<abstract xmlns="http://www.w3.org/1999/xhtml"> Background: Asphyxiation is the most dangerous hazard in confined spaces. In Thailand, several large rice mills have underground pits in order to transport moist paddy to baking machines. Prolonged unbaked paddy piles can produce several gases that can displace oxygen inside the pits.Objective: This study describes concentrations of hazardous gases and oxygen content inside the underground pits of rice mills in Thailand.Methods: At six randomly selected large rice mills in this study, fresh paddy piles were divided into four groups, based on moisture content (&lt;14%, 15-20%, 21-30%, and >30% wet basis (w.b.)). Gas measurement was conducted with direct reading instruments including infrared spectrophotometer (Miran 1BX for CO2, N2O) and toxic gas detector (QRAE plus for CO, NO2, % O2 and flammable gas) at three different depth levels (top, middle, bottom) inside the pits.Results: The concentrations of CO2, CO, N2O, NO2, and % O2 were in the ranges of 1.7-5438 ppm, 0-61 ppm, 0-4.9 ppm, 0-0.8 ppm, and 19.9-21.6%, respectively whereas concentrations of flammable gas (% lower explosive limit; [%LEL]) were not detected. The highest concentrations of gases were at the middle depth pit level, inside the paddy piles with the highest moisture contents (>30% w.b.). The detected concentrations of gases were higher than limit values based on time-weighted average but below limits immediately dangerous to life.Conclusion: Although oxygen-deficient atmosphere was not detected under the working conditions of the survey. The findings demonstrated that concentrations of hazardous gases were dependent on both storage time and the moisture content of paddy piles. Measures should be developed to ensure that entry into these pits strictly complies with safety laws</abstract>

Background: Asphyxiation is the most dangerous hazard in confined spaces. In Thailand, several large rice mills have underground pits in order to transport moist paddy to baking machines. Prolonged unbaked paddy piles can produce several gases that can displace oxygen inside the pits.Objective: This study describes concentrations of hazardous gases and oxygen content inside the underground pits of rice mills in Thailand.Methods: At six randomly selected large rice mills in this study, fresh paddy piles were divided into four groups, based on moisture content (<14%, 15-20%, 21-30%, and >30% wet basis (w.b.)). Gas measurement was conducted with direct reading instruments including infrared spectrophotometer (Miran 1BX for CO2, N2O) and toxic gas detector (QRAE plus for CO, NO2, % O2 and flammable gas) at three different depth levels (top, middle, bottom) inside the pits.Results: The concentrations of CO2, CO, N2O, NO2, and % O2 were in the ranges of 1.7-5438 ppm, 0-61 ppm, 0-4.9 ppm, 0-0.8 ppm, and 19.9-21.6%, respectively whereas concentrations of flammable gas (% lower explosive limit; [%LEL]) were not detected. The highest concentrations of gases were at the middle depth pit level, inside the paddy piles with the highest moisture contents (>30% w.b.). The detected concentrations of gases were higher than limit values based on time-weighted average but below limits immediately dangerous to life.Conclusion: Although oxygen-deficient atmosphere was not detected under the working conditions of the survey. The findings demonstrated that concentrations of hazardous gases were dependent on both storage time and the moisture content of paddy piles. Measures should be developed to ensure that entry into these pits strictly complies with safety laws

Original article. Hazardous atmosphere in the underground pits of rice mills in Thailand

Department of Industrial Hygiene and Safety, Faculty of Public Health, Burapha University, Chonburi 20131,

Department of Community Medicine, Faculty of Medicine, Faculty of Technology, Khon Kaen University, Khon Kaen 40002,

Department of Epidemiology, Faculty of Public Health, Khon Kaen University, Khon Kaen 40002,

Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen 40002,

Asian Biomedicine

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Background: Asphyxiation is the most dangerous hazard in confined spaces. In Thailand, several large rice mills have underground pits in order to transport moist paddy to baking machines. Prolonged unbaked paddy piles can produce several gases that can displace oxygen inside the pits.Objective: This study describes concentrations of hazardous gases and oxygen content inside the underground pits of rice mills in Thailand.Methods: At six randomly selected large rice mills in this study, fresh paddy piles were divided into four groups, based on moisture content (30% wet basis (w.b.)). Gas measurement was conducted with direct reading instruments including infrared spectrophotometer (Miran 1BX for CO2, N2O) and toxic gas detector (QRAE plus for CO, NO2, % O2 and flammable gas) at three different depth levels (top, middle, bottom) inside the pits.Results: The concentrations of CO2, CO, N2O, NO2, and % O2 were in the ranges of 1.7-5438 ppm, 0-61 ppm, 0-4.9 ppm, 0-0.8 ppm, and 19.9-21.6%, respectively whereas concentrations of flammable gas (% lower explosive limit; [%LEL]) were not detected. The highest concentrations of gases were at the middle depth pit level, inside the paddy piles with the highest moisture contents (>30% w.b.). The detected concentrations of gases were higher than limit values based on time-weighted average but below limits immediately dangerous to life.Conclusion: Although oxygen-deficient atmosphere was not detected under the working conditions of the survey. The findings demonstrated that concentrations of hazardous gases were dependent on both storage time and the moisture content of paddy piles. Measures should be developed to ensure that entry into these pits strictly complies with safety laws

Background: Asphyxiation is the most dangerous hazard in confined spaces. In Thailand, several large rice mills have underground pits in order to transport...

Original article. Hazardous atmosphere in the underground pits of rice mills in Thailand

Published Online: Feb 04, 2017

Page range: 867 - 874

DOI: https://doi.org/10.5372/1905-7415.0606.133

Keywords
Confined space, hazardous atmosphere, hazardous gases, paddy, rice mill

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Original article. Hazardous atmosphere in the underground pits of rice mills in Thailand

Published Online: Feb 04, 2017

Page range: 867 - 874

DOI: https://doi.org/10.5372/1905-7415.0606.133

KeywordsConfined space, hazardous atmosphere, hazardous gases, paddy, rice mill

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
Confined space, hazardous atmosphere, hazardous gases, paddy, rice mill