Tompkins, J; McGhee, E; Ciupek, K; Williams, K; Robins, C; Allerton, J; Quincey, P; Brown, A; Brown, R J C; Green, D; Tremper, A; Priestman, M; Font Font, A (2021) Airborne particulate concentrations and numbers in the United Kingdon: Annual Report 2019. NPL Report. ENV 39

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Abstract

This report was prepared by the National Physical Laboratory (NPL) and the Environmental Research Group (ERG) at King’s College London (KCL) as part of the UK Airborne Particulate Concentrations and Numbers (PCN) contract managed by the Environment Agency (EA), provided on behalf of the Department for the Environment, Food and Rural Affairs (Defra) and the Devolved Administrations (the Scottish Government, the Welsh Government and the Department of the Environment in Northern Ireland). ERG moved from KCL to Imperial College London (ICL) during 2020.

This Annual Network Report for 2019 contains:

A summary of network operations and quality procedures.
Description of the instruments used on the Network.
A graphical presentation of all ratified network data from 2019.
Data capture for each instrument.
Comparison of 2019 data with data from recent years.
The Network operated instruments at four monitoring sites: the London roadside site Marylebone Road, the London urban background site Honor Oak Park, and the rural sites Chilbolton, in south-east England, and Auchencorth Moss, in Scotland.

Weekly measurements of Organic Carbon and Elemental Carbon (OC/EC) in the PM2.5 fraction, required by the European directive 2008/50/EC, continued throughout the year at the two rural sites, Chilbolton and Auchencorth Moss. Daily measurements of OC/EC were changed from the PM10 fraction to the PM2.5 fraction at Honor Oak Park in February 2019, and at Marylebone Road in October 2019. Daily PM10 measurements of OC/EC at Chilbolton were discontinued in October 2019.

Hourly PM2.5 ion chromatography measurements were made at Honor Oak Park throughout the year. The size fraction of similar measurements at Marylebone Road was changed from PM10 to PM2.5 in January 2019. Concentrations of chloride, nitrate, sulphate, sodium, ammonium, potassium, magnesium and calcium ions in ambient air were measured at these sites. An Aerosol Chemical Speciation Monitor (ACSM) operated by ICL at Honor Oak Park provided hourly measurements of ammonium, nitrate, sulphate and organic aerosols in PM2.5.

Hourly total particle number concentrations were measured using condensation particle counters (CPCs) at Chilbolton, Honor Oak Park and Marylebone Road. Particle number size distributions were also measured using scanning mobility particle sizers (SMPSs) at the same sites.

Across 2018 and 2019, the network instruments have switched from sampling PM10 to sampling PM2.5 to align with the shift in focus towards PM2.5 as a more relevant metric for health effects.

Some notable features of the data are:

Annual average EC concentrations at Marylebone Road have decreased rapidly and steadily from around 8 μg m-3 in 2009 to around 2 μg m-3 in 2019. EC at other sites, and OC at all sites, have shown a more gradual decline.
Annual average particle number concentrations at Marylebone Road have remained relatively constant in the range 7,000 to 10,000 cm-3 since the rapid decrease from around 80,000 cm-3 in 2007-2008, which was attributed to the introduction of low sulphur vehicle fuel.
The Network data are available electronically via the Defra UK-Air website

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	ENV 39
Keywords:	Particles, particle number concentration, partical size concentration, ambient air, anions, cations, elemental carbon, organic carbon
Subjects:	Environmental Measurement > Air Quality and Airborne Particulates
Divisions:	Atmospheric Environmental Sciences
Identification number/DOI:	10.47120/npl.ENV39
Last Modified:	08 Nov 2021 09:45
URI:	https://eprintspublications.npl.co.uk/id/eprint/9292