 Following the publication of the White Paper , the Project for the Sustainable Development of Heathrow ( ' Project Heathrow ' for short ) was set up to examine how expansion at Heathrow could best be accomplished within the constraints of the stringent environmental limits the White Paper required . A provisional assessment indicates that increased usage of the existing runways could be realised without increasing the number of people affected by noise if ' mixed mode ' operations ( the simultaneous use of both runways for arrivals and departures ) are phased in gradually as noisier aircraft are retired . Indications ahead of the Project Heathrow environmental assessment indicate that increased noise and deterioration in air quality are likely to significantly constrain traffic using a new third runway . These issues are to be addressed as part of a three @-@ month consultation beginning in December 2007 , and considerable opposition is being mobilised against the expansion of Heathrow . 
