Comment submitted by Environmental Protection Network (EPN)

Summary: The Environmental Protection Network (EPN) opposes the EPA's proposal to delay the Tier 4 criteria pollutant standards for light-duty and medium-duty vehicles. They argue that the EPA's justification for the delay is based on speculative assertions rather than concrete evidence, and that the agency already possesses the necessary in-house data to determine that manufacturers are capable of complying by model year 2027.