(FORTUNE Magazine) – If you thought the regulatory demands of the Clean Air Act would affect people only in the belching smokestack trades, please think again. Office workers who don't even have as much as bad breath are going to be affected by new commuting requirements in ten of the country's biggest metropolitan areas, including New York, Los Angeles, Philadelphia, Houston, and Milwaukee. The act, which was passed back in 1990, requires companies that have more than 100 employees in these cities to reduce the number who drive solo to work. Specifically, employers are expected to achieve an "average vehicle occupancy" rate that is 25% higher than the regional rate. Some companies are already out of the gate. On a corporate strip in suburban Chicago, for instance, several major employers have banded together to promote ride sharing. "Car and van pools require a critical mass," says Bruce Osborne, VP of administration at Dean Witter Discover's card headquarters. So Osborne set up a database with his neighbors, which include Baxter International and Walgreen.

| Each company has a kiosk in the lobby where employees can log in their address and work hours; out pops a list of people with whom they can share the ride. The companies line up vans and share the cost. If you plug in how many miles your car gets per gallon, the kiosk will tell you how much money you'll save by pooling. The participating companies also offer a "guaranteed ride home," which means that employees who take part in a pool are promised a free taxi ride if they have to work late or leave early for an emergency. Since the program began last September, says Osborne, his company alone has taken 170 cars off the road.