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International Programs

Transportation and Air Quality

Note: EPA no longer updates this information, but it may be useful as a reference or resource.


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Motor vehicles are a large source of urban air pollution in most urban areas. The main page of EPA's Office of Transportation and Air Quality outlines a variety of information resources, tools, and technologies to reduce air pollution from vehicles in the U.S. The information developed by EPA may be useful as other countries beginng to address mobile source pollution.

Internationally, EPA is a leading partner in the United Nations Environment Programme Partnership for Clean Fuels and Vehicles Exit EPA disclaimer, which was launched at the World Summit on Sustainable Development in 2002. the Partnership goals are to:

  • eliminate lead in gasoline world-wide; and
  • reduce sulfur in diesel and gasoline, while introducing cleaner vehicle technologies.

Additional information on motor vehicle emissions and air quality in the U.S.:

Fuels and Vehicles: The Systems Approach:
For the past 30 years, air pollution control programs have shown that cleaner fuels and vehicles are an effective pathway to cleaner air. In programs domestically and internationally, EPA treats fuels and vehicles as a system, with the greatest benefit achieved by combining cleaner fuels with appropriate vehicle and emission control technologies.


Sulfur in Fuels:

An important approach to reducing vehicle emissions is to lower sulfur levels in fuels. Lowering sulfur levels will result in immediate reductions of emissions from current vehicles and is a necessary step in enabling the use of improved catalysts, filters, and other technologies that can remove most of the pollution from today’s gasoline and diesel vehicles.

The following resources from the United Nations Environmental Programme (UNEP) and the International Council on Clean Transportation (ICCT) provide more information on sulfur in fuels:

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Diesel Fuels

EPA’s National Clean Diesel Campaign

Over the last five years, EPA has begun implementing a variety of programs designed to reduce emissions from the diesel fleet in the U.S. These programs focus on different sectors that provide the best opportunity for significant emissions reductions. These include school buses, ports, construction, freight, and agriculture. Further information can be found at the following websites:

Other resources for diesel emissions reductions include:

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Emissions from Diesel Fuels:

EPA Information:

Other Documents:

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International Diesel Retrofit Projects:

Mexico City Diesel Retrofit Project Beijing, China Diesel Retrofit Project Pune, India Diesel Retrofit Project Bangkok, Thailand Diesel Retrofit Project San Diego-Tijuana Diesel Retrofit Project

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Biofuels and Other Alternative Fuels

Phase-out of Lead in Gasoline

While the U.S. and many other countries have completed the phase-out of lead in gasoline, there are several areas of the world that still use leaded gasoline. People, animals, and fish are mainly exposed to lead by breathing and ingesting it in food, water, soil, or dust. Lead accumulates in the blood, bones, muscles, and fat. Infants and young children are especially sensitive to even low levels of lead.

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Vehicles and Engines

Cars and Light Trucks

Motorcycles, 2-stroke vehicles, and 3-Wheelers

Hydraulic Hybrid Vehicles

Importing Vehicles and Engines

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Emissions Modeling and Inventories

EPA was key in developing the International Vehicle Emission Inventory Model Exit EPA disclaimer, designed to better estimate emissions from mobile sources internationally. The model will help cities and regions to develop emissions inventories to:

  • Focus control strategies and transportation planning on those that are most effective;
  • Predict how different strategies will affect local emissions; and
  • Measure progress in reducing emissions over time.

In the United States, EPA uses a variety of models vehicle emissions inventories:

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Transportation Planning; Partnerships

Transportation planning is an important tool to use to cut emissions of both conventional pollutants and greenhouse gases. EPA resources include:

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