Relative contributions from traffic and aircraft NOx emissions to exposure in West London

An air dispersion model, ADMS-Urban, was used to estimate temporal and spatial contributions to NOx concentrations from aircraft and traffic around Heathrow airport in West London. Special attention was devoted to the modelling of aircraft releases at different heights. Although emissions associated with traffic are smaller than those associated with aircraft, their impact at different locations around the airport, where people are exposed to air pollution, was found to be larger. It was also found that only the concentration levels on timescales of a few hours were relevant in terms of exposure. Integration of this kind of data may prove useful to identify more closely the likely exposure impacts to local populations caused by different pollution sources. In addition, a preliminary comparison of the results of the model with data available at a monitoring station nearby the airport was subsequently performed. Discrepancies between monitoring data and the model are discussed, suggesting that the aircraft contribution is overestimated and the traffic contribution underestimated.