[Code of Federal Regulations] [Title 40, Volume 18] [Revised as of July 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR89.106] [Page 49] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 89--CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES--Table of Contents Subpart B--Emission Standards and Certification Provisions Sec. 89.106 Prohibited controls. (a) An engine may not be equipped with an emission control system for the purpose of complying with emission standards if such system will cause or contribute to an unreasonable risk to public health, welfare, or safety in its operation or function. (b) You may not design your engines with emission-control devices, systems, or elements of design that cause or contribute to an unreasonable risk to public health, welfare, or safety while operating. For example, this would apply if the engine emits a noxious or toxic substance it would otherwise not emit that contributes to such an unreasonable risk. [59 FR 31335, June 17, 1994. Redesignated at 63 FR 56995, Oct. 23, 1998; 67 FR 68339, Nov. 8, 2002]