INTERLABORATORY COMPARISON OF PM10 AND BLACK SMOKE MEASUREMENTS IN THE PEACE STUDY

This paper presents the results of a comparison of ambient particle me asurements conducted by 14 European laboratories in the framework of a multi-center epidemiologic study of Pollution Effects on Asthmatic Ch ildren in Europe (PEACE). Measurement of the concentration of particle s less than 10 mu m (PM10) and black smoke in ambient air was an impor tant component of the PEACE study. The Harvard impactor was used by mo st laboratories for PM 10 sampling, but Hivol samplers, beta gauge and dichotomous samplers were also used. A field study comparing these sa mplers with the Harvard impactor was conducted at five study sites. Sy stematic differences between PM10 measured with local samplers and a H arvard Impactor were between -13 and +18%. A high correlation between PM10 from the local sampler and the Harvard Impactor was found for fou r of the five centers. A field comparison of two identical black smoke samplers using either a membrane filter or the standard Whatman 1 pap er filter showed an almost threefold difference in BS concentration. T his illustrates the importance of using the standard filter. A similar comparison between two different filter papers showed only small diff erences in BS concentrations. Considerable differences were found in a n interlaboratory comparison between two centers and the other centers in reflectance measurements of exposed filters. This difference could largely be attributed to the use of different blanks in setting the r eflectometer to 100 before performing the measurements. Systematic dif ferences in weighing Teflon test filters were present between the labo ratories. Since these differences were similar for exposed and blank f ilters for 12 of the 13 centers, only small differences in PM10 concen tration (< 5 mu g m(-3)) were expected due to differences in weighing. (C) 1997 Elsevier Science Ltd.