The Bush administration says it will commit an additional $60 million in next year's federal budget to a program aimed at reducing unhealthy diesel exhausts from school buses.

U.S. Environmental Protection Administrator Mike Leavitt will be in Pittsburgh today to announce that the administration will seek the increased funding for the Clean School Bus USA program in 2005. The money will go for grants to replace pre-1991 school buses with new ones offering state-of-the-art emission controls and safety features, and to retrofit post-1990 school buses with similar advanced emission controls.

The school bus program is the third environmental initiative unveiled this week by Leavitt, who has traveled to Maryland and Michigan to announce Chesapeake Bay and Great Lakes cleanup projects. Environmental groups have criticized the blitz "as a public relations offensive in election battleground states'' after President Bush failed to mention the environment in his State of the Union address.

The EPA estimates that 220 school districts nationwide will benefit from the expanded bus replacement and retrofitting program. EPA's goal when it started the program last year was to upgrade the nation's entire school bus fleet of 444,000 vehicles by 2010.

Leavitt will make the announcement at the North Allegheny School District's McKnight Elementary School in McCandless. The district, which received $125,000 in October to install exhaust reduction devices on all 100 of its full-sized buses, is one of 17 districts across the country to participate in the program's pilot year projects.

Joy Ed, a spokeswoman for the district, said it is in the process of installing the muffler-like cleaning devices, known as diesel oxidation catalysts, on its bus fleet.

The catalysts use a chemical process to break down pollutants in the exhaust systems of buses and transform them into less harmful components. They can reduce soot by 20 percent, carbon monoxide by 40 percent and hydrocarbons by 50 percent.

Sue Seppi, executive director of the Group Against Smog and Pollution, which has waged a campaign to reduce school bus idling and exhaust emissions in Allegheny County, said the federal program begins to address a serious health problem.

"It's very important that we reduce these diesel emissions because the more we can do the healthier we will be,'' said Seppi, who was invited to join Leavitt at the elementary school.

Most of the nation's school buses are fueled by older, dirtier diesel engines, exposing the more than 24 million children who ride buses to school every weekday to soot, toxins and fine particles that can trigger or worsen asthma attacks.

The disease is the leading single cause of childhood hospitalizations, long-term illnesses and school absenteeism, accounting for more than 14 million missed school days nationally each year. Pennsylvania has the third-highest number of children with asthma in the country.

Seppi urged the administration to expand its emissions reduction program to other long-running, diesel-powered vehicles including garbage trucks, heavy duty trucks and public buses.

"I hope the government continues to provide funding until the job gets done,'' she said. "Diesel exhaust is an issue our group has focused on for the last year so I have to give credit where credit is due. Maybe this program will set an example for the administration to follow in areas where it has exhibited less advocacy and in some others where its performance has been dismal.''

Over the long run, federal regulations tightening the emissions standards of all diesel-powered vehicles and machinery in 2007 and the phase-in of ultra-low sulfur fuel between 2006 and 2010 will make bus exhaust 90 percent cleaner.