Aircraft engines emit pollutants that degrade the air quality around airports, which may affect the health of local residents and employees at the airport. Specifically, nanoparticles emitted from gas turbine engines comprise soot aggregates, sulphur compounds, semi-volatile organic carbon and metallic ash. As the aircraft engine jet cools and mixes with the surrounding atmosphere, nucleation and condensation processes lead to a rapid growth in nucleation mode particles and condensation of semi-volatile compounds onto non-volatile soot aggregates. Aircraft nanoparticle emissions are characterised by their small size (<60 nm) relative to other combustion sources, e.g. road transport. They may therefore have particular health consequences that are currently under-studied and not well understood. Few studies have conducted in-vitro toxicology tests to evaluate the effects on human bronchial epithelial cells to exposure to aircraft soot emissions from aircraft engines. Much more work is needed to understand the different effects of aircraft nanoparticles and the role of their different properties and chemical constituents.

This project aims to contribute to the understanding of the health impacts pathways of nanoparticles by developing and experimental methodology to test cellular responses to different sized nanoparticles and chemical compositions. The specific objectives of the project are to:

1. Review the literature on aircraft nanoparticle emissions, nanoparticle measurements near airports, and health impacts of different types and sources of combustion aerosols, including cellular response studies.
2. Develop laboratory source of soot particles that can be used to generate a tuneable surrogate aircraft aerosol in terms of particle size distribution and morphology, chemical composition and different coatings, and atmospheric ageing and oxidation. The soot source will be based on a burner design that has been used as a surrogate for aircraft soot particles before, and additional features such as organic carbon coatings and atmospheric ageing will be developed.
3. Use the surrogate soot source to design and conduct a comprehensive matrix of experiments to evaluate cellular responses to particle size and morphology, chemical composition of coatings, and atmospheric ageing. For example, aerosol classifiers could separate particular particle sizes before deposition on the cell culture to control for the effects of particle size. Similarly, particles could be coated with different materials, or have their coating removed by the use of a catalytic stripper. These methods are already established and involve exposure of primary human lung cells to increasing concentrations of the particles and determination of cell viability (MTT/LDH/apoptosis assays), mediator production (ie pro-inflmmatory responses; ELISA assays), oxidative stress (ROS measurement), mitochondrial integrity (mitotracker), cellular antioxidant depletion (GSH oxidation) and particle uptake. Positive controls (eg ZnO nanoparticles) with known toxicity will be tested in parallel.
4. Evaluate potential health impacts of aircraft nanoparticle emissions around airports using existing evidence and new modelling works to understand how health risks may vary with distance from the airport, and other factors such as weather conditions.
Novel engineering/physical sciences content
Development of particle technology techniques to generate soot nanoparticles with different coatings, sizes, shapes
Health impacts of pollution from engineering systems, specifically aircraft engine emissions. This could inform development of air quality standards.

Research council themes
Relevant EPSRC themes: Engineering, Energy
Relevant EPRSC research areas: Analytical science, Built environment, Infrastructure and urban systems, Particle technology, Sensors and instrumentation