Conservatism of Environmental Quality Standards for Petroleum Hydrocarbon Contamination in Urban Areas: Vapor Intrusion Risk-Based Evaluation

Abstract Environmental management of urban groundwater contamination by petroleum hydrocarbons (PHCs) necessitates a risk-based decision-making framework that integrates environmental quality standards (EQS) for comprehensive protection. We conducted a risk-based evaluation of the conservatism of EQSs in South Korea across relevant media—namely soil, groundwater, and indoor air—for sites contaminated with PHCs. Conservatism was assessed by comparing human health risks at concentrations corresponding to EQSs with risk thresholds at contaminated sites. The study site was conceptualized as an urban residential area affected by petroleum spills from adjacent underground storage tanks, with contamination levels in each medium was assumed to correspond to Korea’s EQSs. Vapor intrusion was identified as the primary pathway for hydrocarbon exposure in urban underground environments. The PVI2D model was employed to simulate indoor air concentrations of hydrocarbons, and human health risks—including excess lifetime cancer risk and hazard quotients—were estimated using U.S. EPA standard equations. Results indicates that health risks from PHCs-contaminated soil at levels corresponding to soil EQSs were substantially lower than the risk thresholds, demonstrating that the soil EQSs are more conservative than risk-based criteria. This conservatism may vary depending on site-specific conditions. Soil EQSs for total petroleum hydrocarbons (TPH) were particularly conservative, even when accounting for uncertainties in TPH composition. Groundwater EQSs were considerably more conservative than those for other media, while indoor air EQSs were comparatively less conservative. Comparative evaluation of these EQSs may facilitate multi-criteria decision-making in environmental management.