Mexico: Heavy-duty: Emissions
- 1 Overview
- 2 History
- 3 Technical Standards
- 4 Links
- Standard type: Conventional pollution emissions
- Regulating body: Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT)
- Current standard: NOM-044-SEMARNAT-2006 for diesel engines and NOM-076-SEMARNAT-2012 for engines that run on gasoline, liquified petroleum gas (LPG), and natural gas
- Applicability: (GVW) > 3,857 kg
A proposed modification to existing heavy-duty vehicle emissions standards was published on December 17, 2014 in the federal diary. The 60-day public comment period has closed and publication of the final standards is expected in 2015.
Emissions standards for both light- and heavy-duty vehicles were first established in 1988 and became effective in model year 1993 (NOM-044-ECOL-1993). The standard NOM-044-SEMARNAT-2006 was adopted in 2006 as an update to NOM-044-SEMARNAT-1993, and it establishes emission limits for total hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particles, and opacity for new heavy-duty diesel engines. The standard allows compliance with either US 2004 or Euro IV equivalent standards. NOM-076-SEMARNAT-2012, was adopted on 27 November 2012 and establishes emissions for hydrocarbons, nitrogen oxides and carbon monoxide and evaporative emission limits for hydrocarbons for new heavy-duty engines that use gasoline, liquid petroleum gas (LPG), natural gas or other alternative fuels.
Mandatory compliance with EPA 2004/Euro IV standards began in July 2008, however, the relevant standard was modified in 2011 by an Acuerdo (agreement) from SEMARNAT to extend the regulatory timeline for compliance with EPA 2004/Euro IV standards to June 2014.
3 Technical Standards
Both NOM-044-SEMARNAT-2006 (diesel) and NOM-076-SEMARNAT-2012 (gasoline) are applicable to new engines intended for use in vehicles with a gross vehicle weight greater than 3,857 kg (8,500 lbs.) or for new vehicles of this size.
3.1 Diesel Engine Standards
Emission standards for new heavy-duty diesel engines first became effective in model year 1993 and were based on US 1991 and later requirements, including the US Environmental Protection Agency (EPA) FTP transient test cycle. Standards for MY 1993-1998 were equivalent to US standards and compliance could be demonstrated through certification by US EPA. Under NOM-044, engines in Mexico are provided compliance options and can meet European standards, as measured on the official European test cycles (ETC and ESC), as an alternative to the EPA-based standards; compliance with standards can be demonstrated through:
- Letter or proof issued by motor manufacturer, including earnings report issued by the testing laboratory,
- Certificate or proof issued by the Environmental Protection Authority of the country of origin or country of certification, or
- Certificate issued by Certification Bodies for the country of origin or country of certification.
In 2006, the standard NOM-044-SEMARNAT-2006 was adopted as an update to NOM-044-ECOL-1993. It establishes emission limits for total hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particles, and opacity for new heavy-duty diesel engines. The standard allows compliance with either US 2004 or Euro IV equivalent standards. The emission standards compliance timeline and current equivalent limit values of the 1993 and 2006 standards are outlined below:
|1993||US EPA 1991|
|1994||US EPA 1994|
|1998||US EPA 1998|
|2006-2008||US EPA 1998 or Euro III|
|2008†||US EPA 2004 or Euro IV|
† extended through 2014.06; later requirements are not specified.
|Smoke opacity %
|Smoke opacity % |
|Standard||Test Method||HC||NMHC||CO||NOx||Part||Smoke Opacity3|
A proposed modification to existing heavy-duty vehicle emissions standards was published on December 17, 2014 in the federal diary. The 60-day public comment period closed in March 2015. Publication of the final standards has been delayed but is expected in 2016.
The proposed regulation will still apply to diesel engines or full vehicles with a gross vehicle weight above 3,857 kg. The following table shows the timing and certification requirements of the proposed standard. Standard A, in force from the adoption of the proposal through 2017, is essentially the same as the current NOM-044 standard; starting in 2018, Standard B requires compliance with either Euro VI/6 or EPA 2010 standards.
|Timeframe||NOM-044 Standard||Certification Requirement|
|Beginning Jan. 1, 2018||1B||EPA 2010|
22.214.171.124 Limit values
Limit values for heavy-duty engines are shown in the following tables. Limits are set in grams per brake horsepower-hour (g/bhp-hr) for EPA 2004 and EPA 2010 standards, and are in grams per kilowatt-hour (g/kWh) for Euro IV and Euro VI standards. Particle number and ammonia (NH3) limits are set as part of the Euro VI standards but have not been defined as limit values under EPA standards.
|Certification Requirement||Standard||Test Method||CO||NOx||NMHC||HCNM + NOx||PM|| Particle Number
|EPA 2004||1A||SET & FTP||15.5||–||–||2.4||0.10||–||–|
|EPA 2010||1B||SET & FTP||15.5||0.20||0.14||–||0.01||–||–|
|Certification Requirement||Standard||Test Method||CO||NOx||NMHC||HC||PM|| Particle Number
|Euro VI||2B||WHSC||1.5||0.4||–||0.13||0.01||8.0 x 1011||10|
|WHTC||4.0||0.46||–||0.16||0.01||6.0 x 1011||10|
Useful life is defined as the reference values (measured in vehicle-km and years) that are used in durability tests for new engine or vehicle certification. Useful life does not refer to in-use vehicle emissions, nor is it equivalent to the manufacturer warranty.
|Certification Requirement||Standard|| Gross Vehicle
|Distance (km)||Time (years)|
| EPA 2004 &
|1A & 1B||3,857 - 8,845||177,023||10|
|8,846 - 14,970||297,721|
|14,971 and larger||700,046|
|Euro IV||2A||3,857 - 15,999||200,000||6|
|16,000 and larger||500,000||7|
|Euro VI||2B||3,857 - 15,999||300,000||6|
|16,000 and larger||700,000||7|
The proposed standard includes optional alternative certification limits for medium-duty complete vehicles starting in 2018. The 2015-2017 standards do not include options for complete vehicle certification because these options are only available in the EPA 2010 and Euro VI standards. The following tables includes the optional pathways for certification of complete vehicles.
|Certification Option||Standard|| Gross Vehicle
|Test Cycle||CO||NOx||NMHC||PM|| Particle Number
|EPA 2010||3B||3,857 - 4,539||FTP 75||–||0.124||0.121||0.012||–||177,023||10|
|4,540 - 6,350||–||0.249||0.143||0.012||–|
|Certification Option||Standard|| Reference
|Test Cycle||CO||NOx||HC + NOx||PM|| Particle Number
|Euro 6||4B||≤ 2,840||NEDC||0.74||0.125||0.215||0.005||6.0 x 1011||160,000||5|
The 3B pathway was introduced because EPA 2010 standards provide an option to certify vehicles with a gross vehicle weight rating (GVWR) of less than 6,350 kg as complete vehicles on a chassis dynamometer, using the same FTP 75 drive test cycle that is used for light-duty emissions standards. The g/km limit values included in the proposal are taken directly from EPA 2010 heavy-duty emissions standards. The 4B pathway was introduced due to a change in metrics for weight ratings in Euro VI standards for heavy-duty vehicles and Euro 5 and 6 standards for light-duty vehicles. The previous European standards had defined heavy-duty vehicles as having a technically permissible maximum laden mass greater than 3.5 tons, whereas the new standards define heavy-duty vehicles according to their reference, or unloaded, mass. This change means that some vehicles sold will have a GVWR higher than 3,857 kg but a reference mass below the 2,610 kg cut-off under European standards. These vehicles would then be subject to light-duty Euro 6 standards in the EU, rather than heavy-duty Euro VI standards. In order to ensure that any vehicle certified to Euro 6 standards could be sold in Mexico, the proposed standard makes complete vehicle certification an option for all vehicles with a reference mass less than or equal to 2,840 kg, the maximum allowable under light-duty Euro 6 standards.
126.96.36.199 On-Board Diagnostics and Compliance Inducements
The proposed standards require the installation and operation of full On-Board Diagnostic (OBD) systems on all new vehicles. The type of OBD system must be recorded in the certification documentation. Appendix B of the proposal provides a detailed explanation of the general system requirements and attendant documentation. As both EPA and Euro standards require the full phase-in of OBD systems before 2018, the proposal relies on certification documentation as the primary proof of compliance with OBD requirements. Similarly, the proposal requires that new vehicles and engines that use a reagent for NOx-reducing SCR systems are also equipped with operating alerts and driver inducements to ensure the correct functioning of these systems. These failsafes include lights, auditory alarms and requirements to safely limit vehicle operation in the case of improper use, such as poor quality diesel exhaust fluid (DEF) or insufficient DEF supply. Appendix C provides a detailed explanation of the system requirements and attendant documentation.
188.8.131.52 Provisional Limitations
The proposal includes five transitorios, or provisional limitations to the standard. The first two and the final provisions are common limitations, specifying that the standard comes into force 60 days after publication, that it replaces the existing NOM-044 standard, and that currently valid certificates issued under the existing standard will be valid until the application of the B standards established under the new proposal. Two additional provisions are more unique to this proposal. The third provision states that in January 2017, SEMARNAT will evaluate the national availability of ultralow-sulfur diesel in order to determine if the conditions exist for compliance with the B standards. In the case that availability is insufficient, the Secretary will delay the entry into force of the B standards by 12 months. The fourth provision allows manufacturers to sell existing inventories of vehicles that were produced during the application of standard A for up to six months after the implementation of standard B. The intent is to provide a reasonable period of transition while protecting against stockpiling of old inventory.
3.2 Gasoline, LPG, and NG Engine Standards
Emission standards for new heavy-duty engines fueled by gasoline, LPG, natural gas and other alternative fuels are specified by the NOM-076 standard, adopted in 1995, with later amendments in 2012. Similar to the diesel regulations, the emission standards are applicable to gas engines used in vehicles of GVW > 3,857 kg (8,500 lbs).
Gasoline and gaseous fueled engines are tested over the FTP transient test and must meet the US EPA-based emission standards shown in the following 2 tables.
|A1||3,857kg ≤ GVW ≤ 6,350kg||1.1||N/A||14.4||4.0||3.0|
|B2||3,857kg ≤ GVW ≤ 6,350kg||N/A||0.14||14.4||0.2||1.75|
Natural gas engines can alternatively be tested over the European Transition Cycle; relevant standards are show in the following table.
Manufacturers may choose to certify gasoline and gaseous fueled vehicles with GVW up to 6,356 kg (14,000 lbs) on a chassis dynamometer over the FTP-75 cycle. The table below summarizes emission standards for chassis-certified vehicles.
|A||3,857 - 4,536 kg||0.285||3.418||0.807||3.0|
|4,537 - 6,356 kg||0.372||4.350||1.243||3.0|
|B||3,857 - 4,536 kg||0.121||3.977||0.124||1.75|
|4,537 - 6,356 kg||0.142||4.536||0.248||2.30|
4.1 Regulatory Documents
- Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT)
- ICCT policy update: NOM-044 Proposed Rule