Allegheny County's recent decision to ban smoking in workplaces -- coming on the heels of a similar ban in Philadelphia -- represents one of the biggest cultural changes of our times. Such a ban would have been unthinkable 50 years ago, when cigarette commercials dominated the airwaves and glamorous movie stars lit up regularly on the silver screen.

Thomas Hylton is the author of "Save Our Land, Save Our Towns" and host of the public television documentary "Saving Pennsylvania" (thomashylton@comcast.net).

In recent years, 17 states and more than 500 local municipalities have enacted smoking bans. Cigarette sales have dropped 20 percent since 1998, when tobacco companies agreed to pay $248 billion to the states to help cover the costs of treating tobacco-related diseases. Today, about 20 percent of Americans smoke, half the percentage of 40 years ago.

This not only represents an enormous victory toward eradicating America's most deadly habit, it demonstrates that concerted public and private efforts can change negative social behavior, no matter how deeply ingrained. That's heartening for a number of reform movements, including attempts to protect Pennsylvania's farms and forests from another bad habit -- the low-density, drive-everywhere-for-everything lifestyle that has emasculated our cities and decimated our countryside in the last half-century.

Just as the surgeon general reported in 1964 that smoking was the leading threat to individual health, the 21st Century Environment Commission appointed by Gov. Tom Ridge in 1997 concluded that sprawling development is the No. 1 threat to Pennsylvania's environmental health. Sprawl, the Environment Commission said, consumes enormous quantities of farmland, isolates the poor in our cities and towns, creates massive traffic congestion, worsens air and water pollution, and requires exorbitant amounts of tax dollars to build and maintain.

But efforts to curb sprawl have gone nowhere, mostly for the same reason that efforts to curb smoking floundered in the first two decades after the surgeon general's report. Despite all the evidence of societal harm, smoking was considered an individual lifestyle decision that people had a right to make in a free country. Health workers concentrated on prodding smokers to "kick the habit" rather than emphasize the enormous economic costs and substantial health risks that smokers were inflicting on everyone else.

It was only when anti-smoking advocates changed tactics -- lobbying for smoking bans and higher taxes on cigarettes, suing tobacco companies to pay for the health care costs of smoking and campaigning about the dangers of second-hand smoke -- that tobacco use plunged. Cigarettes began to lose their allure only when smokers were forced to stand outside their office buildings to take a drag during work breaks.

Just as it once seemed almost impossible to attack smoking when more than half of the men in America were doing it, fighting sprawl is a daunting mission when the American dream still revolves around two-acre housing lots and three-car garages. But (to paraphrase Anatole France), if 50 million people do a foolish thing, it is still a foolish thing.

When John and Mary buy a new home that can be reached only by car, they are contributing to America's dependence on foreign oil and increasing the country's greenhouse gas emissions. They are helping squander Pennsylvania's open space, and they are raising the cost of government by compelling an inefficient network of roads and utility lines. Unfortunately, no one has brought home to John and Mary the negative effects of their decision -- both to them individually and to society. Meanwhile, government has been subsidizing such behavior, not penalizing it.

The Pennsylvania Department of Transportation is a good place to start changing the land-use paradigm. On Monday, a transportation commission created by Gov. Ed Rendell reported that an additional $1.7 billion is needed annually to maintain and improve the state's highways and mass transit systems -- about 40 percent more than Pennsylvania currently spends. The commission recommended raising the extra funding through a combination of higher state fuel and realty-transfer taxes, driver fees and local taxes.

While improving mass transit fights sprawl, building new highways does the opposite. Instead, PennDOT should expand its Home Towns Streets program that focuses on sidewalks and trails to encourage walking and bicycling as a means of transportation. Additional revenue should be raised by hiking gas taxes to discourage excess driving in the same way that higher cigarette taxes have discouraged smoking.

The Commonwealth Financing Authority should cut funding for projects on undeveloped land and restrict future loans and grants to projects on recycled land in existing cities, towns and older suburbs.

The state Department of Education should eliminate state funding for sprawling new schools on the urban fringe and require school districts to pay the entire $1 billion annual cost of busing students instead of covering half the bill.

And just as former Surgeon General C. Everett Koop prominently campaigned for a smoke-free society, Gov. Rendell should use his bully pulpit to promote sustainable communities -- ones that conserve resources, not waste them.

Pennsylvanians can be persuaded to adopt healthier lifestyles -- but it will take a concerted effort to get their attention and make it fashionable as well as practical to walk instead of drive.