Environmentalists called yesterday for the federal government to stop work on a disputed six-lane toll road across Montgomery and Prince George's counties, contending that there is new evidence that children and other residents living along the route could be harmed by pollutants from the traffic.
Two groups, Environmental Defense and the Sierra Club, said a study commissioned by one of them shows that construction of the 18-mile Inter-County Connector would violate tightened federal air-quality health standards on soot -- the fine particles emitted in vehicle exhaust and other forms of combustion.
The groups petitioned the U.S. Department of Transportation to withhold further approvals of the $2.4 billion project and re-evaluate the government's earlier finding that the highway would not seriously harm the environment or human health.
"We're asking that work on the project be halted until this supplemental environmental impact statement is made and provisions made for reducing the environmental impact," said Bob Yuhnke, a lawyer for Environmental Defense.
Pointing to studies showing that current air-quality standards were not protective enough, the Environmental Protection Agency cut nearly in half its safety threshold last fall for the maximum allowable level of soot in the air people breathe around the clock.
At the behest of Environmental Defense, E.H. Pechan & Associates Inc. projected that soot concentrations in the air along the ICC's route could increase anywhere from 14 percent to 100 percent or more, once the project is complete in 2012. The projection would put soot levels above EPA's new safety threshold on "many more" days of the year.
The smaller estimated increases in soot came from what the consultants called "seriously flawed" traffic projections used by federal and state officials in finding no harm from the project.
New scientific studies published since the highway project won federal approval last year have indicated that toxic pollutants from vehicle exhaust can aggravate asthma, harm children's lung development and contribute to heart disease and early deaths, said Dr. John Balbus, Environmental Defense's health program director.
Soot and other vehicle emissions could harm children who live, go to school or play within 500 meters of the ICC, the groups contend. The new highway is expected to handle more than 45,000 vehicle trips daily.
"Given this new information and the results of the study we're releasing today, we believe the Department of Transportation needs to go back to the drawing board and reevaluate its approval of the ICC," said Steve Caflisch of the Maryland chapter of the Sierra Club.
The petition comes six months after these groups and others opposed to the ICC filed a pair of lawsuits, contending that the federal government failed to thoroughly review the potential harm the highway could cause to the environment and to people living along the route.
Opponents have called for expanding public transportation instead, for improving the existing road network and for banning trucks from the ICC if it is built.
The long-debated project -- derailed by environmental concerns in the late 1990s -- was revived by Gov. Robert L. Ehrlich Jr. His Democratic successor, though otherwise in tune with environmentalists, has supported completing the project.
With Gov. Martin O'Malley's administration arguing that the ICC is needed to relieve Washington-area traffic congestion, Maryland successfully petitioned the federal court to be included in the cases.
A call to the Federal Highway Administration for comment on the petition was not returned.
Dave Buck, a spokesman for the State Highway Administration, said state officials have not seen the petition. He said officials are confident that the environmental impact study would hold up in court.
The SHA recently authorized design work on a seven-mile leg to intersect with Interstate 270 in Montgomery County. Construction of that portion, estimated to cost $478 million, could begin as early as this fall, Buck said.