QA QC Framework
As part of their provision of support to Local Authorities for air quality management, Defra and the Devolved Administrations provide a set of centralised QA/QC services, to assist Local Authorities using diffusive samplers for monitoring of ambient nitrogen dioxide (NO2) concentration, as part of their Local Air Quality Management process.
This is aimed at the analytical laboratories that supply and analyse the diffusion tubes, and currently comprises:
- Promotion of the independent Workplace Analysis Scheme for Proficiency (WASP), operated by the Health and Safety Laboratory, with yearly assessment against agreed performance criteria.
- Operation of a field intercomparison exercise, in which diffusion tubes are co-located with an automatic analyser: from January 2006 this is at a roadside site.
- Provision of quality control standard solutions, free of charge to laboratories that prepare and analyse NO2 diffusion tubes used by Local Authorities for LAQM purposes.
Quarterly summaries of participating laboratories' performance in the WASP scheme over the preceding 12 months, prepared by HSL/BV/NPL, are available by clicking on the links below:
- WASP Rounds 97 - 100 (Apr 2007 - Apr 2008) (PDF 132 KB)
- WASP Rounds 98 - 102 (Jul 2007 - Jul 2008) (PDF 121 KB)
- WASP Rounds 99 - 103 (Oct 2007 - Oct 2008) (PDF 119 KB)
- WASP Rounds 100 - 104 (Jan 2008 - Jan 2009) (PDF 121 KB)
- WASP Rounds 101 - 105 (Apr 2008 - Apr 2009) (PDF 137 KB)
- WASP Rounds 102 - 106 (Jul 2008 - Jul 2009) (PDF 137 KB)
- WASP Rounds 103 - 107 (Oct 2008 - Oct 2009) (PDF 121 KB)
- WASP Rounds 104 - 108 (Jan 2009 - Jan 2010) (PDF 119 KB)
- WASP Rounds 105 - 109 (April 2009 - April 2010) (PDF 118 KB)
- WASP Rounds 105 - 113 (April 2009 - June 2011) (PDF 46 KB) [Includes new Z-Score performance]
- WASP Rounds 108 - 115 (Jan 2010 - Dec 2011) (PDF 43KB) [Includes new Z-Score performance]
Investigation of the Effects of Harmonising Diffusion Tube Methodology
The report (downloadable here) investigates whether harmonisation of preparation and analsyis methods for NO2 diffusion tubes has reduced inter-laboratory variation in performance of NO2 diffusion tubes in the UK.
The following report covers an investigation into the effects of harmonising the NO2 diffusion tube methodology by the previous contractor up to 2010. It refers to a rolling performance indicator (RPI) criterion in the discussion of the WASP data. Following a consultation with the participating laboratories HSL has decided to return to the z-scoring system in the future (2011 onwards), and this time will include the percentage of results submitted, which are determined to be satisfactory, based upon a z-score of < ± 2.