Not AvailableMagnitude of dust concentration in breathing zone in manual harvesting, and threshing operation of wheat crop were measured. The dust levels were 11.89, 4.67 and 3.20 mg/m3 for in-halable, thoracic and respirable dusts respectively. Dust concentration was highest in breathing zone of the workers feeding the crop into thresher as compared to the workers engaged in harvesting with sickle, workers supplying crop to feeder and workers collecting threshed grains. The analysis of particle size distribution of dust indicated relatively low mass proportion of particles smaller than 2.5 μm and high percentage of particles over 7 μm diameters. Three types of dust filters, i.e. cloth, foam and non-woven fabric were selected and evaluated for filtration efficiency and pressure drop. An experimental setup was developed to measure filtration efficiency and pressure drop with varying filter area and dust concentration. The filtration efficiency of dust filters ranged from 50.76 to 59.71% (cloth), 89.19 to 92.78 % (foam) and 96.50 to 98.70 % (non-woven fabric) and pressure drop ranged from 5 to 17.83 (cloth), 23.83 to 38.50 (foam) and 14.17 to 27.67 (non-woven fabric) mm of H2O for three different filter areas and dust concentrations, respectively. The results of subjective evaluation of dust protectors with field workers showed that, non-woven fabric was most preferred because of higher filtration efficiency and lower pressure drop. It was concluded that, non-woven fabric based dust protector provides the highest dust protection with lowest breathing resistance.Not Availabl
