Ultrafine particles are smaller than 100 nanometres in diameter, making them significantly smaller than the more commonly considered PM10 or PM2.5, which measure up to 10,000 and 2,500 nanometres respectively. Their small size means that UFP can penetrate far more deeply into the lungs and can even enter the bloodstream.
Individual measurements have shown for some time that air pollution from UFP is considerably higher in the vicinity of airports. It was not previously known how pollution is distributed across a large area and which sources are responsible for it. The developed model can calculate pollution concentrations surrounding an airport at distances of 30 km if corresponding data is available. The model description for the 2015 annual average shows that the ultrafine particle concentration at and around the Frankfurt/Main airport is significantly elevated, as do measurements at various different locations.
The main source of UFP was identified as turbine emissions during ground operations, with a share of 90 per cent of the non-volatile UFP. Ground taxiing of aircraft accounts for half of this, while the other half is due to take-off and landing operations. The modelling showed how much the airport site determines the ultrafine particulate load of the surrounding area. At a distance of one kilometre from the airport perimeter, the airport accounts for up to 25 per cent of total UFP. Road traffic accounts for just about five per cent.
Reducing the sulphur content of kerosene could drastically cut UFP emissions. Runway towing (electric, if possible) can be executed without operating aircraft engines. Engine technology also determines particle emissions. Appropriately designed emissions-based landing fees could provide important incentives to reduce emissions.
The models used in the study are not yet able to capture all details. The results therefore show a different seasonal pattern than the measurements. The investigations lead to the conclusion that substantial further developments are necessary in order to model exposure to ultrafine particles with sufficient accuracy. Databases for calculating emission quantities from sources and models apply different definitions for particle classifications. Models also cannot yet adequately address the formation and conversion of ultrafine components to calculate total UFP emissions, whereas measurements record the sum of volatile and non-volatile components. To compare model results and measurements, a measurement technique should therefore be used that can quantify volatile and non-volatile components of ultrafine particulate matter in the different size classes. A follow-up project on ultrafine particle loads at Berlin's airports is planned (ULTRAFLEB, 2020 – 2024, FKZ 3720 52 201 0).