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Staff Presentations & Recorded Webcast Now Available

California Air Resources Board (CARB) staff has posted the workshop webcast and the presentation containing the backup slides that were used to address stakeholder comments.

Presentation

View Recording

Staff is requesting comments on the draft Proposed Regulation Order and both presentations by November 18, 2024.

Background

Currently, CARB’s regulations for new off-road diesel engines are largely harmonized with the United States Environmental Protection Agency’s for non-road diesel engines. Off-road and non-road refer to the same type of engine or equipment. The engines in this sector are land-based and range from less than 19 kilowatts (kW) to well over 560 kW in rated power. The existing Tier 4 emission standards were adopted in 2004 and were based on the capabilities of the best available technologies at that time: diesel particulate filters and selective catalytic reduction. As of model year 2020, more than half of all new off-road compression-ignition engine families continue to be certified in California to the Tier 4 final emission standards without diesel particulate filters. Exhaust aftertreatment technology has matured significantly in the last 20 years. Significant reductions in Particulate Matter (PM) and Nitrogen Oxides (NO_x) are now feasible beyond the current Tier 4 standards of 0.02 grams per kilowatt-hour (g/kW hr) and 0.40 g/kW-hr for 56 - 560 kW engines, respectively.

CARB staff are working on amendments to the current Tier 4 off-road new diesel engine standards. Staff are proposing more stringent exhaust emission standards for NO_x (up to 90% more stringent) and PM (up to 75% more stringent) than today’s Tier 4 standards. First-time tailpipe CO₂ emission standards and OBD requirements for off-road engines are being proposed. CARB staff are proposing enhanced in-use compliance testing, more representative useful life periods, and a new low-load test cycle. CARB staff’s proposal is scheduled for Board consideration in late 2025, with implementation beginning as early as the 2029 model year.

CARB is currently contracting with the Southwest Research Institute to investigate the feasibility of standards lower than Tier 4 standards. The Southwest Research Institute is demonstrating the feasibility of lower NO_x and PM, and new CO₂ emission standards.

This workshop was the eighth public event in CARB’s Tier 5 rulemaking. CARB staff invites industry, fleet owners, trade associations, representatives of non-governmental organizations, environmental groups, air districts, and other interested stakeholders to participate and provide feedback on the Draft Proposed Regulation Order for the Tier 5 rulemaking.

Contact

If you have questions, please contact the Tier 5 rulemaking section.

If you require a special accommodation or need this document in another language or in an alternate format (i.e., Braille, large print), please contact Isabel Guerra as soon as possible. TTY/TDD/Speech to Speech users may dial 711 for the California Relay Service.

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CARB is the lead agency for California’s fight against climate change, and oversees all air pollution control efforts in the state to attain and maintain health-based air quality standards.

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