Distribution of Grain Dust in the Community Rice Mills and Its Effects on Work Stations and Habitats
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The aim of this work was to study the distribution of total dust and respirable dust in the community rice mills and its effects on work stations and habitats. The sampling area was Ban Sao- Lao Na Suang, Det Udom, Ubon Ratchathani near to Ubon Ratchathani University. NIOSH Method No.500, 600 were used for sampling and analysis of contaminants in workplace air and measuring the mass concentration of total dust and respirable dust. The working factors could be illustrated as follow: the average working time was 5.5 hours/day, average amount of unmilled rice was 307.5 kg/day. Environmental factors including wind speed and relative humidity were measured. The average wind speed was 7.55 m/s and 45.5 %Rh. The suspended dust spread out from the mill and was carried on the wind away from the site at a distance greater than 6 m. Average concentration of total dust in the air was 2.77 mg/m3 and respirable dust was 0.73 mg/m3. The Pearson product-moment correlation coefficient was used to measure of the strength of a linear association between the environmental factors and concentration of suspended dust in the rice mills, results showed that there was no association between the relative humidity and the concentration of total dust or respirable dust. Also it showed no association between the wind speed and the concentration of total dust. However, there was association between the wind speed and the concentration of respirable dust. Additionally, the concentration of suspended dust in the rice mills was not greater than the concentration of indoor particulate matter standard which is 15 mg/m3 and 5 mg/m3 for total dust and respirable dust, respectively. However, we suggest that workers should wear cotton masks at work stations and reside at least 6 meters from work stations when not at work.