In recent years computer models have been developed that make it possible to calculate the day‐night levels around airports at a reasonable cost. Determining the number of people exposed to various noise levels has always been a time‐consuming and expensive operation because it required extensive manual data gathering. This paper discusses how the output from an airport noise prediction model (NOISEMAP) has been modified so that the output is suitable as input into a commercially available computer program that automatically collects demographic data within an arbitrary polygon. A discussion of how the information produced can then be used in environmental impact reporting is given. This includes using the fractional impact method for defining impact.