Sweeney, B P; Yardley, R E; Butterfield, D M (2006) CPEA 28: airborne particulate concentrations and numbers in the United Kingdon (phase 2) - annual. NPL Report. DQL-AS 031

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Abstract

The annual audit round for the Airborne Particulate Network was carried out during June 2006, 12 months after the previous audits. Their main purpose is to carry out instrument checks and calibrations so that data ratification can account for corrections for instrument drift throughout the year, and, more generally, greater confidence can be placed on the ratified data. The audits also allow for assessment of the site infrastructure and operator competence.
All instruments were operational during the audit round except for the SMPS analysers, and the automatic nitrate analyser at Belfast. The SMPS instruments had not been operational for several months due to their age and the fact that they are no longer supported by the manufacturer. Defra had been kept aware of the situation and replacement SMPS instruments are planned.
Full audits were carried out on all operational instruments. This included checking for leaks and calibrating flow rates; performing zero/blank tests; and calibration, using certified gas standards and an aqueous calibration for the automatic nitrate analysers. The audit results will be used together with the 2005 audit results to ratify the Network data.
No significant problems were found with the condensation particle counters or the daily sulphate samplers.
Both the continuous nitrate and the continuous carbon analysers give complicated results that reduce confidence in the ratified data from these instruments. These need to be investigated more fully in future work.
Some other issues that should be highlighted are:
There is an issue with safety at the new Harwell site. Access to the roof of the building is via an unstable temporary staircase and the local site operator is unable to reach the sampling heads from this staircase. NPL is working with Netcen to arrange a safe alternative.
The condensation particle counter at Birmingham is situated beneath overhanging trees. NPL will take steps to address this problem and will report to Defra at a later date.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	DQL-AS 031
Subjects:	Environmental Measurement Environmental Measurement > Air Quality and Airborne Particulates
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/3581

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