Airport air quality is influenced by traffic mainly. These are emissions from road traffic and aircraft. A measurement campaign on the airport Budapest was performed to investigate airport air quality and to identify major sources of air pollutants and to assess air quality for this airport. At four different locations, concentration of CO, CO2, NO, NO2 and PM10 as well as meteorological parameters were measured simultaneously. Measurement methodologies were classical in-situ techniques and open-path techniques (DOAS and FTIR). Highest concentrations were found during low wind speed conditions downwind of the airport. To quantify emissions on the airport, inverse dispersion modelling with a Bayesian approach was used on the basis of hourly averaged concentration measurements. Single emissions rates were highest for a car park, while for the whole campaign, aircraft emissions on the taxiway around terminal 2 are most important. Similar levels of emissions are reached for the car park and the freight area. Even though the most important source for NO x on an airport, starting aircrafts, were not considered during this investigation, the results reveal, that dealing with air quality on airports, all sources of NOx are important, and not only aircrafts.