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A large-scale monitoring program, the Asia Soil and Air Monitoring Program (Asia-SAMP), was conducted in five Asian countries, including China, Japan, South Korea, Vietnam, and India. Air samples were collected using passive air samplers with polyurethane foam disks over four consecutive 3-month periods from September 2012 to August 2013 to measure the seasonal concentrations of 47 polycyclic aromatic hydrocarbons (PAHs), including 21 parent and 26 alkylated PAHs, at 176 sites (11 background, 83 rural, and 82 urban). The annual concentrations of total 47 PAHs (∑47PAHs) at all sites ranged from 6.29 to 688 ng/m(3) with median of 82.2 ng/m(3). Air concentrations of PAHs in China, Vietnam, and India were greater than those in Japan and South Korea. As expected, the air concentrations (ng/m(3)) were highest at urban sites (143 ± 117) followed by rural (126 ± 147) and background sites (22.4 ± 11.4). Significant positive correlations were found between PAH concentrations and atmosphere aerosol optical depth. The average benzo(a)pyrene equivalent concentration (BaPeq) was 5.61 ng/m(3). It was estimated that the annual BaPeq concentrations at 78.8% of the sampling sites exceeded the WHO guideline level. The mean population attributable fraction (PAF) for lung cancer due to inhalation exposure to outdoor PAHs was on the order 8.8‰ (0.056-52‰) for China, 0.38‰ (0.007-3.2‰) for Japan, 0.85‰ (0.042-4.5‰) for South Korea, 7.5‰ (0.26-27‰) for Vietnam, and 3.2‰ (0.047-20‰) for India. We estimated a number of lifetime excess lung cancer cases caused by exposure to PAHs, which the concentrations ranging from 27.8 to 2200, 1.36 to 108, 2.45 to 194, 21.8 to 1730, and 9.10 to 720 per million people for China, Japan, South Korea, Vietnam, and India, respectively. Overall, the lung cancer risk in China and Vietnam were higher than that in Japan, South Korea, and India.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are a group of compounds of major environmental concern. Once emitted into the atmosphere, PCDD/Fs undergo photochemical reactions and enter other environmental compartments via wet and dry deposition. In this study, atmospheric PCDD/F depositions were collected via an automated PCDD/F deposition sampler and traditional cylindrical vessels, respectively, in northern, central, and southern Taiwan from 2008 to 2010. The automated PCDD/F precipitation sampler used in this study can prevent both resuspension and photodegradation of the PCDD/Fs collected and also effectively separates the PCDD/F samples into dry and wet contributions. The results indicate that the average atmospheric PCDD/F concentrations collected by the high-volume sampling trains were 13.6 ± 10 (n = 10), 15.6 ± 5.2 (n = 7), and 10.9 ± 6.3 (n = 6) fg I-TEQ/m(3) in northern, central, and southern Taiwan, respectively. In addition, the results also indicate that the PCDD/F deposition flux collected with an automated PCDD/F sampler (1.84 ± 0.90-8.68 ± 5.1 pg I-TEQ/m(2)/day, n = 23) is significantly higher than that sampled with cylindrical vessels (1.11 ± 0.69-5.64 ± 5.2 pg I-TEQ/m(2)/day, n = 23). Based on the Mann-Whitney statistical analysis, the p value (0.037) of PCDD/F deposition flux between those two samplers measurement is lower than 0.05. The difference is attributed to the fact that part of the PCDD/F depositions collected by traditional cylindrical vessels is photodegraded and revolatilized. In addition, the wet deposition flux of PCDD/Fs (3.66 to 470 pg I-TEQ/m(2)/rainy day, n = 23) observed in Taiwan is significantly higher than the dry deposition flux (0.38 to 4.55 pg I-TEQ/m(2)/sunny day, n = 23). The results demonstrate that the wet deposition is the major PCDD/F removal mechanism in the atmosphere. Furthermore, the overall PCDD/Fs deposition velocity and scavenging (rainout) coefficient in Taiwan are calculated as 0.20 ± 0.07 cm/s and 6.5 ± 0.2 × 10(4), respectively.

Recent biomass burning in Southeast Asia has raised global concerns over its adverse effects on visibility, human health, and global climate. The concentrations of total suspended particles (TSPs) and other vapor-phase pollutants (CO and ozone) were monitored at Lulin, an atmospheric background station in central Taiwan in 2008. To evaluate the long-range transport of persistent organic pollutants (POPs) during the Southeast Asia biomass burning event, the atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were also measured at Lulin station. The atmospheric PCDD/F and TSP concentrations measured at Lulin station ranged from 0.71-3.41 fg I-TEQ/m(3) and 5.32-55.6 microg/m(3), respectively, during the regular sampling periods. However, significantly higher concentrations of PCDD/Fs, TSPs, CO, and ozone were measured during the spring season. These high concentrations could be the result of long-range transport of the products of Southeast Asia biomass burning. During the Southeast Asia biomass burning event (March 18-24, 2008), an intensive observation program was also carried out at the same station. The results of this observation program indicated that the atmospheric PCDD/F concentration increased dramatically from 2.33 to 390 fg I-TEQ/m(3) (March 19, 2008). The trace gas (CO) of biomass burning also significantly increased to 232 ppb during the same period, while the particle-bound PCDD/Fs in the TSP increased from 28.7 to 109 pg I-TEQ/g-TSP at Lulin station during the burning event. We conclude that there was a significant increase in the PCDD/F concentration in ambient air at a high-altitude background station in central Taiwan during the Southeast Asia biomass burning event.

A PCDD/F(polychlorinated dibenzo-p-dioxin and dibenzofuran)-containing gas stream generating system was developed to investigate the efficiency and effectiveness of V2O5-WO3 catalyst for PCDD/F destruction. Catalytic decomposition of PCDD/Fs (simulated gas streams) was evaluated with lab-scale pelletized and plate-type catalyst based on V2O5-WO3/TiO2 at controlled temperature, space velocity, and inlet PCDD/F concentration. Due to the lower porosity of the pelletized catalyst PCDD/F destruction efficiencies reach 72.9-83.2% for different levels of inlet PCDD/F concentrations (1.08-3.04 ng-TEQ/Nm3) of the gas stream (space velocity: 5000 h(-1)). As the surface area is increased from 287 m2/m3 (plate-type A) to 550 m2/m3 (plate-type B), the PCDD/F destruction achieved with plate-type catalyst increases from 76.0% to 85.3% at 320 degrees C (space velocity: 5000 h(-1)). In addition, the results of pilot-scale experiment (real flue gases of a sinter plant) indicate that relatively lower PCDD/F destruction efficiencies (62.1-65.7%) were achieved with the plate-type B catalyst as the solid-phase PCDD/F and fly ash passed through the reactor (space velocity: 5000 h(-1)). Overall, the lab-scale and pilot-scale experiments indicate that PCDD/F destructions achieved with pelletized and plate-type catalysts strongly depend on the operating temperature of the catalyst. The results also indicate that the presence of fly ash the lowers PCDD/F destruction due to significant PCDD/F formation via de novo synthesis at 320 degrees C.

Catalytic destruction has been applied to control polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) emissions from different facilities. The cost of carbon-based catalysts is considerably lower than that of the metal oxide or zeolite-based catalysts used in the selective catalytic reduction (SCR) system. In this study, destruction and adsorption efficiencies of PCDD/Fs achieved with Cu/C and Fe/C catalysts from flue gas streams of a metal smelting plant (MSP) and a large-scale municipal waste incinerator (MWI), respectively, are evaluated via the pilot-scale catalytic reactor system (PCRS). The results indicate that Cu and Fe catalysts supported on carbon surface are capable of decomposing and adsorbing PCDD/ Fs from gas streams. In the testing sources of MSP and MWI, the PCDD/F removal efficiencies achieved with Cu/C catalyst at 250 degrees C reach 96%, however, the destruction efficiencies are negative (-1,390% and -112%, respectively) due to significant PCDD/F formation on catalyst promoted by copper. In addition, Fe/C catalyst is of higher removal and destruction efficiencies compared with Cu/C catalyst in both testing sources. The removal efficiencies of PCDD/Fs achieved with Fe/C catalyst are 97 and 94% for MSP and MWI, respectively, whereas the destruction efficiencies are both higher than 70%. Decrease of PCDD/F destruction efficiency and increase of adsorption efficiency with increasing chlorination of dioxin congeners is also observed in the test via three-layer Fe/C catalyst. Furthermore, the mass of 2,3,7,8-PCDD/Fs retained on catalyst decreases on the order of first to third layer of catalyst. Each gram Fe/C catalyst in first layer adsorbs 10.9, 6.91, and 3.04 ng 2,3,7,8-PCDD/Fs in 100 min testing duration as the operating temperature is controlled at 150, 200, and 250 degrees C, respectively.

Previous study indicates that the polychlorinated dibenzo-p-dioxin and -dibenzofurans (PCDD/F) concentration measured in the stack gas of the Waelz plant investigated reached 194 ng-TEQ/(N m3) (TEQ = toxic equivalence), due to the relatively high potential of PCDD/F formation and a low PCDD/F removal efficiency (<70%) achieved with the baghouse filter (BF). In September 2006, the Taiwan government setthe PCDD/F emission limit for existing Waelz plants as 1.0 ng-I-TEQO/(N m3). The retrofit technology for reducing PCDD/F emissions from the existing Waelz plant was evaluated at the same time. Carbon-type adsorbent injection technology was adopted in early 2006 to reduce the emission of dioxin-like compounds at the Waelz plant investigated. Flue gases and ambient air samplings were conducted during the two stages of retrofit to evaluate the removal efficiency of dioxin-like compounds at the Waelz plant investigated. At stage 1, by applying adsorbent injection + single baghouse filter (SBF), the PCDD/F and polychlorinated biphenyl (PCB) concentrations measured in the stack gas at the Waelz plant were 4.62 ng-TEQ/(N m3) and 0.08 ng-TEQ(WHO)/(N m3) (TEQ(WHO) = World Health Organization TEQ), respectively, as the adsorbent injection rate was controlled at 40 kg/h (or 540 mg/ (N m3)). At stage 2, the PCDD/F and PCB concentration measured at stack gas, achieved with adsorbent injection + dual baghouse filter (DBF) system, were further reduced to 0.235 + 0.04 ng-I-TEQ/(N m3) (I-TEQ = International TEQ) and 0.004 + 0.002 ng-TEQ(WHO)/(N m3) with the adsorbent injection rate at 16 kg/h (or 215 mg/(N m3)). In the meantime, the atmospheric PCDD/F concentrations measured in the vicinity area of the Waelz plant were greatly reduced from 568-1465 to 48.9-130 fg-I-TEQ/m3. Higher removal efficiency (>99.8%) achieved at a lower adsorbent injection rate (16 kg/h) of the adsorbent injection + DBF system also significantly reduced the total PCDD/-F and PCB emission flows (per kg of electric arc furnace dust treated) to 1925 ng-I-TEQ and 30.5 ng-TEQ(WHO), respectively.

Significant formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) has been observed in a typical Waelz process plant. In 2005, the Waelz plant investigated was equipped with a dust settling chamber (DSC), a venturi cooling tower, a cyclone (CY), and baghouse filter (BF). In early 2006 activated carbon injection (ACI) was adopted to reduce PCDD/F emissions from the plant investigated. Samplings of flue gases and ash were simultaneously conducted at different sampling points in the Waelz plantto evaluate removal efficiency and partitioning of PCDD/Fs between the gas phase and particulates. As the operating temperature of the dust settling chamber (DSC) is increased from 480 to 580 degrees C, the PCDD/F concentration measured at the DSC outlet decreases from 1220 to 394 ng-l-TEQ/Nm3. By applying ACI, the PCDD/F concentrations of stack gas decrease from 139-194 to 3.38 ng-l-TEQ/ Nm(3) (a reduction of 97.6-98.3%) while the PCDD/F concentration of reacted ash increases dramatically from 0.97 to 29.4 ng-l-TEQ/g, as the activated carbon injection rate is controlled at 40 kg/h. Additionally, ambient air PCDD/F concentrations were measured in the vicinity of this facility during different operating stages (shutdown, and operation with and without ACI). The ambient PCDD/F concentration measured downwind and 2.5 km from the Waelz plant decreases from 568 to 206 fg-I-TEQ/m(3) after ACI has been applied to collect the dioxins. Due to the high PCDD/F removal efficiency achieved with ACI + BF, about 24.3 and 3980 ng-l-TEQ/kg EAF-dust treated are discharged via stack gas and reacted ash, respectively, in this facility.

The Waelz process is a classic method used for recovering zinc from electric arc furnace (EAF) dusts containing relatively high concentrations of PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) as well as volatile metals, such as Zn, Pb, and Cu, and chlorine. As a result of the operating temperature in the cooling process and high carbon and chlorine contents, significant PCDD/Fs are formed in the typical Waelz process, causing public concerns regarding PCDD/F emissions. In this study, flue gas and ash samplings are simultaneously conducted at different sampling points to evaluate the removal efficiency and the partitioning of PCDD/Fs between the vapor and solid phases in the Waelz plant investigated. With the environment (temperature window, sufficient retention time, chlorine, and catalysts available) conducive to PCDD/F formation in the dust settling chamber (DSC), a significantly high PCDD/F concentration (1223 ng TEQ/Nm3) is measured in flue gas downstream from the DSC of the Waelz plant investigated. In addition, the cyclone and bag filter adopted in this facility can only remove 51.3% and 69.4%, respectively, of the PCDD/Fs in the flue gas, resulting in a high PCDD/F concentration (145 ng TEQ/Nm3) measured in the stack gas of the Waelz plant investigated. On the basis of treating 1 ton of EAF dust, the total PCDD/F discharge (stack gas emission + ash discharge) is 840 ng TEQ/kg EAF dust of the Waelz plant investigated. Because of the lack of effective air pollutant control devices for PCDD/Fs, about 560 ng TEQ/kg EAF dust are discharged via stack gas in this facility.

Activated carbon injection (ACI) is commonly used to control PCDD/F (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) emissions from stationary sources. In this study, the characteristics of PCDD/Fs emitted from one municipal waste incinerator (MWI) and two industrial waste incinerators (IWI-1 and IWI-2) that apply activated carbon systems for controlling the emissions are investigated via intensive stack sampling. MWI and IWI-1 are equipped with ACI and bag filters (BF) while IWI-2 is equipped with a fixed activated carbon bed (FCB). Results indicate that most PCDD/Fs in flue gas downstream of ACI+BF exist in vapor phase (over 90%) while most PCDD/ Fs exist in solid phase (over 60%) downstream of FCB. For MWI and IWI-1, the removal efficiencies of vapor and solid-phase PCDD/Fs are 98.5-99.6% and 99.8-99.9%, respectively. In addition,the removal efficiencies of vapor- and solid-phase PCDD/Fs are 84.5% and -13.4% in IWI-2, respectively. The results also indicate that the partition of vapor/solid-phase PCDD/F is affected by the type of the air pollutant control devices (APCDs) applied upstream and the particulate matter concentration in flue gas. On the basis of the sampling results of waste incinerators, this study preliminarily establishes the equations for predicting vapor/solid-phase PCDD/F partition in flue gases downstream of various APCDs including cyclone (CY), electrostatic precipitator (EP), FCB, ACI+BF, and selective catalytic reduction system (SCR).