Committee publication · Correspondence · 16 September 2025 · HC 1284

Letter to the Secretary of State for Environment, Food and Rural Affairs relating to pollution from highway run-off, 16 September 2025

From: Environmental Audit Committee

Inquiry: National Highways and environmental sustainability

Summary

The Environmental Audit Committee writes to the Secretary of State for Environment, Food and Rural Affairs following a 3 September 2025 evidence session on National Highways and environmental sustainability. The committee raises concern that highway run-off pollution—containing microplastics, hydrocarbons, and toxic metals—receives insufficient political and regulatory attention compared to sewage pollution. It urges the government to address urban diffuse pollution in the forthcoming White Paper following the Cunliffe review and to clarify discussions with the Department for Transport on adopting Euro 7 emissions standards.

Key findings

  • Highway run-off pollution containing microplastics, hydrocarbons, and toxic metals is not receiving adequate regulatory attention compared to sewage and agricultural pollution
  • Witnesses characterised highway pollution as 'flying under the radar' and the 'poor cousin' in terms of political attention and funding
  • National Highways has accelerated mitigation work following the predecessor committee's 2022 water quality report, but a gap remains in monitoring and regulation
  • Particulate matter from vehicle brakes and tyres will persist and potentially increase with electric vehicle uptake, despite other pollution reductions
  • All witnesses agreed adoption of EU Euro 7 emissions standards across the UK would positively reduce highway-related pollution

Tone

Critical

Topics

water-pollutionenvironmental-regulationtransport-emissionsurban-environmentair-quality

Key actors

Emma Reynolds MP, Toby Perkins MP, Catherine Moncrieff, Jo Bradley, National Highways, Chartered Institution of Environmental and Water Management (CIWEM), Stormwater Shepherds, Department for Transport

Notable line

… this issue of highway pollution is still flying under the radar " …

Key Quotes

… this issue of highway pollution is still flying under the radar " , and is the "poor cousin" in terms of political attention and funding when compared to sewage pollution
Catherine Moncrieff, Head of Policy and Engagement at the Chartered Institution of Environmental and Water Management (CIWEM) · evidence on relative policy neglect of highway pollution
… highway run-off containing microplastics, hydrocarbons and toxic metals, which Jo Bradley, Director of Operations UK at Stormwater Shepherds …
Jo Bradley, Director of Operations UK at Stormwater Shepherds · describing the composition and impact of highway pollution
… it is clear that compared to other types of water pollution, such as sewage or agricultural pollution, there is a gap in monitoring and regulation
Environmental Audit Committee · committee's assessment of the regulatory landscape
We urge you to ensure that this type of pollution, and how it is monitored and regulated, is properly considered in the forthcoming White Paper. We agree with our witnesses that failure to do so would be a missed opportunity.
Toby Perkins MP, Chair, Environmental Audit Committee · requesting government action on urban diffuse pollution in upcoming legislation
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Source · parliament.uk record ↗

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