|
KMID : 0895420090190040381
|
|
Journal of Korean Society of Occupational and Enviromental Hygiene
2009 Volume.19 No. 4 p.381 ~ p.389
|
|
|
Exposure Assessment of Hazardous gases in Confined Spaces
|
|
Park Hyun-Hee
Yoo Kye-Mook
Ham Seung-Hon
Chung Kwang-Jae
Jang Kyung-Jo
Yoon Chung-Sik
|
|
|
Abstract
|
|
|
|
Confined spaces are inherently dangerous workplace and many fatal and nonfatal accidents have been reported. In Korea, total 237 occupational accidents have been reported during 1999-2007. Out of 237 cases, 76 %(179 cases) was classified as fatal. Even though these accidents occur in various kinds of confined spaces, there has rarely been reported on the health hazard agent, i.e., the types of gases and their concentration ranges. Therefore in this study, we evaluated several toxic and asphyxiating gas concentrations in various confined spaces. We surveyed 57 manholes, 3 sewage treatment plants, 2 yellow radish manufacturing companies and 7 barges to measure the concentrations of oxygen(O2), hydrogen sulfide(H2S), carbon monoxide(CO), ammonia(NH3). Lower Explosion Limits(LEL) and Volatile Organic Compounds(VOCs). Those four types of confined spaces occupies 56% of accidents during last 9 years in Korea. In 57 manholes, the concentration varied according to the types of manholes; rainfall and sewage, and by location; residential and industrial areas. Sewage manhole in industrial area was evaluated as the most hazardous than other types of manhole like rainfall manholes, residential sewage manholes. The highest H2S concentration and the lowest O2 concentration at sewage manhole in industrial area were 300 ppm, 8.7% respectively. In 3 sewage treatment plants, H2S and NH3 concentrations were reached up to the 500 ppm and 200 ppm respectively. Two yellow radish manufacturing companies showed the concentrations of 316 ppm, 505.2 ppm, 90 ppm and 15.7% for H2S, CO, VOCs and O2, respectively. Seven barges showed 15.9%~20.9% oxygen concentration. Gas species and concentration ranges varied by the types and location of confined spaces; CO, H2S, O2 could be hazardous in manhole, especially manhole connected to sewage plants. CO, H2S, LEL, O2, NH3 should be controlled in sludge silo and sluge pumping confined spaces in sewage treatment plant. The activity of lifting out radish from the storage tank was evaluated more hazardous rather than the other activities in yellow radish manufacturing industry. The employers must conduct the survey to identify all possible confined spaces in their local workplace prior to performing the tasks. At the national level to reduce the accidents in the confined spaces, we suggest that systemic approach and active education program including possible hazards, standard operation procedures, ventilation plan, and personal protective equipment in confined spaces should be implemented.
|
|
|
KEYWORD
|
|
|
confined space, oxygen deficiency, hydrogen sulfide, manhole
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|