Myung-Hee Kwon

Formation and emission status of PCDDs/PCDFs in municipal solid waste incinerators in Korea

This study was carried out to examine the formation and the emission status of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) in the flue gases of commercial-scale municipal solid waste (MSW) incinerators, and thus to provide the engineering data for the reduction of PCDDs/PCDFs emitted from MSW incinerators. The formation concentrations of the PCDDs/PCDFs generated at the outlet of waste heat boilers (WHB) were in the range of 1.18-29.61 ng-TEQ/N m3 (average 5.75 ng-TEQ/N m3), while the emission concentrations at the stacks were in the range of 0.026-4.548 ng-TEQ/N m3 (average 0.924 ng-TEQ/N m3). Two major 2,3,7,8-substituted congeners were 2,3,4,7,8-PeCDF and 2,3,4,6,7,8-HxCDF, and their concentrations were up to 50% and 64% of total TEQ values at the outlet of WHB and the stack, respectively. From the results of multi-regression analysis, the formation concentration of PCDDs/PCDFs could be predicted as follows with the correlation factor of r2 = 0.962: PCDDs/PCDFs (ng-TEQ/N m3) = 3.036 (Cl) + 0.094 (T1) - 0.472 (Combustibles) + 0.059 (CO) - 0.039 (THC) - 3.366 (H) + 22.157, where T1 (degrees C) is the temperature at the outlet of the WHB. Cl, Combustibles and H are given as percentages and the others are in parts per million.

Estimation of health risk and effective dose based on measured radon levels in Korean homes and a qualitative assessment for residents’ radon awareness

More than 50% of the worldwide effective radiation dose from natural sources is known to be due to 222Rn. Indoor radon levels were measured in homes with long-term exposure and in relation to time spent for residents. Measurements were conducted after categorizing homes by type, and the results (mean ± S.D) showed that detached houses, apartments and multifamily houses had radon concentrations of 97 ± 110, 51 ± 24 and 59 ± 34 Bq/m3, respectively. Surveys were conducted with 620 people to analyse resident awareness of radon levels and time that residents spend in homes. Using these results, the annual effective dose and risk level were computed. The survey showed that residents of Korean homes had little awareness regarding the source of radon, exposure routes and contamination levels. The excess risk of lung cancer after exposure for 70 years was determined to be 0.55/100 people, which jumped to 2.7/100 people for residents in detached houses in highly exposed areas. Compared to the effects of radon exposure in workplaces and schools, the health risks from radon in Korean homes are especially high. Therefore, the management policies for susceptible groups are important.

Assessment of Nicotine and PM10 Concentration in Indoor Air by Smoking Activities

Indoor air qualities in smoking banned and smoking free facilities are investigated for figure out the relationship between environmental factors and concentration of smoking pollutants. The KS H ISO 18145 and indoor air quality standard method were used for analysing the nicotine and particulate matter(PM10), respectively. The highest concentration of fine particles and nicotine is recorded in billiard hall. A significant positive relationship between smoking frequency and concentration of indoor pollutants was observed. Among the environmental factors, the ventilation time and frequency was revealed as a main factor influencing on reducing the concentration of fine particles and nicotine which are emitted from indoor smoking.

Airborne Bacteria Concentration and Species Identification in Residential Living Spaces

Objectives: Exposure to airborne bacteria is associated with adverse health effects such as respiratory and infectious diseases. This study evaluated airborne bacterial concentrations in the living rooms, kitchens, and toilets of 30 homes. Methods: Bacteria were sampled with an MAS100 impactor in three spaces in the subject homes between April 2014 and February 2015. Bacteria were grown on TSA plates for 48 hours at 35C. The bacterial strains were isolated and amplified by polymerase chain reaction. Results: The most culturable bacteria were found in toilets (624.0 CFU/m, GM: 417.3 CFU/m), followed by in the kitchen (503.8 CFU/m, GM: 324.9 CFU/m). The dominant genera identified were: Staphylococcus sp.(19%), Micrococcus sp.(16%), and Bacillus sp.(11%) in the indoor air and Bacillus sp. (30%) in the outdoor air. Gram-positive bacteria comprised more than half of all colonies. Conclusion: In this study, culturable bacteria concentrations were higher than those reported in other spaces. Therefore, it is important to control relative humidity and remove moisture to prevent bacteria from multiplying. Additionally, the dominant species in indoor air were Staphylococcus sp. and Micrococcus sp. These are found on the human skin, mucous membranes, and hair, so human activity can affect bacterial distribution. Therefore, cleaning and controlling moisture are important for reducing indoor bacterial concentrations.