A spokesman for BAA said it would only increase the number of flights at the airport if it can operate within these limits.
BAA chief executive Colin Matthews said: "We have listened to the many arguments around expansion at Heathrow. Although the economic case remains compelling, we understand that we can only increase the number of flights if we can safeguard levels of noise and air quality. By calling on an independent assessor to scrutinise the airport's performance against these limits, we are providing an uncompromising assurance that we will operate Heathrow Airport within the limits laid down by government. If we don't, the number of flights in and out of Heathrow could be capped."
Critics were not impressed, Liberal Democrat transport spokesman Norman Baker said: "This is a worthless promise, as BAA has to stick to EU emissions limits anyway. It is clearly an attempt to get the new runway in place and then to come back demanding more flights at a later date. The last 15 years have been littered with promises of no more expansion, followed by demands for exactly that."