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Scanning Electron Microscopy Fibre Counting Scheme

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SEMS QC Samples Available Upon Request - Subject to Availability

Please contact the PT Team for further information

* * * *


Samples Will Be Despatched September 2024

Results Deadline will be October 2024

Proficiency Testing Scheme Overview

Our SEM Fibre Counting Scheme (SEMS) aims to assess the proficiency of laboratories counting asbestos fibres in air using Scanning Electron Microscopy. The SEM scheme is operated by HSE Testing and monitoring in association with APC, Germany and TNO, Netherlands. HSE Testing and monitoring oversees the management, registration, and membership matters together with distribution of the samples and processing the laboratory data.

Analytes in the Scheme

Asbestos and other inorganic fibres are mounted on gold coated polycarbonate filters.

Who Should Participate?

The UK Control of Asbestos Regulations require laboratories that undertake this type of analysis be accredited by the United Kingdom Accreditation Service (UKAS) to ISO 17025. The arrangments in other countries may be different. Any laboratory that is accredited to the ISO 17025 standard for this type of analysis is likely to be required to participate in an appropriate PT Scheme by their national accreditation body.

What are the Recommended Methods?

The recommended methods of analysis are the ISO 14966 (2019) and the VDI 3492 (2014).

The participant handbook provides a comprehensive overview of the operation of the SEM PT scheme and can be found under 'Useful Links'.

Operation of the Scheme

There is one sample distribution per year, with samples normally dispatched in October. Each Round will comprise four samples representing a range of asbestos and other inorganic fibres at concentration ranges typically between 10-150 fibres per mm2. The samples are intended to be analysed once only and may be retained by the laboratory after the analysis has been completed. Participants will normally have approximately 25 working days to analyse the samples and report the results. Upon submission of results participants receive a Group Summary Report. Initially participating laboratories will be given feedback on their performance but will not be formally scored. Performance criteria and a final classification will be produced as the scheme develops.

  • Samples are distributed by an approved hazardous materials carrier.
  • The Group Summary Report will be sent within one month of completion of each round.

Contact details

The Proficiency Testing Team

The HSE Science and Research Centre

Harpur Hill



SK17 9JN


Tel: +44 (0) 203 028 3382

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