Times (UK): Building a third runway at Heathrow would make it ‘impossible’ to meet legally binding targets on air pollution, according to Lord Smith, head of the Environment Agency. In a speech tomorrow the government’s own green watchdog will increase pressure on ministers not to approve the expansion. Smith will tell his agency’s annual conference: ‘The government has committed itself to rigorous targets to emissions 80% by 2050, which now includereduce CO2 aviation and shipping. It is …