We investigated dissatisfaction of elements of local exhaust system, needs for local exhaust system, and information networks for local exhaust system from June 1998 to September 1999 using the questionnaire structured. It contained questions concerning general characteristics of factory and local exhaust system, troubles and dissatisfaction of elements of local exhaust system, and information networks for local exhaust system. The collected data were analyzed by descriptive statistics analysis. Information networks for local exhaust system were analyzed by multidimensional scaling using path distance of network analysis and by graph analysis using Krackplot. Among complaints of local exhaust system, that of duct has show the highest percentage of complaint. In the information network for local exhaust system, Seoul is positioned in the center of network with mediating role.

Since the regulation of MSDS (Material Safety Data Sheets) had started from July 1996, employers were required to furnish MSDS for the chemicals in use in their workplace. However, many MSDS did not contain upright information for the chemicals, and they were not updated regularly, and were not written in the standard format required by the Industrial Safety and Health Act (ISHA). The purposes of this study were 1) to examine the reliability of MSDS for mixed solvents, 2) to provide reliable MSDS to employers or employees, 3) to find out any difficulties in implementing MSDS after the initiation, and 4) to promote regular MSDS updating and to ensure the reliability of MSDS for chemical manufacturers. To check the reliability of MSDS of mixed chemicals, 21 samples of mostly degreasing solvents were collected along with their MSDS from the work place. The samples were analyzed by gas chromatography-mass selective detector(GC-MSD). Their components were classified as saturated hydrocarbon, cyclic hydrocarbon, aromatics, and halogen containing hydrocarbon, and the amount of each class were measured. Manufacture's MSDS were compared with the actual composition of the collected samples, and further examined the reliability by checking whether the chemicals analyzed were included in the MSDS correctly. Finally, each item of MSDS was evaluated whether the MSDS correspond to the regulation required by ISHA. The results were following: 1) most of the degreasing solvents in MSDS were incorrect in their composition and contents, 2) the information in the MSDS including hazard classification, exposure level, toxicity, regulatory information were incorrectly provided, and 3) some MSDS did not disclose carcinogens in their MSDS. Continuous monitoring of MSDS was required to ensure reliability of MSDS. The Chemicals containing hydrocarbons from C10-C15 need to be tested to provide toxicity data. In addition, governmental support for providing correct MSDS was recommended to ensure reliability of MSDS. The MSDS regulation relating to the confidential business information may need to be revised to ensure reliability of MSDS.

Objectives : The purpose of this study is to analyze the factors associated with respirator usage on the basis of reasoned action theory. Methods : The data were collected from August 1 to September 30 1999, and study subjects consisted of 303 workers who were employed in the manufacturing industries. A self-administered questionnaire was used to measure the attitude, subjective norm and related factors. Results : In bivariate analysis, the variables related to protector usage were prevention of occupational disease, protection of toxic material, disturbance during working, troublesome of usage, proper exchange of protector. Multivariate logit analysis was used to estimate factors associated with respirator usage. Significant predictors that are related to respirator usage were attitude toward the behavior, size of industry and proper exchange of protector. Conclusions : The results suggest that it is strongly required to focus on attitude toward the behavior in order to improve workers' usage of respirator.

The aim of this study was to evaluate the prevailing ergonomic conditions regarding low back injury in an assembly factory, In this study, analytic biomechanical model and NIOSH guidelines were applied to evaluate risk levels of low back injury for automobile assembly jobs. Total of 246 workers were analysed. There were 10 jobs with greater back compressive forces than 350kg at L5/S1. Also there were 44 jobs over Action Limit in terms of 1981 NIOSH guidelines. This could in part be explained by the ergonomic conditions of the companys analysed as not hazardous, with a relatively low duration of 'combined' extreme work posture. However, more ergonomic intervention could be done based on those results.

Coke-oven workers are regularly exposed to coke oven emissions (COE), which consist primarily of polynuclear aromatic hydrocarbons (PAH) and volatile organic components. This study assessed the exposure of coke-oven workers to COE and PAH. The results of this study are as follows. 1. Among the 136 samples on coke-oven workers 33.1% exceeded the occupational exposure limit to the Coal Tar Pitch Volatiles ($0.2mg/m^3$) established by the Korean Ministry of Labor and American Conference of Governmental Industrial Hygienists(ACGIH). 2. The coke-oven workers were classified into twelve job categories and there was statistically significant difference among the airborne concentrations of COE and PAH in twelve job categories(p<0.001). 3. There was no significant difference of the airborne concentrations of COE between NIOSH method and OSHA method applied. 4. There was a significant correlation between the airborne concentrations of total PAH and COE(r=0.733, p<0.01). 5. The percentage of naphthalene in total PAH was 55.9% and the highest among those of 16 PAHs. There was a significant correlation between the airborne concentrations of naphthalene and total PAH(r=0.90, p<0.01) and this study recommends naphthalene as the index component of PAH.

This study was performed to evaluate tannin exposure by wooddusts for workers in furniture factories and to investigate the relationship between tannin exposure and sino-nasal cancer risk. In order to explore possible cytological changes leading to nasal cancer, we have examined 50 male furniture workers and 50 matched controls using brush cytology. The results we have obtained in this study were as follows: 1. The tannin contents of woods used in woodworking factories have been measured and varied from 0.43 to 8.72 mg tannic acid equivalent per gram wood, for reconstituted softwood and turpentine (Syncarpia glomuliferia) respectively. 2. Airborne tannins in wooddusts were also determined by area and personal exposure. The values of mean exposures for both methods are ranged from 3.1 to $5.0{\mu}g/m^3$ and from 4.6 to $14.5{\mu}g/m^3$ in furniture manufactures. 3. Over nasal cytology scores 2, the scores of study group were slightly more than control group and this kind of metaplasias seemed to be occurred over $2mg/m^3$ wooddust and $6{\mu}g/m^3$ tannin exposure. Keratinising squamous metaplasia was investigated at nasal cytology score 3 and $10{\mu}g/m^3$ tannin exposure. The nasal cytology score 4 was seemed to be atypical squamous metaplasia. 4. To find out contributing factors to nasal cytology change, odds ratio that is one of fundmental biostatistics was applied. Actually the relationship between wooddust, tannin concentration and metaplasia were not meaningful, but the relationship between working experence more than 15 years and metaplasia was calculated as 1.83. This reveals that significant clinical abnormalities could be influenced from the years of woodworking experiences. However further research is required to evaluate the significance of the data, for the purposes of sino-nasal risk assessment, standard setting to prevent nasal cancer occurrences and possibility of changing workplace.

Designing the industrial ventilation system is the complex and time-consuming job. It could generate some errors in the design calculations if one uses the hand-calculator or the spreadsheet program. To overcome these difficulties, VSDS(Ventilation System Design Software) had been developed a few years ago. But, it had the difficulty in designing a complex system having many branches because the user can not see the layout of the system on the screen. Another difficulty is that VSDS had been based on the assumption of the standard air condition. VSDS has thus been improved to overcome the shortcomings of the old version of VSDS.

Controlling the over-exposure of welding fumes is not an easy problem because neither general nor local exhaust ventilation systems could be successfully applied. A jet air supplying welding mask was development to reduce the exposure level of welding fumes. The jet airs tream pushes the welding fumes away from the breathing zone by using the frictional characteristic of jet. Laboratory experiments were conducted to optimize the efficiency of controlling welding fumes. Thereafter, its performance was tested in a laboratory and an industrial field. The efficiencies of reducing the welding fume exposure were about 90% and 80% in a laboratory and an industrial field, respectively. Additionally, it resulted in elimination of heat inside the mask and enhancement of clear visuality.

Inhaled halogen compound was examined through micronucleus tests and toxicity tests using SD (Sprague-Dawley) rats with repeated dosages for six hours a day, five days a week, during four weeks. In four-week repeated exposure, no specific sign caused by the $CF_3I$ compound was observed on the clinical symptoms, body weight variation, feed consumption, and urinalysis data in the testing groups with reference to the control group. In hematological and biochemical blood tests of the testing groups, the significant, but in their normal ranges, value dependencies of glucose, aspartate aminotransferase, alanine aminotransferase and etc., on the halogen carbohydride concentration was observed. In histo-pathological tests, no specific lesion or concentration dependent change due to the $CF_3I$ compound dosage was observed in both sexes of the female and male in the tested animals. But, micronucleus tests on marrow cells extracted from the tested animals which were repeatedly exposed in the $CF_3I$ compound during four weeks, the frequencies of micronuclei were significantly increased dose-dependently compared to the control groups.

This study was performed to investigate monoacetylbenzidine(MABZ) and benzidine(BZ) hemoglobin adducts among workers who worked at benzidine based dye manufacturing company, and exposed by benzidine and benzidine based dye. The hemoglobin adducts were compared with work environment assessment result for evaluating the usefulness of biological monitoring. The mean BZ hemoglobin adducts among the first synthesis worker's hemoglobin adducts were $40.69{\mu}gBZ/g$ Hb and those of dry and packing workers were $22.14{\mu}gBZ/g$ Hb. The mean of MABZ hemoglobin adducts among 1st synthesis workers were $255.84{\mu}gMABZ/g$ Hb, dispersion worker's hemoglobin adducts were $76.17{\mu}gMABZ/g$ Hb and synthesis worker's hemoglogin adducts were $28.66{\mu}gMABZ/g$ Hb. Work environment assessment results during past 3 years were $0.0065mg/m^3$ and $0.5659mg/m^3$ of benzidine based dye concentration in ambient air of drying and packing only. Dye producing process was categorized by the possibility of exposure to benzidine and benzidine based dye. BZ and MABZ hemoglobin adducts were $19.55{\mu}gBZ/g$ Hb, $119.80{\mu}gMABZ/g$ Hb among workers who exposed by benzidine dihydrochloride and $16.32{\mu}gBZ/g$ Hb, $316.56{\mu}gMABZ/g$ Hb among workers who exposed by benzidine based dye. BZ hemoglobin adducts were not detected among control group and MABZ hemoglobin adducts were $5.33{\mu}gMABZ/g$ Hb. The differences between control and other exposed group was statistically significant. But there was no statistically significant differences between benzidine dihydrochloride exposed process and benzidine based dye exposed group. BZ and MABZ hemoglobin adducts were $2.23{\mu}gBZ/g$ Hb, $76.17{\mu}gMABZ/g$ Hb and $3.46{\mu}gBZ/g$ Hb, $21.33{\mu}gMABZ/g$ Hb. So hemoglobin adducts of MABZ were 5 ~ 30 time higher than those of BZ(P<0.003). Above results indicate that work environment assessment didn't detected benzidine and benzidine based dye in ambient air but biological monitoring detected those of hemoglobin adducts. Two group's hemoglobin adducts exposed benzidine dihydrochloride and benzidine based dye were high level but wasn't statistically significant and those were not detected in control group.

In industrial field, there are several operations where a horizontal unidirectional airflow is used to control airborne contaminants. When a worker is immersed in a uniform freestream, a recirculating airflow can be created downstream of the worker by the phenomenon of boundary layer seperation. If the contaminant source and the breathing zone are within this near-wake region, high exposure may occur. The investigation for the effect of contaminant source location on worker exposure was performed by using CFD(Computational Fluid Dynamics). The airflow field was numerically calculated by assuming a steady flow and using the standard $k-{\varepsilon}$ turbulence model. As the results were compared with experimental data, the applicability of CFD was successfully verified. Subsequently, the breathing zone concentrations of the worker were predicted and compared with experimental data. The effects of contaminant density and turbulence intensity of freestream on worker exposure were evaluated.

This study was conducted at occupational health laboratories in Seoul and Gyunggi district area from December, 1999 to January, 2000. The main purpose of this study was to survey the actual condition of safety and health by questionnaire and checklist and to assess the performance of fume hoods and the airborne exposures to chemicals in the laboratories. The chemicals in the cabinet were not classified by hazardous properties and the compressed gases were not stored safely. The prevalences of laboratories having first aid kits, fire extinguishers, and safety showers were found to be 18%, 55%, and 9%, respectively. Most laboratory workers were not educated for safety and health. Also, there was no performance evaluation for hazards and risks. The fume hoods in laboratories had not been annually inspected by checklist and the face velocity had been checked more than one time in the previous year for only 18% of them. Five percent of fume hoods had the face velocity more than 4.0 m/sec and 17% had no capture performance. Detected organic solvents were methylenechloride, acetone, ethylbenzene, isopropanol, xylene, methylisobutylketone, trichloroethylene, and toluene. The concentrations of organic solvents were much less than the occupational exposure limits proposed by the Ministry of Labor in Korea. This study showed that the actual condition of safety and health was not appropriate for laboratory workers. It is recommended that laboratory workers should be educated for the treatment and storage of hazardous chemicals and compressed gases to improve the working environment of the occupational safety and health laboratories.

This study was carried out to investigate relationship between plasma $\delta$ - aminolevulinic acid (ALAP) and lead exposure indices in exposure to lead. The subjects were 218 male workers in 2 storage battery companies and 2 secondary smelting companies. Blood lead(PbB), blood zinc-protoporphyrin( ZPP), urinary $\delta$ - aminolevulinic acid (ALAU), hemoglobin(Hb), and hematocrit(Hct) were measured as lead exposure indices. The results were as follows, 1. The means of blood lead and blood ZPP concentration of subjects were $27.2{\pm}14.0{\mu}g/d{\ell}$ and $55.1{\pm}47.6{\mu}g/d{\ell}$, respectively. The means of plasma $\delta$ - ALA and urinary $\delta$ - ALA concentration were $18.9{\pm}25.1{\mu}g/d{\ell}$ and $2.1{\pm}4.6mg/{\ell}$, respectively. 2. The concentration of ALAP was $11.2{\mu}g/{\ell}$ for below $20{\mu}g/d{\ell}$ PbB, $12.8{\mu}g/{\ell}$ for from $21-40{\mu}g/d{\ell}$ PbB, and $51.2{\mu}g/{\ell}$ for over $40{\mu}g/d{\ell}$ PbB, respectively. 3. ALAP was significantly correlated with ALAU(r=0.829, p<0.01), ZPP(r=0.724, p<0.01) and PbB(r=0.552, p<0.01).