The CPI also ignores the direct cost of property taxes--sure to go up as states and cities bail out underfunded pension plans--and subtracts the "hedonic" effects of regulations that increase quality of life, such as the added expense of pollution-reducing gasoline additives.

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But when it comes to reducing pollution-causing emissions, electric vehicles have a lot of competition from cars powered by natural gas.

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Governments are solidly behind the new vehicles, which they see as essential for bringing down carbon-dioxide emissions and reducing pollution in cities.

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The environment has moved to the top of their political agenda, and they have promised increased environmental investment, set impressive targets for reducing pollution and launched grand-scale campaigns to address particularly challenging problems of environmental degradation.

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"With proper regulation and enforcement, gas provides a very substantial health benefit in reducing air pollution, " compared with coal-fired power plants, said Daniel Schrag, director of Harvard University's Center for the Environment.

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ATLANTA, Georgia (CNN) -- When there's talk of reducing air pollution, electric vehicles seem to get much of the attention.

CNN: Natural gas vehicles on a roll in U.S.

Nanotech also allows for "green manufacturing"--manufacturing processes that can take place at ordinary temperatures, reducing energy costs, while the use of non-toxic catalysts minimize pollution and bottom-up construction leaves no wasted material behind.

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But the traffic increase has slowed progress in reducing emissions further, and people in many areas still suffer from nitrogen-related air pollution, including small particulates that get sucked deep into the lungs, and ground-level ozone - a strongly irritant gas formed by the action of sunlight on reactive nitrogen.

BBC: Nitrogen pollution 'costs EU up to ?280bn a year'