And the Golden State hasn’t, well, let off the gas. “Every step of the way, California adopted a more aggressive required standard,” says Dan Sperling, the founding director of the Institute of Transportation Studies at the University of California Davis, who sits on the California Air Resources Board.
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California cranked up its efforts in 1975, setting newly strict emission standards for light-duty cars. Automakers who wanted to comply—and sell cars in the country’s biggest market—started equipping virtually all their vehicles with catalytic converters, which remove smog-forming hydrocarbons from exhaust gas. That in turn required the phaseout of leaded gasoline, as lead reduced the devices’ effectiveness. The EPA required gas stations to start offering unleaded fuel and made automakers use narrower tank inlets, so only the slender nozzles pumping the clean(ish) stuff could be used. By 1992, leaded gasoline, which contributes to all sorts of health problems, was no longer available in the US.
In 1977, an amendment to the Clean Air Act allowed other states to adopt California’s rules. None did so right away, but today, 13 do so; together with California, they represent one-third of US car sales. Those pioneering rules, Sperling says, also became models for countries in Europe and Asia, including Japan and China, looking to get a handle on car-caused pollution.In 1990, the state tightened its standards again, and added a new component: Its Low-Emission Vehicle program required that automakers sell some zero-emission vehicles, as in battery and fuel-cell electric cars. That program pushed General Motors to develop the EV1, which soon ended up in a junkyard but prepared the automaker to roll out the hybrid Chevy Volt in 2011 and fully electric Chevy Bolt in 2016. The program also rewarded hybrids, which now sell by the millions.
In 1999, during a stretch where the EPA let national standards stagnate, California added a rule addressing pollution caused by fuel evaporating from gas tanks in hot weather, pushing automakers to redesign their fuel tanks. And in 1998, it expanded its rules to include the hulking minivans and SUVs Americans had come to love, and strengthened the rule governing nitrogen oxide emissions, which would ultimately land Volkswagen in a heap of trouble .