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| Tier emissions standards | |
|---|---|
| Name | Tier emissions standards |
| Caption | Emission testing on a chassis dynamometer |
| Jurisdiction | United States |
| Enacted by | United States Environmental Protection Agency |
| Status | Active |
Tier emissions standards are a set of phased United States Environmental Protection Agency regulatory levels for pollutant emissions from internal combustion engine vehicles and engines, implemented to reduce harmful air pollution and improve public health. They establish progressively stringent limits, testing procedures, and certification processes affecting manufacturers such as General Motors, Ford Motor Company, Chrysler, Toyota Motor Corporation, Honda Motor Co., Ltd., BMW, and Daimler AG. The standards interact with other laws and programs including the Clean Air Act, California Air Resources Board, Corporate Average Fuel Economy, and international agreements.
Tier emissions standards set numeric limits for pollutants including nitrogen oxide, carbon monoxide, particulate matter, and hydrocarbons for categories such as light-duty vehicle, heavy-duty vehicle, off-highway vehicle, and marine vessel engines. They require manufacturers to demonstrate compliance through certification processes involving test protocols developed by the United States Environmental Protection Agency and coordinated with the California Air Resources Board. The standards are implemented in phases (e.g., Tier 1, Tier 2, Tier 3) that align with technological adoption by industry participants like Bosch (company), Continental AG, Delphi Automotive, and Cummins Inc..
Development traces to amendments to the Clean Air Act and research by agencies including the National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and National Institute for Occupational Safety and Health. Early federal actions followed litigation and rulemaking involving stakeholders such as Environmental Defense Fund, Natural Resources Defense Council, American Automobile Association, and automaker coalitions. Milestones include introduction of Tier designations aligned with scientific assessments from institutions like Harvard School of Public Health, Johns Hopkins Bloomberg School of Public Health, University of California, Berkeley, and Massachusetts Institute of Technology. International incidents and agreements, including discussions at United Nations Environment Programme forums and influence from standards in the European Union and Japan, shaped subsequent tiers.
Tiers apply across sectors regulated by the United States Environmental Protection Agency and state agencies such as the California Air Resources Board, affecting manufacturers, importers, and fleet operators including United Parcel Service, Federal Express Corporation, United States Postal Service, and municipal transit authorities like Metropolitan Transportation Authority (New York) and Los Angeles County Metropolitan Transportation Authority. They intersect with programs managed by agencies such as the Department of Transportation and National Highway Traffic Safety Administration when vehicle fuel-economy, safety, and emissions overlap. Exemptions, averaging, banking, and trading provisions involve registries and market participants like New York Stock Exchange listed suppliers and service providers.
Technical provisions specify dynamometer cycles, onboard diagnostics, evaporative emissions tests, and cold-start procedures developed in consultation with laboratories including Oak Ridge National Laboratory, Argonne National Laboratory, Sandia National Laboratories, and private testing firms. Test procedures reference specific duty cycles (e.g., FTP-75, US06) and measurement methods for oxides of nitrogen and particulate matter using instruments from firms such as Horiba (company), AVL List GmbH, and Toyo Seiki Co., Ltd.. Requirements prescribe use of technologies like three-way catalytic converter, selective catalytic reduction, diesel particulate filter, exhaust gas recirculation, and gasoline direct injection calibration, with guidance influenced by standards bodies including Society of Automotive Engineers and International Organization for Standardization.
Certification processes are administered by the United States Environmental Protection Agency and may be supplemented by state certifications from agencies such as the California Air Resources Board. Enforcement actions have involved civil penalties, recalls, and consent decrees with entities like Volkswagen AG, Fiat Chrysler Automobiles, and suppliers, often coordinated with the United States Department of Justice. Compliance mechanisms include in-use compliance testing, warranty provisions, reporting requirements, and fleet compliance programs used by corporate fleets from Amazon (company) and municipal agencies. Legal challenges have been heard in courts including the United States Court of Appeals for the District of Columbia Circuit and the United States Supreme Court.
Tier standards aim to reduce pollutants linked to respiratory and cardiovascular disease as documented by research from World Health Organization, Centers for Disease Control and Prevention, American Lung Association, and clinical studies at Mayo Clinic and Cleveland Clinic. Modeled benefits include reductions in ozone formation and fine particulate matter concentrations, with economic and public-health valuation by agencies such as the Office of Management and Budget and Council of Economic Advisers. Environmental outcomes intersect with climate policies overseen by Intergovernmental Panel on Climate Change assessments and national commitments under frameworks negotiated at United Nations Framework Convention on Climate Change conferences, including the Paris Agreement.
Tier standards influenced and were influenced by international regulatory regimes such as the European Union Emission Standards, Japan Ministry of the Environment standards, and protocols in countries like China and India. Comparative analyses involve automotive markets and manufacturers across regions including European Automobile Manufacturers Association, Japan Automobile Manufacturers Association, and China Association of Automobile Manufacturers. Technology transfer and harmonization efforts occur through forums like the United Nations Economic Commission for Europe and technical cooperation with agencies including International Energy Agency and non-governmental organizations such as Transport & Environment.