Proficiency Testing for Measurement of Total Mass and Elements in Workplace Air Filters. Round 11

In Round 11 of the proficiency-testing programme laboratories from England, Lithuania, Finland, Sweden, Denmark and Norway have participated. Filters and cassettes were distributed to the laboratories in October 2004. The laboratories were asked to pre-weigh the filters prior to exposure to welding fume, and return the prepared filter cassettes by 19th of November 2004. Realistic workroom air filters and synthetically produced reference filters were distributed to the participating laboratories in January 2005 with a deadline of reply by 25th of February 2005. The laboratories were asked to determine a number of occupational important elements (Ag, Cd, Cr, Fe, Mn, Ni, Pb, Zn) listed in the enclosed protocol in two filter matrices and total mass on the welding fume filters. The inter-laboratory variance for the individual elements after rejection of outliers shows acceptable agreement among participants.