Reuters: Arizona challenged in federal court U.S. environmental regulators efforts to force Arizona power companies to spend up to $1 billion to install pollution control equipment at three coal plants to reduce haze in the region's national parks. Arizona's Attorney General Tom Horne said in a statement last week the emission control measures proposed by the U.S. Environmental Protection Agency (EPA) would not affect health or be reduce emissions visible to the human eye. "This is an absurd action that...