Classification of particles from the farm environment by automated sizing,counting and chemical characterisation with scanning electron microscopy-energy dispersive spectroscopy

About 60 000 particles in 288 aerosol samples collected during farm work ha ve been characterised with automated particle analysis using scanning elect ron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Based on EDS-analysis of materials with known composition (potato flour, alpha-qu artz, K-feldspar and B-wollastonite), criteria were developed for classific ation of particles as: ( 1) organic, (2) silicon-rich (silica), and (3) oth er inorganic particles. The reproducibility of the relative mass proportion s in dust samples collected during farm work was 0.078 when approximately 2 00 particles were characterised per sample. Field samples from the farm env ironment showed clear differences in composition. Generally, inorganic part icles dominated the particle mass. The proportion of the organic particle m ass was highest for tending of swine and poultry, 55 and 38% respectively. Silica particles amounted to 10 to 20% of the total mass during handling cr ops, e.g. grain, straw, hay, potatoes, and onions. It seems likely that the results can be used in etiologic studies, but further validation would be needed for quantitative purposes.