Airport air quality is influenced by traffic mainly. Near runway the aircrafts are the main source. The quantification of
these emission sources requires remote sensing methods because the airport operations should not be disturbed. DOAS is
used in open-path mode to detect continuously NO<sub>2</sub> cross the runway during nearly one year. Those runway emission
studies were performed for the first time.
During the measurement campaign these findings were compared with corresponding aircraft taxiway emission
The concentration measurements of CO<sub>2</sub> which are necessary to calculate emission indices are provided by open-path
FTIR spectrometry. Aircraft emission indices of CO, NO and NO<sub>2</sub> could be determined at taxiway only.
Open questions and required further developments will be discussed.
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, CO<sub>2</sub>, NO, NO<sub>2</sub> 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<sub>x</sub> on an airport, starting aircrafts, were not considered during this investigation, the results reveal, that
dealing with air quality on airports, all sources of NO<sub>x</sub> are important, and not only aircrafts.
Air pollutant emission rates of aircrafts are determined with test bed measurements. Regulations exist for CO<sub>2</sub>, NO, NO<sub>2</sub>, CO concentrations, the content of total unburned hydrocarbons and the smoke number, a measure of soot. These emission indices are listed for each engine in a data base of the International Civil Aviation Organisation (ICAO) for four different Air pollutant emission rates of aircrafts are determined with test bed measurements. Regulations exist for CO2, NO, NO2, CO concentrations, the content of total unburned hydrocarbons and the smoke number, a measure of soot. These emission indices are listed for each engine in a data base of the International Civil Aviation Organisation (ICAO) for four different thrust levels (Idle, approach, cruise and take-off). It is a common procedure to use this data base as a starting point to estimate aircraft emissions at airports and further on to calculate the contribution of airports on local air quality. The comparison of these indices to real in use measurements therefore is a vital task to test the quality of air quality models at airports. Here a method to determine emission indices is used, where concentration measurements of CO<sub>2</sub> together with other pollutants in the aircraft plume are needed. During intensive measurement campaigns at Zurich (ZRH) and Paris Charles De Gaulle (CDG) airports, concentrations of CO<sub>2</sub>, NO, NO<sub>2</sub> and CO were measured. The measurement techniques were Fourier-Transform-Infrared (FTIR) spectrometry and Differential Optical Absorption Spectroscopy (DOAS). The big advantage of these methods is that no operations on the airport are influenced during measurement times. Together with detailed observations of taxiway movements, a comparison of emission indices with real in use emissions is possible.
At the beginning of an air pollution event, pollutants are emitted into the atmosphere by a variety of sources. The knowledge of the emissions of every source is inevitable to carry out adequate reduction measures. Sometimes, the estimation of source strengths from afar is necessary due to the lack of accessibility to the source (e.g.: aircraft in use) or due to the diffuse character of the source (e.g. area sources). Source strengths and concentration measurements are connected by the transport of the pollutant, which can be estimated using a dispersion model. The underlying idea to determine the source strength is to run the dispersion model varying the input parameters as long as needed to obtain the least possible difference of measured and modelled concentrations. The model input is then assumed to be the best estimation of the emission rates. Assuming a passive pollutant, the transport and dispersion can be condensed into a set of linear equations and hence, linear algebra can be used to solve for the source strength (e.g. Singular Value Decomposition). The advantage of concentration measurements along a horizontal path (e.g. by FTIR, DOAS) is to reduce the degree of uncertainty regarding the horizontal dispersion. So the main interest of the modelling approach is to estimate the amount of vertical dispersion that accounts for the dilution of the pollutants. Applying this method to a real case with highly heterogeneous source characteristics in time and space, measurements at an international airport were performed. Some results of these measurements are presented here.