A survey was conducted to 890 radiological technologists working at 44 general hospitals of 16 cities and provinces across the county to determine their stress level according to regions divided into the capital city, metropolitan areas and small- and medium-sized cities. For this purpose, such factors as their working environment, role playing, job conflict and job burden were compared and analyzed according to the regions. The findings may be summed up as follows: 1. In terms of working environment, radiological technologists in the capital city were found to have the least stress(23.46), followed by those in metropolitan areas(24.53) and small- and medium-sized cities(24.85). There was a significant difference according to the regions as for the item 'worry about influence of radioactive contamination(genetic, decisive and plausible)(P<0.001). 2. As for role playing, radiological technologists in small-and medium-sized cities appeared to receive the highest stress(18.25) followed by metropolitan areas(17.71) and the capital city(16.69). There was a statistically significant difference(p<0.001) according to the regions 3. Regarding job conflict, those who work in small- and medium-sized cities turned out to get the highest stress(15.66) compared to those in metropolitan areas(15.35) and the capital city(14.44). In terms of job autonomy, there was no significant result from the survey in spite of the difference between metropolitan areas(14.87), small- and medium-sized cities(14.79) and the capital city(14.66). 4. Little difference was detected according to the regions as far as the job burden(excessive or too little) was concerned. But their was a significant regional difference in terms of patient-related factors with the capital city(11.50), small- and medium-sized cities(10.75), and metropolitan areas(10.63)(p<0.001).

Indoor air quality is affected by source strength of pollutants, ventilation rate, decay rate, outdoor level, and so on. Although technologies measuring these factors exist directly, direct measurements of all factors are not always practical in most field studies. The purpose of this study was to develop an alternative method to estimate these factors by application of multiple measurements. For the total duration of 30 days, daily indoor and outdoor NO2 concentrations were measured in 30 houses in Brisbane, Australia, and for 21 days in 40 houses in Seoul, Korea, respectively. Using a box model by mass balance and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor (emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the ventilation and source strength were estimated. In Brisbane, the penetration factors were 0.59±0.14 and they were unaffected by the presence of a gas range. During sampling period, geometric mean of natural ventilation was estimated to be 1.10±1.51 ACH, assuming a residential NO2 decay rate of 0.8 hr-1 in Brisbane. In Seoul, natural ventilation was 1.15±1.73 ACH with residential NO2 decay rate of 0.94 hr-1. Source strength of NO2 in the houses with gas range (12.7±9.8 ppb/hr) were significantly higher than those in houses with an electric range (2.8±2.6 ppb/hr) in Brisbane. In Seoul, source strength in the houses with gas range were 16.8±8.2 ppb/hr. Conclusively, indoor air quality using box model by mass balance was effectively characterized.

Volatile organic compounds (VOCs) are present in essentially all natural and synthetic materials from petrol to flowers. In this study, indoor and outdoor VOCs concentrations of houses, offices and internet-cafes were measured and compared simultaneously with personal exposures of each 50 participants in Asan and Seoul, respectively. Also, factors that influence personal VOCs exposure were statistically analyzed using questionnaires in relation to house characteristics, time activities, and health effects. All VOCs concentrations were measured by OVM passive samplers (3M) and analyzed with GC/MS. Target pollutants among VOCs were Toluene, o-Xylene, m/p-Xylene, Ethylbenzene, MIBK, n-Octane, Styrene, Trichloroethylene, and 1,2-Dichlorobenzene. Indoor and outdoor VOCs concentrations measured in Seoul were significantly higher than those in Asan except Ethylbenzene. Residential indoor/outdoor (I/O) ratios for all target compounds ranged from 0.94 to 1.51 and I/O ratios of Asan were a little higher than those of Seoul. Relationship between personal VOCs exposure, and indoor and outdoor VOCs concentrations suggested that time-activity pattern could affect the high exposure to air pollutant. Factors that influence indoor VOCs level and personal exposure with regard to house characteristics in houses were building age, inside smoking and house type. In addition insecticide and cosmetics interestingly affected the VOCs personal exposure. Higher exposure to VOCs might be caused to be exciting increase and memory reduction, considering the relationship between measured VOCs concentrations and questionnaire (p<0.05).

Indoor and outdoor nitrogen dioxide (NO2) concentrations were measured and compared with measurements of personal exposures of 95 persons in Seoul, Korea and 57 persons in Brisbane, Australia, respectively. Time activity diary was used to determine the impact on NO2 exposure assessment and microenvironmental model to estimate the personal NO2 exposure. Most people both Seoul and Brisbane spent their times more than 90% of indoor and more than 50% in home, respectively. Personal NO2 exposures were significantly associated with indoor NO2 levels with Pearson coefficient of 0.70 (p<0.01) and outdoor NO2 levels with Pearson coefficient of 0.66 (p<0.01) in Seoul and of 0.51 (p<0.01) and of 0.33 (p<0.05) in Brisbane, respectively. Using microenvironmental model by time weighted average model, personal NO2 exposures were estimated with NO2 measurements in indoor home, indoor office and outdoor home. Estimated NO2 measurements were significantly correlated with measured personal exposures (r = 0.69, p<0.001) in Seoul and in Brisbane (r = 0.66, p<0.001), respectively. Difference between measured and estimated NO2 exposures by multiple regression analysis was explained that NO2 levels in near workplace and other outdoors in Seoul (p = 0.023), and in transportation in Brisbane (p = 0.019) affected the personal NO2 exposures.

The personal exposures of nitrogen dioxide(NO2), microenvironmental levels and daily time activity patterns on Seoul subway station workers were measured from February 10 to March 12, 1999. Personal NO2 exposure for 24 hours were 29.40±9.75 ppb. NO2 level of occupational environment were 27.87±7.15 ppb in office, 33.60±8.64 ppb in platform and 50.13±13.04 ppb in outdoor. Personal exposure time of subway station workers was constituted as survey results with 7.94±3.00 hours in office, 2.82±1.63 hours in platform and 1 hours in outdoor. With above results, personal NO2 exposure distributions on subway station workers in Seoul were estimated with Monte Carlo simulation which uses statistical probabilistic theory on various exposure scenario testing. Some of distributions which did not have any formal patterns were assumed as custom distribution type. Estimated personal occupational NO2 exposure using time weighted average (TWA) model was 31.29±5.57 ppb, which were under Annual Ambient Standard (50 ppb) of Korea. Though arithmetic means of measured personal NO2 exposure was lower than that of occupational NO2 exposure estimated by TWA model, considering probability distribution type simulated, probability distribution of measured personal NO2 exposures for 24 hours was over ambient standard with 3.23%, which was higher than those of occupational exposure (0.02%). Further research is needed for reducing these 24 hour NO2 personal excess exposures besides occupational exposure on subway station workers in Seoul.

This study was carried out to evaluate the characteristics of dissolved organics based on their origins, which were divided into two categories. The first group consisted of river, lake and secondary sewage treatment effluent, which were chosen as representative of their origins. The second group were artificial samples which were made of AHA(Aldrich humic acids) and WHA(Wako humic acids). Physicochemical characteristics, biological degradability and THMFP(trihalomethane formation potential) of the samples were analysed based on the AMWD(apparent molecular weight distribution). Large portion of dissolved organic carbon(DOC) in the river and lake samples was comprised of LMW(low molecular weight), while that of AHA and WHA was HMW(high molecular weight). The DOC of the lake was evenly distributed in the all range of molecular weight. The river, lake and secondary treated effluent have lower ultraviolet(UV) absorbance at 254nm, and have a higher amount of humic acids. Higher absorbance of humic acids means that aliphatic bond and benzenoid type components that absorb UV light were contained in these kind of humic acids. It was expected that lake sample was the most biodegradable in the different samples investigated, and in order of secondary sewage treatment effluent, river, WHA and AHA based on the result of determination of specific ultraviolet absorbance(SUVA). Biodegradability showed similar result except for ABA, while dissolved organics in the range of LMW decreased during the biodegradability test, and on the contrary those of HMW increased. Production of the SMPs(soluble microbial products) was observed during humicification of dissolved organics and the SMPs were in the range of 0.7∼5.5% of DOC which was the lowest value. Sample had a higher portion of HMW showed a higher production of the SMPs. THM formation was high in the samples containing HMW and similar tendency was shown in the THMFP(trihalomethane formation potential), except for WHA.