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Equivalence of UK nitrogen dioxide diffusion tube data to the EU reference method

Butterfield, D; Martin, N A; Coppin, G; Fryer, D E (2021) Equivalence of UK nitrogen dioxide diffusion tube data to the EU reference method. Atmospheric Environment, 262. 118614 ISSN 13522310

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The UK Government’s Department for Environment, Food and Rural Affairs has set up a framework for Local Air Quality Management (LAQM) and Local Authorities widely use nitrogen dioxide (NO2) diffusion tubes for Indicative monitoring for Review and Assessment purposes. The European Union under directive 20/50/EC on ambient air quality and cleaner air for Europe provides data quality objectives both for Indicative and Fixed measurements of NO2.

LAQM diffusion tube measurements across the UK between 2015 & 2019 were analysed to see if they had been providing data of sufficient quality to be classed as Indicative measurements in support of Local Air Quality Management. Bias corrected annual averaged measurements delivered uncertainties compared to the reference method of <±25%, therefore demonstrating that application of the National Bias Adjustment Factors is providing valid Indicative diffusion tube measurements for the UK.

For the period January 2020 to June 2020, the equivalence of the monthly UK Urban NO2 Network (UUNN) diffusion tubes were analysed. The UUNN style diffusion tube is similar to the LAQM style but with the addition of an amorphous polyethylene (PE) filter across the open end of the tube. Results showed that the Network so far meets the EU Directive uncertainty requirement for Fixed measurements (±15%), without the need for slope or intercept correction. Mean NO2 concentrations derived from triplicate UUNN tubes show a much better precision than the triplicate conventional LAQM tubes.

A field determination of the diffusive sampling rate for UUNN tubes was performed at London Marylebone Road, showing that the sampling rate in real world conditions was very similar to that determined in the laboratory.

Diffusion tube data form Belgium and Germany were also analysed for equivalence with the Standard Reference Method to help put the UK results into context.

Item Type: Article
Keywords: diffusive samplin, nitrogen dioxide (NO2), ambient air, equivalence, chemiluminescence analyser
Subjects: Environmental Measurement > Atmospheric Science, Emission and Security
Divisions: Atmospheric Environmental Sciences
Identification number/DOI: 10.1016/j.atmosenv.2021.118614
Last Modified: 08 Sep 2021 13:52
URI: http://eprintspublications.npl.co.uk/id/eprint/9271

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