Nearly 190 employers offer enough commuting options to their workers to significantly help the Washington area's traffic and air quality, according to the Environmental Protection Agency, which will release lists today of the best local and national workplaces for commuters.

The company programs, covering a combined 179,000 workers, encourage employees to telecommute, bike, walk, carpool and do other things to cut the number of single-occupancy vehicles on the roadways.

EPA officials estimated that there are 3.8 million commuters in the Washington region, and about 70 percent of them travel alone in their vehicles.

Nikki Diamantes Bateman, a senior program analyst at Alexandria-based Calibre, said she is more than happy to leave her car in the driveway and take advantage of her company's telecommuting program.

"For me, it's fabulous to have the flexibility," she said. "Instead of sitting in traffic, I spend the whole day focusing on what I need to do." She said it makes Calibre more appealing and makes her less likely to leave.

EPA officials said the best workplaces program -- the national survey started in 2001 and the local one began last year -- has fast become one of the agency's most successful efforts to get cars off the road because it helps businesses understand that there is money to be made in reducing commuter grief.

"Some are able to get enough of their employees to switch to forms of transit that they don't need to spend $10 million on a parking garage," said Jeff Holmstead, assistant administrator for air and radiation at the EPA. Others, he said, find that telecommuting programs allow them to reduce office space.

Holmstead said results show that 15 to 30 percent of employees sign up for commuter programs after companies start them.

"Our calculation is that if half of all employees in the country had access to these benefits, the reduction in traffic and air pollution would be the equivalent of eliminating about 10 million cars from the road," Holmstead said. As it stands, 2 million of about 140 million workers nationwide have such access, agency officials said.

To qualify as a best workplace, companies must pay commuters to take transit or offer an extensive telecommuting program; they must offer at least three other benefits, such as showers for bicyclists, on-site day care or incentives to live near work; they must have a commuter program director; and they must provide access to a program that guarantees a ride home in an emergency for workers who use public transportation.

Making it onto the EPA list garners employers little more than the agency's stamp of approval and some public recognition, but executives said they have found that it also helps their recruiting and retention efforts and bolsters productivity.

"It's a pretty good incentive," said Ron Kirby, transportation planning director for the Metropolitan Washington Council of Governments. "People really want to be on the list."

Bethesda-based Discovery Communications offers the usual slate of options -- telecommuting programs and flexible work schedules -- but the firm also offers bicyclists a one-time check for $350 if they pedal in a certain number of days, a $100 yearly benefit for shoes for walkers and a locker room for both.

"Certainly the environmental impact is important and the transportation issue is part of it, but it's good business sense for us," said spokesman David Leavy.

"It's really driven for retention, recruitment and to push the workforce to be productive and creative."

The number of local companies that meet the federal guidelines more than doubled from last year, when 76 employers qualified. Leading the charge locally was Fannie Mae, which also ranked second on the national list of the best workplaces for Fortune 500 firms. Among other things, the mortgage finance company provides free shuttle service for employees traveling between local offices, up to a $100-a-month transit subsidy and an extensive telecommuting program.