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Controlling Air Pollution from Motor Vehicles

One-time fleet reports associated with the Advanced Clean Trucks one-time reporting requirement are due from applicable fleets by April 1, 2023. Additional information and the Final Reporting Form (Excel), which must be used by fleet owners for their official fleet reporting, are available on the Heavy-Duty Vehicles webpage. Questions may be submitted to

DEC held a webinar on September 13, 2022, to provide an overview of the Advanced Clean Trucks reporting template and accompanying guidance and to accept feedback from applicable entities.

DEC held a webinar on September 16, 2022, regarding its evaluation of potential adoption of the California Advanced Clean Cars II (ACC II) regulation. DEC staff provided relevant policy background and an overview the ACC II regulation. The slide presentation is available as a downloadable PDF.

DEC held a webinar on September 28, 2022, regarding its evaluation of potential adoption of the California Heavy-Duty Low NOx Omnibus and California Phase 2 Greenhouse Gas Standards regulations. DEC staff provided relevant policy background and an overview the California Heavy-Duty Low NOx Omnibus and California Phase 2 Greenhouse Gas Standards regulations. The slide presentation is available as a downloadable PDF.

DEC held a webinar on September 29, 2022, regarding potential proposed revisions to Subpart 217-5, Heavy Duty Inspection and Maintenance Program (leaves DEC website), to reflect revised Heavy-Duty Diesel Vehicle Inspection and Maintenance Program ("HDDV I/M") requirements. DEC staff provided relevant policy background and an overview of the potential proposed revisions to Subpart 217-5 and an overview of the revised HDDV I/M requirements. The slide presentation is available as a downloadable PDF.

Cars, trucks, buses, off-road vehicles and planes are all considered mobile sources of air pollution. To reduce air pollution from these significant sources, as required by the federal Clean Air Act of 1990, DEC:

How Engine Pollution Harms the Environment and Health

Carbon monoxide, nitrogen oxides, and hydrocarbons are released when fuel burns in an internal combustion engine. They may also be released when vehicle tailpipes emit air and fuel residuals. Gasoline vapors also escape into the atmosphere during refueling and when fuel vaporizes from engines and fuel systems caused by vehicle operation or hot weather.

The pollutants in engine emissions from vehicles and lawn equipment cause damage to lung tissue and can lead to and aggravate respiratory diseases, such as asthma. Motor vehicle pollution also contributes to the formation of acid rain. The pollution also emits greenhouse gases that cause climate change.

Diesel engines are durable and efficient. However, because they consume diesel fuel, a complicated mix of petroleum components, they produce some pollutants. A small amount of the fuel exits the engine unburned. These airborne hydrocarbons can form larger particles in the atmosphere when they contact airborne dust and other particles.

Unlike gasoline engines, which may not get enough air into the cylinder for combustion, diesel engines operate with excess air so emissions of carbon monoxide are very low, though still measurable. Carbon monoxide is a colorless, odorless gas that combines with blood and limits its ability to transport oxygen. Since the engines are consuming fuel and air and create heat in the combustion process, nitrogen from the air can be transformed into nitrogen oxides which are reddish brown gases that irritate the lungs and eyes.

Pollutants emitted directly from vehicles are not the only cause for concern. On warm, sunny days, hydrocarbons react with oxides of nitrogen to create a secondary pollutant, ozone. In many urban areas, motor vehicles are the single largest contributor to ground-level ozone which is a common component of smog.

Zero-Emission Vehicles (ZEV)

ZEVs include battery-electric vehicles, plug-in hybrid-electric vehicles, and hydrogen fuel-cell-electric vehicles. These technologies can be used in passenger cars, trucks and transit buses. The federal Clean Air Act allows New York State to adopt California's zero emission vehicle (ZEV) standards.

New York and seven other states joined together in an initiative to put 3.3 million ZEVs on the road by 2025. A Memorandum of Understanding outlines the steps these states will take to expand consumer awareness and demand for ZEVs. A Multi-State Zero-Emission Vehicle Action Plan for 2018-2021 (leaves DEC website) outlines the next steps these states will take to grow consumer awareness and demand for ZEVs.

Reducing Vehicle Pollution

The State programs for reducing air pollution from vehicles include:

  • supporting the manufacture and sale of zero and low emission vehicles;
  • selling modified fuels (oxygenated fuels in some parts of the state, reformulated gasoline in and near NYC, less-volatile fuels across the State in the warmer months, and low-sulfur diesel fuel);
  • requiring special equipment at gas pumps, such as special nozzles that recover vapors instead of releasing them into the air;
  • a statewide enhanced inspection and maintenance program.

Motorists can significantly reduce pollution by following tips on Living the Green Life.

DEC Commissioner Seggos' Testimony to EPA Regarding Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule Part One (PDF) - June 2, 2021.

Catalytic Converters

On December 14, 2022, DEC held a stakeholder outreach meeting to discuss the prohibition of federal aftermarket catalytic converters, effective January 1, 2023. View the slide presentation (PDF).

A catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from motor vehicle engines into less-toxic pollutants by catalyzing a redox reaction (an oxidation and a reduction reaction). Catalytic converters are used with gasoline and diesel-powered engines.

A repair shop may identify the need to replace the catalytic converter on your vehicle due to an inspection and maintenance (I/M) inspection failure or a non-I/M program-related reason, such as damage resulting from a vehicle accident, cracked or melted substrate, exhaust leak, or converter malfunction. Depending on your vehicle, the replacement could be an aftermarket catalytic converter (AMCC) or an OEM replacement part.

Part 218 (leaves DEC website) prohibits selling, offering for sale, advertising or installing used, recycled, or salvaged catalytic converters. Part 218 also requires a new California Air Resources Board (CARB) AMCC (leaves DEC website) or OEM replacement part be installed in a CARB or 50-state emissions certified vehicle of model year 1993, 1994, 1996 or newer. Additional guidance is available (PDF) for determining the appropriate CARB AMCC to use on vehicles for which a CARB-approved AMCC does not exist. New York State vehicle owners cannot take their vehicles to a neighboring state to have a non-compliant AMCC installed. This practice is not allowed by Part 218 and is subject to enforcement. Non-compliant AMCCs may be less expensive, but they are not required to provide the warranty coverage of AMCCs certified by CARB. Vehicle owners may also encounter problems in being able to pass the annual New York State motor vehicle emissions inspection (leaves DEC website).

Vehicle Emissions Certification

The vehicle emission control information (VECI) label, located in the vehicle's engine compartment, includes emissions certification, engine family or test group, engine displacement, on-board diagnostics, model year, fuel type, and catalyst information. Sample VECI labels are available for download (PDF). If the VECI cannot be located, an OEM dealer may be contacted to obtain a replacement VECI label containing the correct test group or engine family information.

Emission Warranties

Most vehicles purchased in New York State prior to 2016 are covered under the federal emissions warranty of 8 years or 80,000 miles. Partial zero emissions vehicles are covered under federal emissions warranty for up to 15 years or 150,000 miles. You can verify your vehicle's warranty by checking the owner's manual or by contacting an original equipment manufacturer (OEM) dealership and providing your vehicle identification number (VIN). Warranty coverage begins on the date the vehicle was first registered.

New CARB certified AMCCs, required for CARB and 50-state certified vehicles, will be covered by a warranty for a period of 5 years or 50,000 miles of use, whichever comes first. The warranty will cover defects and failures related to emissions performance and converter construction. The warranty covers loss of conversion efficiency, onboard diagnostic (OBD) system malfunctions, converter shell and pipe corrosion, and faulty welds that may occur during normal usage. The warranty does not provide coverage for defects due to overfueling, engine misfire, or physical damage caused by road debris or accidents.


The cost of new CARB AMCCs is higher, compared to a federal or non-compliant AMCC, primarily due to the increased catalyst loading required. This increased purchase price is partially offset by more robust warranty coverage.

Information for Businesses and Repair Shops

DEC has adopted California's AMCC requirements that include the prohibition of installing used catalytic converters and standards for new AMCCs. The requirements of subdivision 218-7.2(c) (leaves DEC website) apply to all:

  • model year 1993 and newer on-road motor vehicles, with the exception of 1995 model year vehicles,
  • vehicles certified by CARB or with 50-state emissions certification.

Subletting AMCC Repair and Installation

A repair shop can sublet AMCC replacement to another business, such as a muffler shop. The sublet business is required to establish and document the need for replacement even if the replacement was done by the original repair shop. If a repair shop sublets work out to another shop, the repair shop makes a fourth copy of the warranty card to keep in its records.

Non-Compliant AMCCs

It is illegal to install non-compliant AMCCs in New York State. Part 218 states "It is unlawful for any person to install, sell, offer for sale, or advertise … " which enables DEC to pursue enforcement against any person responsible for the sale or installation of a non-compliant AMCC.

The penalty structure for violations of the AMCC standards incorporated in Part 218 are set forth in New York State Environmental Conservation Law §71-2103 and §71-2105 (leaves DEC website). Violations are subject to minimum penalty of $500 for a first violation and up to $26,000 for each subsequent violation. This penalty structure is identical to the one which is used to enforce new vehicle sales under Part 218. A violation would be for each non-compliant converter sold and/or installed. Failure to maintain complete records or submit reports may also result in a violation. DEC periodically conducts audits at facilities to ensure compliance with the requirements of Part 218.


DEC's enforcement of the AMCC standards for the period January 1, 2019, to December 31, 2020, has resulted in:

  • 201 AMCC audits conducted
  • 124 violations of the AMCC standards discovered
  • 13 Notices of Violation issued
  • Fines ranging from $500 to $5,000
  • $13,500 in penalties collected

Since enforcement of the AMCC standards began January 1, 2014, there have been:

  • 1,028 AMCC audits conducted
  • 458 violations of the AMCC standards discovered
  • 150 Notices of Violation issued
  • Fines ranging from $500 to $5,000
  • $100,500 in penalties collected

Certification, Manufacturing and Distribution

For new AMCCs, the certification process typically takes 6-12 months to complete. CARB indicated that manufacturers can aid this process by ensuring that all required emission testing is completed and that all files submitted electronically to CARB are accurate and in the correct XML file format to be entered into CARB's searchable AMCC database (leaves DEC website). New AMCCs for CARB and 50-state certified vehicles will be required to:

  • Display a permanent etching, stamp or label on the catalytic converter shell showing the CARB Executive Order approval number, the manufacturer part number, date of manufacture, and proper installation direction.
  • Comply with a vehicle's original emissions certification limits.
  • Be compatible with the onboard diagnostic systems (OBD II) on 1996 and newer vehicles.
  • Be covered by a warranty for a period of 5 years or 50,000 miles of use, whichever comes first. The warranty will cover failures related to construction defects, performance defects, and OBD II compatibility issues.

Distribution centers located in the State may continue to supply EPA-certified AMCCs for only federally certified New York State vehicles or for sale outside of the State.

Manufacturer Reporting Requirements

Manufacturers of AMCCs are required to submit semi-annual warranty information and sales data to DEC. The reports are identical in format to those submitted to California and must contain:

  • the manufacturer's name
  • a description of each class or category of California-certified new AMCCs, including:
    • model year and series
    • the cumulative number and percentage of catalytic converters covered by the CARB Executive Order
    • the number of each type of catalytic converter produced for sale
  • New York State sales data

If confirmed warranty claims for new AMCCs in the State exceed 4% or 100 claims, whichever is greater, the manufacturer is required to submit additional information in the warranty information report. This required information includes:

  • type of failure,
  • probable cause of the failure, and
  • an evaluation of the impact on vehicle emissions.

The State is not requiring AMCC manufacturers to submit quarterly quality control reports at this time. Taxi cabs are not exempt from AMCC emission warranty reporting requirements.

Research Publications and Technical Papers

The Bureau of Mobile Sources and Technology Development, in the Division of Air Resources, carries out experimental research and technical and scientific analysis in support of emissions control program initiatives. Staff also collaborate with scientists from other institutions and co-author reports that may appear in other forums such as the Society of Automotive Engineers (SAE).

Advanced Clean Cars II (ACC II) Emissions Summary for New York State (Excel)

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