Coal ash from power plants is divided into fly ash and bottom ash, which are produced after burning bituminous anthracite coal at 1,600°C. Coal ash is composed of fly ash (82%) and bottom ash (18%); while most fly ash is recycled as ready-mix concrete admixture and cement additive, bottom ash is left unused in landfill sites located within power plant grounds. This has been studied less comprehensively than fly ash; therefore, our aim was to assess the recyclability of the bottom ash generated by two (A & B) thermal power plants and thus identify the characteristics of hazardous substances in coal ash that are generated in power plants and evaluate the environmental contamination likelihood in the recycling of the produced coal ash. Currently, emitters such as thermal power plants have various requirements for the recycling of coal ash (bottom ash and they are also required by law to consider how the country’s environmental impact may be affected by recycling large amounts of coal ash. The concentrations of hazardous substances contained in coal ash (bottom ash) are generally lower than the criteria for soil contaminants and the standard for hazardous substances contained in designated waste. We found no significant leaching of heavy metal and its concentration; however, the levels of heavy metals in coal ash were generally low. The results of column leaching testing for potential environmental impact assessment indicated that increased leaching time might lead to the reduced ionic concentration of coal ash.

Koreans have sedentary lifestyles and use under-floor heating called Ondol as home heating systems. Sick Building Syndrome (SBS) caused by VOCs released from flooring material has been of significant interest in residential apartments. In this study, we measured exposure to VOCs by having test subjects breathe under conditions of high surface temperature. The results showed that the emission level of VOCs was high at 40oC in the early stage of the experiment. However, 20 days after the experiment began, the emission level was reduced by 0.9-4 times in each product at 40oC. The exposure to VOCs released from floor coverings was measured by taking into account the average respiratory rate, weight, and activity hour of test subjects and presuming that people are exposed to VOCs all the time while staying indoors. The level of emission from FJR of low-cost PVC floor coverings was the highest among the tested coverings, but the exposure to VOCs emission from the covering was relatively low at 0.025 mg/kg/day at 40oC. The amount of toluene detected from this experiment was the highest among VOCs emitted from floor coverings. The hazard quotient (HQ) of toluene detected in this test was over 20 times smaller than the risk characterization level of 0.1. It was, therefore, estimated that the emission of toluene from the floor surface would not be critically harmful to residents.