The US Environmental Protection Agency (EPA) has launched a massive programme to test diesel emissions to ensure they comply with new standards.

New and more accurate technology will be used to ensure that diesel truck and bus emissions are not going above the new limits stipulated by the government.

The initiative will see portable measuring devices attached to engines while the vehicle is in motion to assess exhaust emissions of hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter.

The new method will be much more efficient, since previous testing of emissions required the engine to be removed from the truck and be tested in laboratories.

"This programme is a dramatic addition to the EPA's clean diesel campaign and will result in healthier air for all Americans," said EPA assistant administrator for air and radiation, Jeff Holmstead.

"This collaborative effort with engine manufacturers will help ensure that diesel trucks run cleaner for as long as they are on our roads."

A pilot programme is due to begin this month and the EPA has asked manufacturers to recruit volunteer test vehicles from fleets or individual owners.

It is expected to expand nationwide starting with 2007 model year diesel trucks.

The programme is the result of cooperation between the EPA, the California Air Resource Board (ARB), and diesel manufacturers within the US.