Williams, K R; Bradshaw, C P; Ciupek, K; Singh, G K; Tompkins, J T; Brown, A S; Butterfield, D M; Derby, A T; Farooq, M H; Harvey, R N; Kazemimanesh, M; Longhurst, B A; Kean, M N; Robins, C C; Schmeer, J L; Tipler, J M; Tomson, M; Walker, D J W; Priestman, M D S; Tremper, A H; Ek, D E B; Green, D C; Punter, P B (2026) UK Particle Concentrations and Numbers and Black Carbon Networks: Annual report 2025. NPL Report. ENV 68

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Abstract

The National Physical Laboratory (NPL) is contracted to manage the UK Particle Concentrations and Numbers (PCN), and Black Carbon (BC) Networks (henceforth referred to as the Network). The Network measures and reports concentrations and chemical composition of particles in ambient air across the UK, with a focus on PM2.5 (particulate matter with an aerodynamic diameter < 2.5 µm).

This report was prepared by NPL and the Environmental Research Group at Imperial College London as part of the Network contract. The contract is managed by the Environment Agency on behalf of the Department for the Environment, Food and Rural Affairs and the Devolved Administrations: the Northern Ireland Executive, the Scottish Government and the Welsh Government.

This annual report contains:

- a summary of the Network structure, its operation, and quality procedures;
- descriptions of the instruments used on the Network;
- the data capture recorded for each instrument;
-time series plots of all ratified Network data in 2025;

and, where applicable:

- plots of diurnal, weekly, and monthly variations in ratified Network data in 2025;
- plots of the long-term trends in ratified Network data;
- comparisons between pollutants measured by the Network;
- activities associated with the UK PM2.5 MEP (monitoring expansion programme), to provide additional particulate matter (PM) speciation data to enhance the measurement evidence base associated with the PM2.5 targets from the Environmental Targets (Fine Particulate Matter) (England) Regulations 20231.

In 2025, the Network operated at 27 UK monitoring sites with a mixture of site classifications: rural background, urban background, and urban traffic.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	ENV 68
Subjects:	Environmental Measurement > Air Quality and Airborne Particulates
Divisions:	Atmospheric Environmental Sciences
Identification number/DOI:	10.47120/npl.ENV68
Last Modified:	22 Sep 2026 13:43
URI:	https://eprintspublications.npl.co.uk/id/eprint/10548