Physicochemical Characterization and Oxidative Potential of Iron-Containing Particles Emitted from Xuanwei Coal Combustion.

Respiratory diseases have been proven to be directly related to air pollutants. Xuanwei, located in South China, has been known to have the highest mortality rate for lung cancer in China because of the air pollutants emitted through local coal combustion. However, the mechanism of lung cancer induced by air pollutants is not clear. Based on the fact that a large number of iron-bearing mineral particles was found in Xuanwei coal combustion particles, the iron-containing particles were hypothesized to play important roles in the pathogenesis of the high incidence rate of lung cancer in this area. In this study, raw coal samples were collected from a coal mine in the Xuanwei area. Size-resolved particles emitted from the raw coal samples were collected using an Anderson high-volume sampler. Mineralogical characterization and an assessment of the oxidative potential of the iron-containing particles were conducted using cutting-edge technologies, and the biological activity of the particles were evaluated via DTT assay. Our data showed that the iron-containing minerals accounted for more than 10% of the measured particles emitted from Xuanwei coal combustion samples. The content analysis of ·OH generated from Xuanwei coal combustion particles showed that ·OH content was dependent on the size of particles in the surrogated lung fluid. The concentration of ·OH increased as the particle size decreased. The DTT assay data further demonstrated that when the mass concentration of dissolved irons increased, the oxidation potential of the particles increased. The highest proportion of divalent iron in the total dissolved iron was found in the submicron particles in low pH solution(pH = 1), which indicated that the oxidative potential induced by submicron particles was stronger than that induced by coarse particles and fine particles. Armed with the above data, the toxicological mechanism of the iron-containing mineral particles can be investigated further.

Acute Effects of Ambient PM2.5 on All-Cause and Cause-Specific Emergency Ambulance Dispatches in Japan.

Short-term health effects of ambient PM2.5 have been established with numerous studies, but evidence in Asian countries is limited. This study aimed to investigate the short-term effects of PM2.5 on acute health outcomes, particularly all-cause, cardiovascular, respiratory, cerebrovascular and neuropsychological outcomes. We utilized daily emergency ambulance dispatches (EAD) data from eight Japanese cities (2007-2011). Statistical analyses included two stages: (1) City-level generalized linear model with Poisson distribution; (2) Random-effects meta-analysis in pooling city-specific effect estimates. Lag patterns were explored using (1) unconstrained-distributed lags (lag 0 to lag 7) and (2) average lags (lag: 0-1, 0-3, 0-5, 0-7). In all-cause EAD, significant increases were observed in both shorter lag (lag 0: 1.24% (95% CI: 0.92, 1.56)) and average lag 0-1 (0.64% (95% CI: 0.23, 1.06)). Increases of 1.88% and 1.48% in respiratory and neuropsychological EAD outcomes, respectively, were observed at lag 0 per 10 µg/m³ increase in PM2.5. While respiratory outcomes demonstrated significant average effects, no significant effect was observed for cardiovascular outcomes. Meanwhile, an inverse association was observed in cerebrovascular outcomes. In this study, we observed that effects of PM2.5 on all-cause, respiratory and neuropsychological EAD were acute, with average effects not exceeding 3 days prior to EAD onset.

Dioxin distribution characteristics and health risk assessment in different size particles of fly ash from MSWIs in China.

During the process of treating and recycling Municipal Solid Waste Incinerators (MSWIs) fly ash, polychlorinated dibenzo-p-dioxins (PCDD/Fs) and polychlorinated dibenzofurans (dl-PCBs) in fly ash may potentially mobilize in the atmosphere and be widely distributed in the environment because of the inevitable re-suspension. Thus, this work presents the distributions of PCDD/Fs and dl-PCBs in inhalable coarse particles (Dp10-2.5 (particle diameter in µm)), fine particles (Dp<2.5) of fly ash and original fly ash from four MSWI plants in China. The results show that PCDD/Fs and dl-PCBs preferentially concentrated in Dp10-2.5 and Dp<2.5. Their mass concentrations and TEQ were significantly higher than those in the original fly ash, but the distribution of PCDD/Fs congeners in Dp10-2.5 and Dp<2.5 was close to that in the original fly ash. The main TEQ contribution included 1,2,3,7,8-PeCDD, 2,3,7,8-TeCDD in PCDDs and 2,3,4,7,8-PeCDF in PCDFs for Dp10-2.5, Dp<2.5 fractions and the original fly ash. Furthermore, the mass and TEQ contribution of dl-PCBs was relatively low. In addition, compared with the fluidized bed, the samples from the grate-type furnaces had significantly lower dioxin concentrations. In terms of potential health risk, the non-carcinogenic risk of PCDD/Fs in Dp10-2.5 and Dp<2.5 were estimated at 9.87 × 10(-1) to 4.81 and 1.19-7.95. For the carcinogenic risk of PCDD/Fs, both accumulation of Hazard Quotients (HQ) in Dp10-2.5 and Dp<2.5 exceeded the threshold limit and should be considered as unacceptable risk for onsite workers. The above findings could provide data to support the risk management of MSWI fly ash during the process of recycle and disposal.

Enrichment of heavy metals in fine particles of municipal solid waste incinerator (MSWI) fly ash and associated health risk.

During the pretreatment and recycling processes, the re-suspended dust from municipal solid waste incinerator (MSWI) fly ash might pose a significant health risk to onsite workers due to its toxic heavy metal content. In this work, the morphological and mineralogical characteristics of fly ash in different particle sizes are presented. The concentrations of seven trace elements (Zn, Pb, Cu, Cd, Cr, Fe and Mn) in these samples were determined. The results show that volatile metals, such as Zn, Pb, Cu and Cd, were easily concentrated in the fine particles, especially in Dp2.5-1 and Dp1, with soluble and exchangeable substances as the main chemical species. The health risk assessment illustrated that the cumulative hazard indexes for non-carcinogenic metals in Dp10-5, Dp5-2.5, Dp2.5-1, and Dp1 were 1.69, 1.41, 1.78 and 2.64, respectively, which were higher than the acceptable threshold values (1.0). The cumulative carcinogenic risk was also higher than the threshold value (10(-6)). For the onsite workers, the relatively apparent non-carcinogenic and carcinogenic effects were from Pb and Cr, respectively. The above findings suggest that fine-grained fly ash contained a considerable amount of heavy metals and exhibited a great health risk.