. Dust measurements were made in 51 iron, 9 steel, and 8 nonferrous foundries, at which 4,316 foundrymen were working. The sampling lasted at least two entire shifts or work days continuously during various operations in each foundry. The dust samples were collected at fixed sites or in the breathing zones of the workers. The mass concentration was determined by weighing and the respirable dust fraction was separated by liquid sedimentation. The free silica content was determined by X-ray diffraction. In the study a total of 3,188 samples were collected in the foundries and 6,505 determinations were made in the laboratory. The results indicated a definite difference in the dust exposure during various operations. The highest dust exposures were found during furnace, cupola, and pouring ladle repair. During cleaning work, sand mixing, and shake-out operations excessive silica dust concentrartions were also measured. The lowest dust concentrations were measured during melting and pouring operations. Moderate dust concentrations were measured during coremaking and molding operations.The results obtained during the same operations of iron and steel foundries were similar. The distribution of the workers into various exposure categories, the content of respirable dust and quartz, the correlation between respirable dust and total dust, and the correlation between respirable silica and total dust concentrations are discussed. Observations concerning dust suppression and control methods are briefly considered. f.oundries indicate that, in spite of efforts toward dust control, respirable silka dust still remains an outstanding hea,lth hazard in the foundry industry in many countries (2,5,6,7,8,12,14,19,22). The different parameters of the dust measured and the variety of instruments and techniques employed usualJ.ly prevent valid international comparisons of dust levels~n foundries.So far data on the dust situaHon in Finnish noundries have been insufficient. However, results of dust measurements from a limited group of foundries have been reported previously (16). Resul'ts of the study indicated that in many operations the work,ers in thesefactollies were exposed to high silica dust concentrations.The present paper reports a comprehensiVle systematic dust survey which was 19 made during 1972-1974 in most Finnish iron and steel founddes 'Operating at the time. Dust measur,ements were also made in a selected group of nonferrous anoy foundries in which molding sand was used.In our study we particularly emphasized the evaluation of dust exposure in various work operations and in different occupahans in foundri'es. Dust evaluations included the determina,tion of the total mass ooncentration, the respir,able fraction of dust, and the composition of the dust. Observations were also made of pertinent factors such as dust suppression and control methods, ventilation, and work methods. The results and detailed discussions concerning the methods have been partly reported elsewhere (10,20). MATERIALS AND METHODSThe foundries studied...

Precision and accuracy of foundry dust exposure estimates from air sampling data. Scand. j. work environ. & health 2 (1976) 13-18. Errors in the sampling methods and in the determination of respirable size quartz in foundry dust have been evaluated and discussed. In general, the total precision of dust sampling and analysis was better than 20 0/0. The term "exposure dose" is introduced and defined. The temporal variation associated with measuring exposure dose is assessed with reference to the use of a log-normal distribution of air sampling results. The logarithmic standard deviations of dust concentrations at fixed sites and jobs are calculated.

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