Assuming the weak velocity-to-heat release rate relationship prove valid, a significant increase in the heat release rate of a fire will be required to cause any notable change in the velocity of the smoke wave. This is especially true when considering the short time scale (50 to 90 seconds) necessary for the smoke to transit a relatively long (30 m) corridor. Based on these data, it is reasonable to assume that even a relatively small fire (200 to 500 kW) could prevent the use of a long corridor as an escape route in less than 2 or 3 minutes.