Evaluation of the relative health risk impact of atmospheric PCDD/Fs in PM_2.5 in Taiwan

Many studies have indicated that the largest amounts of particle-bound polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are found on small particles, which result in them having the highest PCDD/F TEQ concentrations. Epidemiological studies have found associations between PCDD/F exposure and development of many chronic diseases such as cardiovascular disease or cancers even in low exposure populations. Recently, in many countries, the concentrations of PM_2.5 and PCDD/Fs have been one of the main foci of air monitoring systems. Several researches have suggested an association between air pollutants and health outcomes. However, publications about how PM_2.5 and PCDD/Fs influence the health outcome in Taiwan are still limited. In this research, the spatial concentrations of PCDD/Fs in the vapor phase and the solid phase (TSP and PM_2.5) were investigated during the winter seasons from 2012 to 2014 at different sites in Taiwan. The mean PCDD/F concentrations ranged from 10.8 ± 11.0 to 135 ± 64.3 fg I-TEQ m^–3, with the highest concentrations found in the samples collected at industrial parks. Over 45.5% to 73.8% of the total PCDD/F concentrations were partitioned in the solid phase, while about 35.2% to 86.3% were distributed in PM_2.5. The total quantities of the PCDD/F TEQs adsorbed onto PM_2.5 measured at one northern urban sampling site (1,180 ± 294 pg I-TEQ g-PM_2.5 ^–1) and one northern suburban sampling site (1,110 ± 574 pg I-TEQ g-PM_2.5 ^–1) were higher than at other sites due to the influence of local municipal solid waste incinerators and long-range transport. Moreover, a significantly higher mortality risk was found for people living in areas with higher exposure rates of PM_2.5 and PCDD/Fs.