal additional environmental benefits, and the EPA’s updated benefit-cost methodology, there has never been a stronger basis for revisiting these standards. For these reasons, I urge the EPA to retain the Tier 4 delay, initiate rulemaking to restore Tier 2 criteria-pollutant standards, and adopt the proposed technology-neutral safe harbor. These actions would deliver meaningful regulatory relief while preserving the substantial air-quality gains already achieved. I stand ready to provide real-world data, duty-cycle profiles, cost analyses, and fleet-operator perspectives to support this approach, and I welcome the opportunity to participate in any pre-NPRM working groups or listening sessions. Hoping for your better judgement moving forward - Justin Granger