Probing the charge state of ambient and indoor aerosols

Electrostatic charge on aerosols plays a significant role in global air pollution, in pollution control technologies and in industrial aerosol processes. Charge can influence the behaviour of particles as they are transported around at global and micro scales. It influences how particles coagulate and can affect how likely they are to deposit within our lungs. In industrial processes the transport and generation of powders can lead to very high levels of charge being built up on particles and similar effects are observed within vacuum cleaners. In filtration processes electrostatic charge is often employed to improve efficiency of filter media by influencing both the charge on the particles and the charge on filter fibres.

Fundamental understanding of the charge state of different sources of aerosols, i.e. the distribution of charge on particles of different sizes, and the interactions between particles in ambient and indoor environments could lead to improvements in designing pollution control technologies, including filtration and separation systems. Therefore, there is a need to develop measurement tools to effectively and quickly measure the charge state of aerosols.

This PhD project aims to:
1. Develop novel measurement techniques for aerosol charge state that can be applied to a wide range of aerosol types, sizes and species.
2. Use experiments to quantify and evaluate the charge state of different aerosols that are emitted from different sources, which can be found in different indoor and ambient environments. Measure how charge states can evolve due to particle interactions.
3. Develop new modelling tools utilising Computational Fluid Dynamics that account for particle charge state, recombination and charge decay effects that occur with different aerosols in different environments. The model outputs will be compared to the earlier experimental work to understand the physical phenomena that affect charge state that could go on to inform the design of air cleaning devices.

Relevant EPSRC research areas: Analytical science, Particle technology, Sensors and instrumentation

Aerosol science has a significant impact on a broad range of disciplines, extending from inhaled drug delivery, to combustion science and its health impacts, aerosol assisted routes to materials, climate change, and the delivery of agricultural and consumer products. Estimates of the global aerosol market size suggest it will reach $84 billion/year by 2024 with products in the personal care, household, automotive, food, paints and medical sectors. Air pollution leads to an estimated 30-40,000 premature deaths each year in the UK, and aerosols transmit human and animal infections. More than 12 million people in the UK live with lung disease such as asthma, and the NHS spends ~£5 billion/year on respiratory therapies. Many of the technological, societal and health challenges central to these areas rely on core skills and knowledge of aerosol science. Despite this, an Industrial Workshop and online survey (held in preparation for this bid) highlighted the current doctoral skills gap in aerosol science in the UK. Participating industries reported that only 15% of their employees working with aerosol science at doctoral-level having received any formal training. A CDT in aerosol science, CAS, will fill this skills gap, impacting on all areas of science where core training in aerosol science is crucial.

Impact on the UK aerosol community: Aerosol scientists work across governmental policy, industrial research and innovation, and in academia. Despite the considerable overlap in training needs for researchers working in these diverse sectors, current doctoral training in aerosol science is fragmentary and ad hoc (e.g. the annual Fundamentals of Aerosol Science course delivered by the Aerosol Society). In addition, training occurs within the context of individual disciplines, reinforcing artificial subject boundaries. CAS will bring coherence to training in the core physical and engineering science of aerosols, catalysing new synergies in research, and providing a focal point for training a multidisciplinary community of researchers. Working with the Aerosol Society, we will establish a legacy by providing training resources for future researchers through an online training portal.

Impact on industry and public-sector partners: 45 organisations have indicated they will act as CAS partners with interests in respiratory therapies, public health, materials manufacturing, consumer and agricultural products, instrumentation, emissions and environment. Establishing CAS will deliver researchers with the necessary skills to ensure the UK establishes and sustains a scientific and technical lead in their sectors. Further, it will provide an ideal mechanism for delivering Continuing Professional Development for the existing workforce practitioners. The activity of CAS is aligned to the Industrial Strategy Challenge Fund (e.g. through developing new healthcare technologies and new materials) and the EPSRC Prosperity Outcomes of a productive, healthy (e.g. novel treatments for respiratory disease) and resilient (e.g. adaptations to climate change, air quality) nation, with both the skilled researchers and their science naturally translating to long-lasting impact. Additionally, rigorous training in responsible innovation and ethical standards will lead to aerosol researchers able to contribute to developing: regulatory standards for medicines; policy on air quality and climate geoengineering; and regulations on manufactured nano-materials.

Public engagement: CAS will provide a focal point for engaging the public on topics in aerosol science that affect our daily lives (consumer products, materials) through to our health (inhalation therapeutics, disease transmission and impacts of pollution) and the future of our planet (geoengineering). Supported by a rigorous doctoral level training in aerosol science, this next generation of researchers will be ideally positioned to lead debates on all of these societal and technological challenges.