At sites from Ground Zero to a Chicago expressway to a California airport, the notoriously dirty construction industry is starting to clean up its act. P> Instead of belching black smoke, the bucket loaders, cranes and other diesel-powered behemoths at these construction projects are part of a new generation of relatively clean heavy equipment meant to mitigate the environmental effects of often-controversial building projects.

By using pollution-scrubbing exhaust filters and cleaner-burning fuel, officials in charge of getting such massive projects approved are finding it easier to win community support. In some places, local leaders are insisting on their use as a condition of backing noisy projects that can disrupt traffic, kick up dirt and foul the air.

"There is a strong voice from the community for better air quality," says Thomas Kunkel, environmental director for the Lower Manhattan Construction Command Center, a state agency overseeing building in the neighborhood around the World Trade Center.

In response to demands from neighboring communities, Los Angeles International Airport officials agreed to use the cleaner construction vehicles in an $11 billion expansion that began in July. In Chicago, the cleaner vehicles are being used to widen Chicago's Dan Ryan Expressway and are planned for the enlargement of O'Hare International Airport. They are also involved in Connecticut's rehabilitation of Interstate 95. Boston's "Big Dig," a decade-long highway relocation completed this year, was an early pilot project.

Federal air-quality requirements are helping motivate the switch to cleaner-running equipment. Construction vehicles are among the largest sources of air pollution. There are around two million "off-road" construction vehicles in the U.S., compared to around 200 million cars and trucks. Yet a typical 175-horsepower bulldozer emits as much particulate matter as 500 cars, according to the Environmental Protection Agency.

The burning of diesel fuel kills 12,000 people prematurely each year and causes one million missed workdays and 6,000 emergency-room visits for children with asthma, the EPA says. It's not the black smoke from the diesel exhaust that causes the most health problems, but rather tiny particulates, 1/60th the width of a human hair, that lodge in the lungs and cause respiratory distress. A combination of using ultra-low sulfur fuel and exhaust filters can reduce particulates up to 90 percent.

Scrubbers on construction equipment work by trapping the fine particulates in filters made of metals such as platinum. The particulates are then baked at a high temperature, rendering them less harmful.

The EPA -- which didn't regulate construction emissions until the mid-1990s, and then only lightly -- is planning to phase in stronger regulations for new vehicles between 2008 and 2014. Environmental groups are pushing for more. Existing equipment wasn't affected by the EPA regulations; noting the average bulldozer or backhoe remains in operation for two to three decades, Diane Bailey, a diesel expert at the National Resources Defense Council says "the full benefits of those standards won't be achieved until beyond 2030." Her New York-based group and others are promoting the retrofitting of existing vehicles with scrubbers or new engines.

In New York last week, Gov. George E. Pataki signed legislation ordering many existing state vehicles, including construction equipment, to use cleaner fuel and install particulate filters.

Contractors are wary of regulations that would require them to move faster. The American Road & Transportation Builders Association filed a pending petition in federal appeals court in Washington in March to preempt any state from imposing blanket regulations that would regulate construction equipment. Associated General Contractors also reject the idea of contract requirements or bidding preferences that favor the use of clean-burning equipment. "It's extremely expensive to retrofit," says Leah Pilconis, environmental counsel for AGC. A new engine can cost upward of $25,000 for a large construction vehicle. A retrofit filter costs around $10,000 to $15,000. She says her industry favors voluntary, incentive-based programs like ones funded by the EPA, Texas and California, which encourage equipment owners to retrofit on their own.

Meanwhile, companies such as Donaldson Co., Caterpillar Inc., Deere & Co. and Corning Inc. are gearing up to meet demand for construction equipment and similar retrofits for school buses, garbage trucks and tractor trailers.

The move toward clean diesel vehicles is part of a broader move by governments and developers to use "green" building techniques. Contractors now recycle excess dirt, insulation and other materials generated on the work site. Some sites use special acoustical blankets and noise-reducing saw blades to drop the volume as buildings rise.

In Los Angeles, residents around the airport have complained for decades about poor air quality from the hundreds of jets and ground vehicles that prowl the airport. "There's going to be a huge project and we wanted to make sure the folks who live immediately adjacent are not heavily burdened by it," says Jerilyn Mendoza, policy director in the Los Angeles office of Environmental Defense, a New York-based nonprofit. She negotiated a "community benefits agreement" with the city that won promises to use of clean construction equipment. "We were trying to find specific things the airport was responsible for," she says, "and they were willing to think as creatively as possible to reduce the (pollution) sources."

At Ground Zero, health problems related to the Sept. 11 attacks are one impetus for clean construction. "It's clear that people's health has already been compromised" by the dust and smoke, says Julie Menin, chairwoman of Community Board 1, a governmental advisory group. "We're not going to allow this community to suffer additional effects."

Her group asked developer Larry Silverstein, who is building three of the five office towers there, to require his share of the 5,500 to 10,500 delivery trucks per month to use ultra-low sulfur diesel fuel. Mr. Silverstein, a life-long asthma sufferer, agreed. "We were delighted," Ms. Menin says.

In addition, local city and state rules require on-site equipment in the area to use the special fuel and to install the filters. The two tower cranes that will hoist the beams for the Freedom Tower will have modern engines that meet the future EPA requirements. "These are big engines and will be running constantly so the reduction in pollutants is significant," says Richard Kielar, vice president for Tishman Construction Corp., the construction manager on the project. He says the cost of using ultra low-sulfur fuel is negligible, since it's just a few cents more than regular diesel.

The Lower Manhattan Construction Command Center has three full-time inspectors who rove the area verifying that contractors are using the proper equipment and fuel. They also make sure trucks and equipment are turned off when not in use. Fines are around $1,500.

Tuesday, standing beside a massive drill rig that bores 80-foot deep pilings for a Metropolitan Transportation Authority subway entrance a block from the trade center, workers were happy with the new filters. "We're around the machine eight hours a day. We're breathing the air," says Mike Gallagher, a foreman on the project.

With the old machines, "there's black smoke everywhere," adds John Nieves, a mechanic with International Union of Operating Engineers Local 14 and under contract with Skanska Inc., a large contractor. "People don't like seeing construction in the street, so anything you can do to clean it up helps."