Aerosol science, the study of airborne particles from the nanometre to the millimetre scale, has been increasingly in the public consciousness in recent years, particularly due to the role played by aerosols in the transmission of COVID-19. Vaccines and medications for treating lung and systemic diseases can be delivered by aerosol inhalation, and aerosols are widely used in agricultural and consumer products. Aerosols are a key mediator of poor air quality and respiratory and cardiac health outcomes. Improving human health depends on insights from aerosol science on emission sources and transport, supported by standardised metrology. Similar challenges exist for understanding climate, with aerosol radiative forcing remaining uncertain. Furthermore, aerosol routes to the engineering and manufacture of new materials can provide greener, more sustainable alternatives to conventional approaches and offer routes to new high-performance materials that can sequester carbon dioxide. The physical science underpinning the diverse areas in which aerosols play a role is rarely taught at undergraduate level and the training of postgraduate research students (PGRs) has been fragmentary. This is a consequence of the challenges of fostering the intellectual agility demanded of a multidisciplinary subject in the context of any single academic discipline. To begin to address these challenges, we established the EPSRC Centre for Doctoral Training in Aerosol Science in 2019 (CDT2019). CDT2019 has trained 92 PGRs with 40% undertaking industry co-funded research projects, leveraged £7.9M from partners and universities based on an EPSRC investment of £6.9M, and broadened access to our unique training environment to over 400 partner employees and aligned students. CDT2019 revealed strong industrial and governmental demand for researchers in aerosol science. Our vision for CDT2024 is to deliver a CDT that 'meets user needs' and expands the reach and impact of our training and research in the cross-cutting EPSRC theme of Physical and Mathematical Sciences, specifically in areas where aerosol science is key. The Centre brings together an academic team from the Universities of Bristol (the hub), Bath, Birmingham, Cambridge, Hertfordshire, Manchester, Surrey and Imperial College London spanning science, engineering, medical, and health faculties. We will assemble a multidisciplinary team of supervisors with expertise in chemistry, physics, chemical and mechanical engineering, life and medical sciences, and environmental sciences, providing the broad perspective necessary to equip PGRs to address the challenges in aerosol science that fall at the boundaries between these disciplines. To meet user needs, we will devise and adopt an innovative Open CDT model. We will build on our collaboration of institutions and 80 industrial, public and third sector partners, working with affiliated academics and learned societies to widen global access to our training and catalyse transformative research, establishing the CDT as the leading global centre for excellence in aerosol science. Broadly, we will: (1) Train over 90 PGRs in the physical science of aerosols equipping 5 cohorts of graduates with the professional agility to tackle the technical challenges our partners are addressing; (2) Provide opportunities for Continuing Professional Development for partner employees, including a PhD by work-based, part-time study; (3) Deliver research for end-users through partner-funded PhDs with collaborating academics, accelerating knowledge exchange through PGR placements in partner workplaces; (4) Support the growth of an international network of partners working in aerosol science through focus meetings, conferences and training. Partners and academics will work together to deliver training to our cohorts, including in the areas of responsible innovation, entrepreneurship, policy, regulation, environmental sustainability and equality, diversity and inclusion.

Air pollution causes 29,000 pre-mature death and cost the economy £20 billion per year in the UK alone. A majority of these impacts are associated with Vulnerable Groups (VGs), who are most strongly affected by air pollution with up to ca. 12 life years lost for the individual. Children (VGI) & people with pre-existing medical conditions (VGII) are of particular concern in terms of long-term health, societal & economic impacts. Despite this, most of the efforts in air quality improvement focuses on the general population and outdoor exposure. This leads to major gaps in understanding their exposure to key air pollutants (particularly PM1, ultrafine particles and VOCs), health risks & economic consequences, and the key challenges and mitigation options for these Vulnerable Groups. This network will be the first step towards establishing practical air pollution solutions for Vulnerable Groups tackling a major health & economic challenge that cannot be resolved within traditional, often segregated air quality communities. It will build a new truly cross-disciplinary and self-sustaining network bringing academics with a wide spectrum of expertise ranging from economics via psychology & engineering to indoor & outdoor air pollution science together with key industrial, governmental and NGO stakeholders. The long-term vision of the network is to develop innovative & cost-effective behaviour and technology interventions to reduce the Vulnerable Groups' future air pollution exposure, improve health & directly implement these interventions through policy advice, planning, and business innovations. The network will be composed of 8 streams (6 Work Packages (WPs) & 2 Scoping Groups (SGs)). Collectively, it will review the state-of-the-art in our understanding on (i) the VGs' air quality challenges at the indoor/outdoor interfaces, (ii) behaviour interventions to reduce pollution exposure, (iii) technology interventions at indoor/outdoor interfaces, (iv) health benefits of interventions, and (v) economic benefits of these interventions. They will also identify the future research priorities, particularly in terms of cross-disciplinary challenges, policy & business engagement. Each of the WPs will be co-led by academics and non-academic stakeholders, with support from a core group composed of Co-Is/stakeholders with relevant expertise and their institutional critical mass. Importantly, engagement will be co-led by the government-supported Connected Places Catapult (CPC). This will catalyse and enhance the existing engagement with decision makers and business partners to align our future research with their practical priorities. The network will carry out an initial scoping study to longlist wider contributors that can contribute expertise to networks and then shortlist key members to be directly involved in the network. The network will generate abundant opportunities for within- and cross-disciplinary exchanges through network meetings, direct face-to-face meetings with stakeholders (e.g. local authorities or key industrial partners), writing retreats, social media and webinars. The network will also illustrate potential solutions via a pilot study informed by insight gained in the engagement (WPs 1-6) as part of the interdisciplinary Cross-WP Scoping Group and the Cross-Network Scoping Group will liaise with the other five networks to link outcomes and establish opportunities for future bid development. This work will leave a lasting legacy of a collaborative, interdisciplinary network that will drive forward research and innovation in delivering the air pollution solutions for vulnerable groups, improving their health, and reducing the cost to the NHS and the economy.