SUMMARYThe resultsof an air quality impact assessment conducted in 1980, for the proposed development of Stansted airport, Essex, to a capacity of 15 million passengers per annum, are presented. Air pollutant concentrations measured in the vicinity of the airport were found to be low in comparison to ambient air quality guidelines and also when compared with other airports and urban areas.Atmospheric dispersion modelling to predict future emissions and ambient concentrations of air pollutants revealed that air quality standards would be unlikely to be infringed and that concentrations would be generally within the range of those measured at Gatwick airport in 1979.