"The Diesel Emissions Reduction act of 2005 will provide pivotal funding through national- and state-level grant and loan programs for the voluntary retrofitting of existing diesel engines," said senator George Voinovich, Republican senior senator for Ohio, on introducing the bill.
"I am pleased that such a strong, diverse coalition of environmental, industry and public officials understands the need for this legislation and is working hard to make it a reality."
The US Environmental Protection Agency's (EPA) new fuel and engine regulations are predicted to cut emissions from new diesel engines by up to 80%. But the estimated 11 million existing heavy duty diesel engines, which are responsible for around 50% of particulate matter and nitrogen oxide emissions in the US, will continue producing emissions for the rest of their time on the roads.
"EPA's new diesel regulations will go a long way to cleaning the air, but it could take up to 25 years before today's current dirtier engines are replaced," said Tom Carper, Democrat senator for Delaware.
"This bill will help us meet our clean-air goals quicker, meaning less children being hospitalised for asthma and more lives saved."
The introduction of the act has attracted widespread praise from environmental and industry groups, including advocacy group Environmental Defense, a usually reliable critic of Republican environmental policy, and has received bipartisan senate support.