Assessment of PCDD/F and dl-PCB levels in air before and after the start-up of an energy recovery plant in northern Spain

Waste management in the European Union relies on circular economy principles, emphasizing waste reuse and recycling. This study assess whether the implementation of an energy recovery plant (ERP) has affected air quality, and to estimate the extent of this impact. Between 2017 and 2023, concentrations of PCDD/Fs and dl-PCBs were analyzed, using 235 air samples collected from two urban-industrial areas (Impact and control) in two periods. To assess the ERP's impact on ΣPCDD/F + dl-PCB levels, the means of the monthly level's medians before and after start of operations were compared. Data were log-transformed, and the mean of the monthly level's medians of the 17 PCDD/Fs congeners and 12 dl-PCBs were compared before and after implementation using a BACI (Before-After Control-Impact) study design. As for the results, the levels of PCDD/Fs and dl-PCBs were significantly higher in impact (11.94 fg TEQ·m^-3) compared to control (5.29 fg TEQ·m^-3). Both zones exhibited a downward trend over the study period. The mean difference in ΣPCDD/Fs + dl-PCBs between zones was 1.09 fg TEQ·m^-3 in the before-period and 0.61 fg TEQ·m^-3 in the after period. However, this difference was not statistically significant. In conclusion, a progressive and significant decrease in the mean levels of PCDD/Fs + dl-PCBs was observed in both areas, with concentrations converging toward similar values by the end of the period. The impact analysis did not reveal any significant differences in the mean concentrations of ΣPCDD/Fs + dl-PCBs between areas and periods. The similarity in congener composition profile of PCDD/Fs and dl-PCBs before and after commissioning suggests that atmospheric concentrations are largely influenced by the iron and steel industries.