Greenhouse gases harm humans: Environmental protection agency

The Obama administration has taken a major step toward imposing the first federal limits on climate-changing pollution from cars, power plants and factories, declaring there was compelling scientific evidence that global warming from manmade greenhouse gases endangers Americans' health.

The announcement by the Environmental Protection Agency (EPA) was clearly timed to build momentum toward an agreement at the international conference on climate change that opened on Monday in Copenhagen, Denmark.

It signalled the administration was prepared to push ahead for significant controls in the United States if Congress doesn't act first on its own.

The price could be steep for both industry and consumers. The EPA finding clears the way for rules that eventually could force the sale of more fuel-efficient vehicles and require plants to install costly new equipment - at a cost of billions or even many tens of billions of dollars - or shift to other forms of energy.

No analysis has been conducted by the EPA on costs of such broad regulations, although the agency put the price tag of its proposed climate-related car rules at $60 billion, with an estimated benefit of $250 billion.

Energy prices for many Americans probably would rise, too - though Monday's finding will have no immediate impact since regulations have yet to be written. Supporters of separate legislation in Congress argue they could craft measures that would mitigate some of those costs.