21.   Industry groups are asking the justices to rule that the Environmental Protection Agency must weigh the cost of reducing harmful emissions against the benefits of improved air quality.

22.   It called on industrialized nations to take action to fight global warming, including helping poorer countries develop techniques for reducing harmful emissions.

23.   It said the law does not require the government to consider the financial cost of reducing harmful emissions when it sets air-quality standards.

24.   Much of the industry excitement is for fuel cells, a technology that makes energy from a chemical reaction without harmful emissions.

25.   Much of the industry excitement is for fuel cells, a technology developed to power space vehicles that makes energy from a chemical reaction with no harmful emissions.

26.   The alternative form of fuel produces significantly less harmful emissions than petrol and diesel fumes.

27.   The court said the law does not require the government to consider the financial cost of reducing harmful emissions when it sets air-quality standards.