N.J. Stat. § 39:8-61
The Department of Environmental Protection, in consultation with the commission and the Department of Transportation, shall adopt rules and regulations pursuant to the "Administrative Procedure Act," P.L. 1968, c.410 (C.52:14B-1 et seq.) establishing exhaust emissions standards and test methods, and standards for emission control apparatus and related items, in accordance with P.L. 1966, c.16 (C.26:2C-8.1 et seq.) or as may be authorized or provided otherwise by federal law, rule or regulation, for diesel buses, heavy-duty diesel trucks, and other diesel-powered motor vehicles. The test methods shall be accurate, objective, and capable of being performed routinely in the periodic inspection program and the roadside enforcement program. In adopting such standards and test methods, the Department of Environmental Protection may consider, but need not necessarily adopt, exhaust control technology current at the time of adoption of the rules and regulations, as well as guidance, standards, directives, and other information issued by the EPA, any other state, or any governmental agency, scientific research entity, or industry. The Department of Environmental Protection may provide that the standards and test methods vary according to the age of the vehicle or according to other relevant factors, and the department may provide exemptions based upon good cause, including, but not limited to, whether the vehicle has been tested within the previous six months or other reasonable period of time in accordance with the law of another state or jurisdiction and has been found to be in compliance with the exhaust emissions standards of the state or jurisdiction in which the vehicle was tested. The provisions of this act shall not apply to any heavy-duty diesel truck or other diesel-powered motor vehicle owned and operated by a county, municipality, fire district, or duly incorporated nonprofit organization for first aid, emergency, ambulance, rescue, or fire-fighting purposes.
N.J.S. § 39:8-61