Optional Reduced NOx Emission Standards for On-Road Heavy-duty Engines

This page last reviewed December 9, 2013


option nox picture California Air Resources Board (ARB) staff is now seeking input on developing optional low oxides of nitrogen (NOx) emission standards for on-road heavy-duty engines. ARB staff would like to encourage engine manufacturers to introduce new technologies to reduce NOx emissions below the current mandatory on-road heavy-duty diesel engine emission standards for model years 2010 and later. California’s current emission standards for heavy-duty engines are contained in California Code of Regulations, Title 13, section 1956.8. It is envisioned that the proposed optional low NOx standards would encourage engine manufacturers to showcase new technologies and could be utilized to prioritize funding in incentive programs such as the Carl Moyer Memorial Air Quality Standards Attainment Program. Staff plans to propose new optional low NOx standards for on-road heavy-duty engines to the Board in late 2013.

What's New

Posted December 5, 2013:

Public hearing announced. The Air Resources Board will conduct a public hearing on December 12, 2013, in Sacramento, to consider five heavy-duty vehicle related proposals, including adopting the next generation of optional reduced NOx emission standards for on-road heavy-duty engines. The public hearing notice and staff report have been posted on the draft proposed regulations web page. ARB staff has posted additional background materials, calculations, and models to allow stakeholders to evaluate the emission and cost estimates presented.

Posted March 8, 2013:

The Optional Low NOx standards presentation for the public workshop in Sacramento on March 11, 2013, has been posted.

Posted February 14, 2013:

ARB invites you to participate in a public workshop on March 11, 2013, in Sacramento to discuss proposed optional low NOx diesel engine emission standards for on-road heavy-duty diesel engines. More information about this workshop can be found in this mailout.


Monday, March 11, 2013


8:30 a.m. – 4:00 p.m.


Air Resources Board
Coastal Hearing Room
1001 I Street
Sacramento, California 95814


For more information, please contact Mr. Todd Sterling, Air Pollution Specialist, at (916) 323-2397 or Ms. Kim Heroy‑Rogalski, Manager, at (916) 327-2200.