Taking into account everything from city design to engine technology, the California Air Resources Board has set a goal for reducing the state's airborne pollution to 10% below current levels by 2020. The broad sweep of the plan makes it the most comprehensive of any state in the U.S.

A cap-and-trade program on CO2 emissions will force buildings and the appliances within them to be more energy-efficient, drive oil companies to make cleaner fuels and require power companies to derive up to a third of their energy from renewable energy sources, such as the massive windmill farms and solar energy generation centers found throughout the state, reports Automotive News.

Making cities more amenable to pedestrians and shortening commutes is also a primary goal. Adding high-speed rail lines to take away from air travel and requiring more alternative-fueled vehicles will also help cut emissions and reduce pollutant levels.

The cost to business and industry is expected to be huge, however. The plan will become law in 2012 if approved, with measures gradually restricting more and more emissions sources through 2020. Government officials think that although there will some initial cost, the overall result will be of benefit to the state's economy, thanks to greater energy efficiency in the long run.