Measurement of airborne fibre concentration in the air - Comparative studyof the membrane filter method and direct reading instruments for counting airborne fibres - Preliminary results

The use a direct reading instruments for counting airborne fibres is increa singly widespread. Two such instruments (the FM-7400 and the Fibrecheck FC- 2) were compared to the conventional method of filter sampling and phase co ntrast optical microscopy counting. It emerged that direct reading instrume nts are rapid and easy to use. However if used as is, they can produce tota lly flawed results when measuring certain granulometric classes of fibrous aerosols. It is therefore important to check their suitability for fibre de tection when seeking to measure fibre concentrations in the air. If they ar e to give results which go beyond mere assessment, they must be calibrated with reference to the conventional method.