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The United States Environmental Protection Agency (“EPA”) on January 6th issued a pre-publication Advance Notice of Proposed Rule (“ANPR”) addressing the Clean Air Act Heavy-Duty Engine Standards.

The ANPR also describes the agency’s interest in streamlining and improving certification procedures to reduce costs for engine manufacturers.

The ANPR is a part of the EPA’s Cleaner Trucks Initiative (“CTI”). The CTI includes new emission standards for oxides of nitrogen (NOx) and other pollutants for highway-heavy engines.

Title II of the Clean Air Act provides EPA the statutory authority to promulgate standards for mobile sources. Mobile sources include heavy duty-vehicles. They are a significant contributor to mobile source emissions of NOx.

Section 202(a)(1) of the Clean Air Act requires that the EPA set emission standards for air pollutants, including NOx from new motor vehicles or new motor vehicle engines, which the agency finds causes air pollution that may endanger public health or welfare. Under Section 202(a)(3)(A) of the Clean Air Act, NOx (and certain other) emission standards for heavy-duty vehicles and engines are to “reflect the greatest degree of emission reduction achievable through the application of technology which EPA determines will be available for a model year to which such standards apply. Such technology must consider costs, energy, and safety factors associated with the application of such technology.

EPA last revised NOx standards for on-highway heavy-duty trucks and engines in 2001. The agency believes there is an opportunity to modernize the requirements to reflect the capability of available emissions control technology. Identified for particular attention are emission controls under low-load conditions. Such conditions include truck:

• Idling;
• Moving slowly;
• Stop-and-go traffic.

Various organizations such as the Environmental Defense Fund petitioned the EPA in 2016 to develop more stringent NOx emission standards for on-road heavy-duty engines. EPA states it subsequently met with a wide range of stakeholders and that some consensus existed for aligning implementation of new NOx standards with existing milestones for greenhouse gas standards.

In determining the appropriate level and form of the future NOx standards, the EPA states in the ANPR that key components include:

• NOx emission standards;
• Improvements to test procedures and test cycles to ensure emission reductions occur in the real world, not only over the currently applicable certification test cycles;
• Updated certification and in-use testing protocol;
• Longer periods of mandatory emissions-related component warranties;
• Consideration of longer regulatory useful life, reflecting actual in-use activity;
• Consideration of rebuilding;
• Incentives to encourage the transition to current-and next-generation cleaner technologies as soon as possible.

A link to the ANPR can be found here.