CA Health & Safety Code Section 44299.79

On or before January 10, 2001, the executive officer of the state board shall make a determination as to the eligibility of NOx retrofit technologies for use in the program, and may make additional determinations of eligibility of NOx technologies after January 10, 2001. In order to be determined eligible by the executive officer of the state board, each NOx retrofit technology shall have, at a minimum, the ability to reduce onroad heavy-duty diesel emissions of NOx by 10 percent or more and shall be durable and effective in reducing emissions, as determined by the executive officer of the state board.