ToolsAsbestosAir Sampling

LOD/LOQ Calculator

Calculate the Limit of Detection and Limit of Quantification for PCM fibre counting based on your sampling and analysis parameters.

Last updated 3 March 2026

About this tool

Calculate the Limit of Detection (LOD) and Limit of Quantification (LOQ) for your phase contrast microscopy (PCM) air sampling setup. These values tell you the lowest fibre concentration your method can reliably detect and quantify, based on the volume of air sampled and microscope counting parameters.

How to use

Enter the number of graticule areas you will count, the volume of air sampled in litres, and your filter and graticule dimensions (defaults are provided for standard equipment). The tool shows whether your setup achieves adequate sensitivity for clearance testing or control limit monitoring.

Reference

HSG248 — Asbestos: The analysts' guide for sampling, analysis and clearance procedures (HSE, 2021). LOD is calculated as the concentration corresponding to one fibre counted. LOQ is defined as 3.3 times the LOD, following standard analytical chemistry convention.

Revision history

3 March 2026: Initial release.

Disclaimer

This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.

Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.

All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.

By using this tool, you accept full responsibility for how you interpret and apply the information provided.

Spotted an error? Let us know.

Graticule areas counted

200 recommended, 100 minimum.

Volume of air sampled (litres)