Project highlights

  • Design of experiments to simulate interactions between natural and anthropogenic particles along transport pathways in air
  • Use and development of optical measurement techniques to quantify and analyse particle interactions
  • Application to understanding the fate and distribution of substances such as plastic waste and organic materials in the environment.


Air pollution can reduce the quality and length of life for humans.  It is estimated that in 2019 around 90% of the world population was exposed to concentrations of fine particles (less than 2.5 µm diameter) that exceeded World Health Organisation air quality guidelines.  The sources of these fine particles can be natural, for example caused by wind erosion of agricultural lands and dust storms, or anthropogenic, for example resulting from the burning of fuelwood and road traffic emissions.  Particles can be directly released into the atmosphere such as during a volcanic eruption, or may be deposited on surfaces and then resuspended into the air.

This project focuses on the resuspension of particles where the action of moving air on loose particles can cause them to move.  Particles on natural or anthropogenic surfaces may become dislodged and move across the surface, or be lifted in to the air along ballistic trajectories.  Particles returning to the surface may impact, dislodge and eject more particles into the flow.  As particles move they interact with each other via in-air collision and impact other objects such as surfaces (e.g. rocks, roads) which can cause them to breakdown by abrasion or wear creating smaller particles.  It is these very small particles that dominate air pollution.  The impact of air density, which varies with temperature and altitude, and particle density as determined by the material composition on how particles and surfaces interact is very poorly understood but has the potential to substantially change the rate at which fine polluting particles are produced and their dispersal.  There is a need for better understanding and prediction of fine particle production, characteristics (such as shape and size) and distribution to determine their impact on, and implications for environmental systems.  This includes not only the atmosphere but also terrestrial and marine ecological systems when particles are deposited.

Photo of the movement of microplastics about 0.2 mm diameter in air showing the trajectory and relative velocity of particles.

Figure 1: The movement of microplastics about 0.2 mm diameter in air where red indicates the trajectory and relative velocity of particles.


Loughborough University


  • Climate and Environmental Sustainability
  • Dynamic Earth


Project investigator

Prof. Joanna Bullard, Geography, Loughborough University ([email protected])




Co-I: Prof. Adrian Spencer, Aeronautical and Automotive Engineering, Loughborough University ([email protected])

How to apply


This project will involve laboratory simulations of the interaction of different types of particles under a range of environmental conditions.  A key component will be using optical measurement techniques to track particle trajectories and determine impact and ejection velocities and angles and energy partitioning for given collisions.  The effect of atmospheric transport and breakdown on particles will be examined using scanning electron microscopy and associated characterisation techniques.  There are limited data with which to test and refine models of particle entrainment, motion and breakdown and as a result, existing models can be deficient in providing a realistic and validated representation of particle dynamics.  There is scope for the student to link data and modelling approaches together by using the former to test, calibrate and validate the latter.

Work with the project collaborator has the potential to add a wind tunnel experiment component to the project.

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

Training will be provided in experimental design and optical measurement techniques including particle tracing and scanning electron microscopy.  The student will have support to develop appropriate programming and analysis skills.

Partners and collaboration

There is a strong link between Loughborough University and Trent University, Peterborough, Ontario, Canada which has the only purpose built wind tunnel for the study of wind-blown particles.  There will be an excellent opportunity to collaborate with researchers at Trent Environmental Wind Tunnel.

Further details

For further information about this project, please contact Prof Jo Bullard ([email protected]). For general information about CENTA and the application process, please visit the CENTA website: For enquiries about the application process, please contact the School of Social Sciences & Humanities ([email protected]).

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Possible timeline

Year 1

Familiarisation with literature and development of programming skills.  Initial pilot experiments to test methodology and data analysis techniques.  Focusing of study by particle type (natural and/or anthropogenic) and environment.

Year 2

Main set of experiments and data analysis including potential for work at Trent Environmental Wind Tunnel.

Year 3

Detailed analysis, integration and interpretation of all experiments, writing up.

Further reading

Gordon, M., McKenna Neuman, C. (2011) ‘A study of particle splash on developing ripple forms for two bed materials’ Geomorphology, 129, 79-91.

Liu, C., Kiger, K. (2022) ‘The application of apertured filter method to the simultaneous measurement of particle-turbulence interaction in dilute suspension layer under oscillatory sheet flows’.  20th International Symposium on Application of Laser and Imaging Techniques to Fluid Mechanics, Lisbon, Portugal, July 11-14, 2022.

O’Brien, P., McKenna Neuman, C. (2018) ‘An experimental study of the dynamics of saltation within a three-dimensional framework’.  Aeolian Research, 31, 62-71.


Experimental design is such that a single person can safely set up and run experiments for this project minimising contact with others.  Movement restrictions may limit the collection of new materials to test in experiments but there is a sufficiently large archive of suitable sediments and materials available that work could still continue.  It is unlikely that the project would be substantially affected.