The Obama administration is abandoning its plan to immediately tighten air-quality rules nationwide to reduce emissions of smog-causing chemicals after an intense lobbying campaign by industry, which said the new rule would cost billions of dollars and hundreds of thousands of jobs, officials said Friday. The Environmental Protection Agency, following the recommendation of its scientific advisers, had proposed lowering the so-called ozone standard from that set by the Bush administration to a new stricter standard that would have thrown hundreds of American counties out of compliance with the Clean Air Act. It would have required a major effort by state...