The National Physical Laboratory's (NPL) audit programme for sites in the London and neighbouring air quality networks will be extended in 2007.

We have worked closely with NPL for the last 8 years to improve the quality of measurements. These latest advances ensure a fully accredited audit programme that is adaptable to new measurements technologies and responsive to changes in European standards.

During site audit visits, scientists from NPL undertake extensive testing of instrument performance and site calibration standards. These tests have always replicated those carried out on the UK Automated Urban and Rural Network and form a foundation stone for the traceablity of the network measurements.

From 2007, the audit round will include new UKAS accredited tests to met forthcoming European standards. These include the start of a rolling programme of sample system testing. This is in response to a study carried out by the European Joint Research Centre that indicated the possibility of large concentration loses in sampling systems.

We are also seeking to reduce measurement uncertainty by improved testing of on-site calibration gases which will, in turn, lead to improvements in the routine calibration tests carried out by local site operators. During 2006 we trailed new audit procedures to meet the ratification challenges posed by the new FDMS TEOM. These tests will be further refined during 2007 to inform a robust ratification process for these measurements.

(Photo courtesy of National Physical Laboratory)

Item date 04/12/2006