PCDD/PCDF and dl-PCB in the ambient air of a tropical Andean city: Passive and active sampling measurements near industrial and vehicular pollution sources

• PCDD/F and dl-PCB concentrations were measured at four urban locations of the densely populated Andean city of Manizales.
• Manizales has an Andean forest climate with high vehicular density and relatively low wind velocity.
• Concentrations of passive samples are more associated with industrial source areas.
• Concentrations in particle phase (PM10) are more associated with mainly vehicular source areas.
• Results obtained are the first data from passive monitoring in urban zones of Colombia.

Concentration gradients were observed in gas and particulate phases of PCDD/F originating from industrial and vehicular sources in the densely populated tropical Andean city of Manizales, using passive and active air samplers. Preliminary results suggest greater concentrations of dl-PCB in the mostly gaseous fraction (using quarterly passive samplers) and greater concentrations of PCDD/F in the mostly particle fraction (using daily active samplers). Dioxin-like PCB predominance was associated with the semi-volatility property, which depends on ambient temperature. Slight variations of ambient temperature in Manizales during the sampling period (15 °C–27 °C) may have triggered higher concentrations in all passive samples.This was the first passive air sampling monitoring of PCDD/F conducted in an urban area of Colombia. Passive sampling revealed that PCDD/F in combination with dioxin-like PCB ranged from 16 WHO-TEQ2005/m3 near industrial sources to 7 WHO-TEQ2005/m3 in an intermediate zone—a reduction of 56% over 2.8 km. Active sampling of particulate phase PCDD/F and dl-PCB were analyzed in PM10 samples. PCDD/F combined with dl-PCB ranged from 46 WHO-TEQ2005/m3 near vehicular sources to 8 WHO-TEQ2005/m3 in the same intermediate zone, a reduction of 83% over 2.6 km. Toxic equivalent quantities in both PCDD/F and dl-PCB decreased toward an intermediate zone of the city.Variations in congener profiles were consistent with variations expected from nearby sources, such as a secondary metallurgy plant, areas of concentrated vehicular emissions and a municipal solid waste incinerator (MSWI). These variations in congener profile measurements of dioxins and dl-PCBs in passive and active samples can be partly explained by congener variations expected from the various sources.