...The U.S. Environmental Protection Agency will impose a stricter nationwide limit on ozone, or smog, next month, requiring further pollution cuts from vehicles and industries just as Houston complies for the first time with the current standard, set in 1997. Thanks to cleanup efforts, favorable weather conditions and a slumping economy that reduced emissions-producing business and transportation, Houston will achieve the standard of 84 parts per billion, or 84 molecules of ozone for every billion molecules of air, by the thinnest of margins this year. But the new limit, lowered on the basis of more recent medical evidence, will be...
