Comparison of the contributions of polychlorinated dibenzo-p-dioxins and dibenzofurans and other unintentionally produced persistent organic pollutants to the total toxic equivalents in air of steel plant areas

• Level of dioxin and dioxin-like compounds in air of steel plant areas was studied.
• Relative contribution of dioxins and dioxin-like compounds was compared.
• Profiles of dioxins and dioxin-like compounds in the ambient air were stated.

The concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and the “dioxin-like” (dl) compounds polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polybrominated dibenzo-p-dioxins (PBDDs), and dibenzofurans (PBDFs), were determined in the air samples collected from six steel plants. The toxic equivalent (TEQ) concentrations of the PCDDs, PCDFs, dl-PCBs, dl-PCNs, PBDDs, and PBDFs in the air were 0.01–0.19 pg WHO-TEQ N m−3, 0.01–0.69 pg WHO-TEQ N m−3, 0.001–0.089 pg WHO-TEQ N m−3, 0.002–0.011 pg TEQ N m−3, 0.004–0.02 pg TEQ N m−3, and 0.02–0.12 pg TEQ N m−3, respectively. The PCNs were the most abundant compounds (by mass concentration), contributing about 87% of the total mass concentrations of the analytes that were found in the air of the steel plant areas. The PCDFs contributed about 47% of the total TEQs, following by the PBDFs (28%) and the PCDDs (18%). The dioxin-like compounds together contributed up to 40% of the total TEQs, so their contributions to the toxic effects that could be caused by exposure to the air of the steel plant areas were significant. The congener profiles in the air were similar to the congener profiles that were found in stack gas emissions, indicating that the steelmaking plants were possible sources of the PCDDs, PCDFs, and dioxin-like compounds that were found in the air of the steel plant areas.