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The scanning electron microscopy fibre counting scheme (SEMS) aims to assess the proficiency of laboratories counting asbestos fibres in air using scanning electron microscopy.
Important dates
Full schedule
You can find all the dates for the dispatch of samples, deadlines for receiving results, and when reports are available in the document asbestos proficiency test schedule.
Group reports
You can get the latest SEMS group reports.
Previous reports are available on the National Archives website.
Analytes in the scheme
Asbestos and other inorganic fibres are mounted on gold-coated polycarbonate filters.
Who should participate
The Control of Asbestos Regulations require laboratories that carry out this type of analysis to be accredited by the United Kingdom Accreditation Service (UKAS) to ISO 17025. The arrangements 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.
Recommended methods
The recommended methods of analysis are the ISO 14966 (2019) and the VDI 3492 (2014).
How the scheme works
There is one sample distribution per year, with samples normally dispatched in October. Each round will comprise 4 samples representing a range of asbestos and other inorganic fibres at concentration ranges typically between 10 and 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. When they submit their 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.
Detailed guidance
Detailed guidance, including how the scheme operates and hints and tips for participants, is available in our Information book for participants.
Login to enter data
If you are a participating laboratory, you can login to enter your data.
Quality control samples
SEMS sample types, prices and how to order.
Get in touch
For more information or to make an enquiry about HSE’s testing and monitoring services get in touch on GOV.UK.
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