A new Ford engine said to boost fuel economy 20 percent and reduce CO2 emissions by 15 percent.

AP / Mark Duncan

A coalition of environmental groups and health organizations report they are optimistic that they can take substantial steps this year to reduce the dangerous pollutants emitted by heavy duty diesel engines.

A key step may be legislation that commits the state Department of Transportation to focusing on cleaning up the diesel emissions at three large construction sites that could have the largest impact on the public. One probably would be the demolition of the old Route 195 structures.

The three-project concept is a compromise from earlier legislation that called for more sweeping changes in the construction industry. That bill prompted opposition from some contractors and unions.

The compromise bill is scheduled to be heard by the Senate Environment and Agriculture Committee on Wednesday after the full Senate meeting adjourns. The Senate bill, sponsored by Sen. Josh Miller, D-Providence, and others, is S-0491.

Also important are plans to spend millions of dollars in federal stimulus money to clean up emissions from state vehicles powered with diesel engines, particularly buses operated by the Rhode Island Public Transit Authority.

RIPTA plans to spend some $37 million on hybrid buses, which will reduce fuel consumption and emissions.

The state Department of Environmental Management has about $3.5 million to retrofit school buses.

T.F. Green Airport is spending $182,000 to retrofit diesel vehicles at the airport.

And the state has assembled about $2.2 million, mostly from federal stimulus grants, to retrofit diesel vehicles operated by other state agencies.

Members of the Rhode Island Diesel Pollution Initiative and Clean Water Action hosted a status report Thursday in the State Room at the State House.

They displayed a video showing a measuring device placed up against the exhaust pipe of a diesel engine equipped with a filter. It scarcely registered any emissions. Placed against an unfiltered engine, the meter shot straight up.

Only in the last few years have federal regulators appreciated the toxicity of the ultra-fine particles emitted by diesel engines, according to Annie Costner of Clean Water Action. The particles are so fine they are transferred from peoples’ lungs into their blood and then to their heart and other organs, where they cause damage.

“Never before has this issue gone as far as it has this year,” Miller said of the legislation. He said as efforts were made to amend the legislation, he saw contractors and union leaders express support.

“All are getting on the same page with awareness that this is a problem,” Miller said. “This bill brings federal, state and contractor resources to the task.”

Dr. Nicholas Tsiongas, an occupational health specialist, said the Rhode Island Medical Society is pleased to be part of the diesel coalition.

“There are people who are made more ill and people who have died because of diesel pollution in the air,” Tsiongas said.

Costner says it costs about $10,000 to retrofit a typical diesel vehicle but it can cost much more for bigger machines. New diesel engines use cleaner technologies.

Matthew Stark, the Providence police and legislative affairs director, said the city has a major program to upgrade its diesel equipment.

plord@projo.com