The scope of work for this project includes: 1) to update and establish the emission inventory of dioxin and heavy metals; 2) to execute the investigation for emissions from the stationary sources and the environmental ambient monitoring; 3) to review and revise the existing emission standard; 4) to provide technical services and administrative assistance for the EPA . The achievements of this project are described as below:
The total dioxin emission in Taiwan area is estimated to be 74.8 g-TEQ in 2007, which is 16% less than 2006. The major pollution sources are the electric arc furnaces and sinter plants. As for heavy metal emission, the total emission in 2007 was estimated as below: lead emission is 9.72 metric tons, cadmium emission is 1.04 metric tons, mercury emission is 1.33 metric tons and arsenic emission is 4.28 metric tons , without much difference between 2006. The major emission sources are the coal-fired power plants, electric arc furnace, waste incinerators and cement kiln.
As for the emission investigation of dioxin, the PCDD/Fs, PBDD/Fs and PBDEs from the waste combustors and electric arc furnace were investigated through this project. Based on the investigation data of PCDD/Fs, all of the waste combustors and electric arc furnace did meet the emission standard. The mass ratio of PBDD/Fs and PCDD/Fs is less than 2% and the ratio for electric arc furnace is higher than waste combustors.
As for heavy metals, the coal industry boilers and the optroelectronics industry are two major targets in the project. Based on the investigation data, the measured concentrations of heavy metal emissions are far below the limits listed in the “Stationary pollution source air pollutant emissions standards”.
As for the ambient dioxin monitoring, the principle of monitoring station selection is one monitoring station for one city and the monitoring frequency is once per season. The results showed that the range of dioxin concentration is from 0.004 pg I-TEQ/m3 to 0.134 pg I-TEQ/m3, the average concentration is 0.039 pg I-TEQ/m3. The Central air quality control area and the Yun-Chia-Nan area air quality control areas were with higher dioxin concentration. But the measured concentrations were far below the ambient air standard (0.6 pg WHO-TEQ/m3), which is stipulated by Japan (currently, it is the only ambient air dioxin standard promulgated in the world). As for the ambient heavy metal monitoring, the monitoring stations are the same as the dioxin stations and the samplers were set to 24 hours continuous sampling and PM10 samples were collected on pr-weighed glass fiber filter papers. Based on the monitoring results, the heavy metal concentration of Arsenic, Cadmium and Nickel are below the target values of European Union ambient quality which will be effective in 2012. Based on the monitoring data, it was showed that the ambient heavy metal concentration in winter is higher than its concentration in summer for the Central air quality control area and the Yun-Chia-Nan area air quality control area. These results are similar with the one in the ambient dioxin monitoring. When the PM10 concentration was high, the ambient metal concentrations also along with it rise.
Based on the analysis of dioxin audit data in 2008, a total of 12 stationary sources did not meet the emission standard, which are mostly small-medium sized incinerators. All the stationary sources that can’t meet the emission standard were fined pursuant to the “Air Pollution Control Act” and be notified to make improvements within a limited time period, to ensure the least impact to the environment.
The suggestions are: continuously conduct the pollution sources audit as well as monitoring ambient dioxin and heavy metal concentration for air quality observation stations. In addition, we also suggest to conduct the ambient dioxin and heavy metal monitoring at those areas with concentrated pollution sources, in order to understand ambient air quality and ensure public health. For those areas with high density of dioxin pollution sources, management strategy should be drafted based on the technology feasibility and risk assessment. We also recommend more field investigations regarding heavy metal emissions, and a thorough review regarding heavy metal emission control standards.