Understanding UK airborne microplastic pollution: sources, pathways and fate

Microscopic plastic debris, known as microplastics, are a complex class of particulate pollutants. They originate from degraded plastic litter and human activity, such as washing synthetic clothes or driving with synthetic tyres, and are ubiquitous across habitats worldwide. Microplastics comprise different plastic types and shapes, span several orders of magnitude in size, and harbour harmful chemicals and microbes. They have shown to cause biological harm in aquatic and terrestrial species in laboratory studies, leading the European Commission to recommend measures to minimise their release. Recent evidence demonstrating their presence in outdoor dust suggests that microplastics can be airborne, presenting air as a novel vehicle for dispersion and entry into the wider environment. This also raises concern for human exposure to microplastics via inhalation. Whether they occur in sizes small enough to enter the central and deep airways has not been measured but is imperative for future studies on the impacts of microplastics on population health. Considering their potential sources, higher levels are anticipated in urban environments, presenting both a greater population exposure and a source to pristine and sensitive habitats.

This project aims to assess the extent and fate of airborne microplastic pollution in the UK. This will include examining microplastic sources, size-distribution, transport, and fate, which will be achieved through the following objectives: development of a standardised work flow and analytical methods for microplastics in different types of air samples (O1); measurement of atmospheric deposition loadings for microplastics in different environments (O2); understanding the seasonal variation of microplastic deposition (O3); quantification of size distributions for airborne microplastics in urban and rural environments (O4); identification of the sources (point, linear, area) of airborne microplastics (O5); an indication of whether microplastics are vertically mixed >150 m (O6); and an evaluation of the environmental fate of microplastics in a multi-media study (O7).

Microplastic pollution is growing exponentially as a field, yet the atmosphere remains understudied. This is the first large UK project to address airborne microplastics and the first to measure microplastics in health-relevant size fractions, addressing two key knowledge gaps. Evidence of the various sources and levels of airborne microplastics will provide a baseline to assess the efficacy of efforts to minimise release and indicate whether it is necessary to incorporate into future air quality monitoring programmes and deposition networks. The associated health effects of particulate matter (PM) are well-established and primarily associated with road transport and fuel burning emissions. As global pressure to reduce such emissions increases, PM composition is likely to shift. In combination with a predicted increase in plastic use, especially in the textile sector (4%/year), the proportional concentration of airborne microplastics will become increasingly important. It is therefore timely to establish baseline knowledge of airborne microplastic burdens.

Identified beneficiaries of this research include: policymakers across organisational tiers, including transnational, inter- and intra-governmental bodies (B1); plastic feedstock, fibre, textile, clothing and fashion industries (via Industry Action on Microfibres; The Microfibre Consortium); (B2); Key Stage 3 pupils, their parents and teachers (B3); and members of the wider public (B4). To maximise impact, the following goals (G) have been identified:

G1: Generate evidence on the various sources of airborne microplastics (point, linear and area) to differentiate between sources (e.g. road, industrial, marine) and thus help prioritise policy measures to prevent emissions. Stakeholders: B1 (e.g. EC, DEFRA, EA, DfT) - B4. The evidence generated will influence public policy and legislation at the national and international level to minimise microplastic emissions. Short term, we will contribute to committee reports and recommendations. Longer term, it is envisaged this will influence regulations to reduce microplastics release. These measurements will produce a baseline against which future policy impacts can be assessed. This will contribute toward a sustainable future, protecting the environment, reducing environmental impacts and improving health and wellbeing.
G2: Produce evidence on microplastic sources and emissions in London as an example of intense human activity on microplastic concentrations in complex urban locations. Stakeholders: B1 (regional government (Greater London Authority) and individual local authorities, national agencies working in London, similar organisations in other international cities) - B4. The evidence generated will influence public policy and legislation at a local level to minimise microplastic emissions. These measurements will produce a baseline as in G1. Local, rather than national, action can be more quickly enacted, targeted and effective. It can make use of established relationships between local government and employers locally (e.g. schools, government, NHS) and the direct contracts with the waste recycling industry.
G3: Provide evidence on the polymer types and potential sources of contaminating microplastic fibres to direct whole-system innovation towards sustainability. Stakeholders: B1 - B2 (within IAM, e.g. Unilever, Primark, Arcadia). We will maximise the opportunity for evidence to catalyse the development of fibres and fabric structure which are more resistant to shedding or of sustainable, low-impact textiles. Knowledge transfer will build capacity in these organisations to change cultural 'fast fashion' practices to enhance sustainability.
G4: Increase awareness of the need for development and issuance of guidelines for plastics (including textiles), waste management, tyres and other related industries. Stakeholders: B1 - B2. We will use the data generated in the short-term to enable the development of a set of industry recommendations for best-practice solutions to reduce microplastic release in conjunction with IAM.
G5: Reduce microfibre shedding and therefore exposure, benefitting both the wider environment and general population. Stakeholders: B2 - B4. This will benefit both environment and health after the lifetime of the project.
G6: Empower pupils to make observations, collect data and develop their critical thinking. Stakeholders: B3. We will influence students to feel encouraged and excited by science, inspiring a future generation of scientists as soon as these interactions arise.
G7: Evaluate the feasibility of a downstream large-scale citizen science project. Stakeholders: B3.
G8: Increase microplastics awareness and understanding of its broader science. Stakeholders: B3 - B4. This will encourage change in current behaviours and consumer patterns in relation to plastic in the short-term. Longer-term, the resulting reduction of microplastic emissions delivered by the community will contribute to environmental and health preservation.