America is currently searching for the best way to move from traditional fossil fuels to alternative fuels, but in the 1970s, a smaller-scale nationwide fuel change was accomplished -- the switch from leaded to unleaded fuel.

The reasons behind the quest for alternative fuels include economic and environmental issues, while the push for unleaded fuel was mainly due to health concerns. The process took decades.

Gasoline does not naturally include lead. But in 1923, automakers discovered that adding tetraethyl lead to petroleum dramatically reduced engine "knocking" -- when the fuel starts to combust too early and can damage the engine -- and increased engine efficiency. Leaded fuel was soon manufactured and sold across America and eventually, the rest of the world.

But health concerns emerged from the beginning.

"Since the 1920s, the health community had raised concerns about lead in gasoline," said Environmental Protection Agency deputy press secretary Jessica Emond. "The body of evidence grew over the years that young children were particularly at risk for lead poisoning from leaded paint and leaded gasoline."

Children could be exposed to lead directly from inhaling exhaust emissions and indirectly from soil and water where that lead accumulated. The exposure was found to increase the risk of developmental disorders, anemia and other problems in children.

In addition to health concerns, lead emissions also caused environmental damage.

"Lead is persistent in the environment and accumulates in soils and sediments through deposition from air sources, direct discharge or waste streams to water bodies, mining and erosion," said Emond in an e-mail interview. "There are known effects on plants and animals at locations subject to the extremely high concentrations of lead."

So when the Clean Air Act was passed in 1970, it listed lead as a chemical toxin and called for a gradual phase-out plan for lead in gasoline. The first lead phase-out standards were set in 1973.

Challenges to industry
In order to meet Clean Air Act mandates, the auto industry developed new tailpipe standards that required cars to use a catalytic converter.

"The catalytic converter -- a piece of hardware that's put on a tailpipe -- reduces the emissions coming out of the tailpipe," said Al Mannato, fuels issues manager at the American Petroleum Institute. "The reason lead had to come out of gasoline initially was because it would poison the catalytic converter."

The new catalytic converters forced fuel developers to come up with ways of maintaining efficiency without lead. Although automakers were able to design new cars that didn't use leaded fuel, older vehicles were still allowed to run on leaded gasoline, and the petroleum industry had to provide both options for their consumers. Because of these factors, the American auto industry took a financial hit during the switch from leaded to unleaded gasoline.

"The fiscal impact was pretty devastating," said Loren Beard, senior manager of environmental and energy planning at the DaimlerChrysler Corp. "The onslaught of the Japanese carmakers coming in with a good product and lower manufacturing costs really hurt the industry. The U.S. auto industry never really recovered."

In addition to being fiscally damaging to the auto industry, making the switch to unleaded fuels came with other challenges. One challenge was meeting the high octane ratings that had become standard in cars. Octane helps to reduce engine damage from knocking.

"At first there was a shortage of octane, because lead provided a lot of octane to fuels," said Beard. "There was a lot of downsizing of engines and lowering of horsepower."

In order to encourage the phase-out of lead, the government gave oil companies financial incentives to develop unleaded fuels that still contained high levels of octane, maintaining their efficiency. Tax incentives were also available to refineries to stop producing leaded fuel, said Mannato.

U.S. goals achieved, international challenges remain
Despite the challenges, the goals set by the EPA were achieved. By 1995, only 0.6 percent of the gasoline sold in the United States contained lead, and in 1996, the sale of leaded gasoline in the United States ended. From the mid-1970s to the mid-1980s, the levels of lead in the human blood stream dropped by 50 percent in the United States, according to EPA reports.

"The nation's air is cleaner than it's been in a generation," said Emond.

The United States is now working with the World Bank's Clean Air Initiative and the United Nations to help phase out lead around the world. Although the United States and Europe were able to phase out lead fairly quickly, many developing countries still depend on leaded fuel.

"In much of the developing world lead additives are still widely used, especially in Africa," the World Bank Group reported in 2000. "Experts suspect that in developing countries all children under 2 and more than 80 percent of those between 3 and 5 have blood lead levels exceeding World Health Organization standards."

New regulations
Now, automakers are worried Congress and the EPA will set emissions standards that would require them to redesign cars on too tight a timetable, but some analysts say progress can be made without changing engines at all. Switching to fuel that is 10 percent ethanol would not require much change, said Doug Arent, director of the Strategic Energy Analysis and Applications Center and a senior visiting fellow at the Center for Strategic and International Studies.

"All cars are compatible with relatively low blends of ethanol," Arent said.

Traditionally, the auto industry has had a somewhat "adversarial relationship" with the EPA, said Beard. "There's always a back and forth. ... Our main concern is that we not have legislation that is too aggressive. Provided that we get cooperation with the EPA and the oil industry, National Highway Traffic Safety Administration and everyone works together, we don't have any reason to believe that things won't go smoothly."

Arent, meanwhile, said some regulation will still be necessary. "Everyone has their own perspective and vested interest, where they're looking out for their corporation and their investors," he said. "I expect there to be a continued heated debate. I think the EPA is being very careful to build stakeholders into the rule-making process, but they still have a mandate to propose reasonable regulation."

-- By Alexis Matsui, Online NewsHour