LAUSR

On of the problems in the UK is that conventional sampling for asbestos for analysis by optical microscopy is of limited sensitivity. For example, for 480 litre samples and 200 fields counted on 25 mm diameter filters a count of 20 fibres give a Limit of Quantification of 0.01 fibres/ml: 10,000 fibres/m3. Given than an annual exposure of such concentration of amosite would generate a mesothelioma risk of about 450 per million for a new-born child with a life expectancy to age 100. To limit the risk of such child to the “acceptable” level of 1/million/year it is necessary to be able to quantify amosite concentrations of less than 2 fibres/m3. Using a combination of increased flow rates through reduced area filters, e.g. reducing the effective diameter of the filter to, say, 6 mm, counting more than 200 fields and adopting modified sample preparation, it has been found feasible to reduce the LoQ to 100 fibres/m3. It is anticipated that by adopting TEM with EDXA should further reduce the LoQ to about 10 asbestos fibres/m3. Assessment of improved analysis techniques are currently (March 2020) in hand.