CARBThe California Air Resources Board (CARB) last week, on Nov. 3, held its Public Rulemaking Workshop Regarding Tier 5 Amendments for Diesel Off-Road Emission Standards, detailing the objectives, strategy and tactics needed for attainment of Federal National Ambient Air Quality Standards (NAAQS). During the five-hour workshop, CARB staff outlined various proposals intended to meet these goals:

  1. Lower criteria pollutant and greenhouse gas (GHG) emission standards
  2. New low load cycle (LLC) certification
  3. Promulgation of emissions credits for hybrid powertrain and zero-emission engines
  4. Increase in the useful life standards for off-road equipment
  5. Extension of minimum warranty periods
  6. Restrictions on prolonged idling
  7. Development of onboard diagnostic requirements
  8. Implementing a manufacturer-run off-road in-use testing program

One of the primary goals of these regulations is the reduction of criteria pollutant emissions, primarily the oxides of nitrogen (NOx) and particulate matter (PM). CARB is looking to achieve NOx standards up to 90% more stringent, and PM standards up to 75% more stringent than todays Tier 4 standards. These emissions reductions are likely to impact all power categories, including those that do not currently utilize exhaust after treatment, such as diesel particulate filters (DPFs) and selective catalyst reduction (SCR). CARB staff intends on introducing this regulation to the Board for approval in 2024, with an implementation start date of 2028. 

This rulemaking effort joins a host of other CARB led programs initiated in California that effects the off-road heavy duty equipment industry as they work to meet California Gov. Gavin Newsom’s Climate Change executive order, N-79-20.

Some of these programs include:

  1. The Small Off-Road Engines (SORE) Zero-Emissions regulation
  2. Clean Off-Road Equipment (CORE) Construction Funding
  3. Zero-Emission Industrial Forklift regulation
  4. In-Use Off-Road Diesel Fleet Requirements
  5. The Targeted Manufacturer Rule

Newsome aspires to influence climate change policy on a global level, leading to new rulemakings with expansive scopes and extremely aggressive timelines. As a key stakeholder, the off-road heavy duty equipment industry must stay engaged during these rulemaking efforts to ensure policy decisions are based on sound science and realistic implementation timetables. AEM is determined to provide an industry voice in these discussions to ensure our members stay informed and up-to-date.

To learn more, or to stay engaged, please contact AEM Director of Global Standards and Compliance Jason Malcore at

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