| Summary: | 碩士 === 國立臺灣大學 === 職業醫學與工業衛生研究所 === 92 === I.
This study aimed to assess the characteristics of municipal waste incinerator’s emission in its vicinity by on site air sampling, and to understand the relationship between the compounds measured and municipal waste incinerator (MWI).
We chose three MWIs in Taipei city, and divided them into three groups. In each one we chose four sites within two kilometers from the MWI as high exposure group. In the meantime, we chose eight sites at a distance from the MWI at least three kilometers as low exposure group. According to results of recent published studies, we chose gaseous and solid dioxins in the air and heavy metals in particular matter (PM) as our targets of air sampling, and used them as the indexes of MWI’s emission. For sampling of PM, we collected PM1, PM2.5 and PM10, and analyzed their heavy metal constituents. All procedures followed the standard method of Taiwan Environmental Protection Administration. Sampling of PM in low exposure group was done only in four sites for the low exposure group.
In June 2003, the concentrations of dioxin were 0.039~0.085 pg-TEQ(I-TEF)/m3 in site 1, with a median of 0.068 pg-TEQ(I-TEF)/m3. The results of site 2 were 0.044~0.060 pg-TEQ(I-TEF)/m3, with a median of 0.049 pg-TEQ(I-TEF)/m3, and values of dioxin were 0.039~0.254 pg-TEQ(I-TEF)/m3 in site 3, with a median of 0.081 pg-TEQ(I-TEF)/m3.In September 2003, the values of dioxin were 0.044~0.066 pg-TEQ(I-TEF)/m3 in site 1, with a median of 0.053 pg-TEQ(I-TEF)/m3. The concentrations of site 2 were 0.022~0.085 pg-TEQ(I-TEF)/m3, the median was 0.053 pg-TEQ(I-TEF)/m3, and values of dioxin were 0.059~0.896 pg-TEQ(I-TEF)/m3 in site 3, the median was 0.183 pg-TEQ(I-TEF)/m3. According to the results of principal component analysis, the characteristics of dioxins sampling sites were similar to those measured in the MWIS’. We also found that the concentration of chromium in PM2.5 and PM10, concentration of nickel in PM10 and concentration of zinc in PM2.5 and PM10decreased as the distance from the MWI increased. We used linear regression models to analyze the results of sampling, we found that dioxins and zinc in PM1 and PM2.5 were significant associations (p=0.069, 0.037, 0.067) with the distance from the MWIs.
Although the concentrations of air dioxins were lower in Taipei than in previous studies, MWIs were the major source of dioxins for the 36 primary schools surrounding the incinerators. The seasons and distance may be the most important predictors of MWI emissions.
II.
There were studies about MWI’s influences on respiratory health. We tried to clarify the relationship between municipal waste incinerators (MWI) and the adverse respiratory effects.
This was a cross sectional study. We chose three MWIs in similar social economical stat. For each MWI we chose two primary schools within two kilometer from the MWI as the exposure group and two primary schools at least two kilometer from the MWI as reference group. For these 12 schools, we finished twice air sampling of gaseous and solid dioxins in June and September, and used it as the indicators for the emission of MWIs. For each MWI, we chose two schools from exposure/reference group by the results of sampling. We chose two schools with high dioxin concentration as exposure group for questionnaire survey. Two schools with low dioxin concentration were chosen as reference group. We used the written questionnaire from International Study of Asthma and Allergies in Childhood (ISAAC) in Chinese version. For each school, we randomly chose a class per grade (1st ~6th). We totally finished 1927 valid questionnaires, (1 class × 6 grades × 4 schools × 3 MWIs) and response rate was 99.6%. After the questionnaire survey, we selected half of them for pulmonary function test. We did the test at the same class, but we only did it at middle and high grades (3rd ~6th). Two technicians used dry-rolling seal system equipment to measure all students under ATS criteria (1994). We finished 683 children and response rate was 98.4%.
The result of sampling on dioxin was consistent with the prediction of distance in each group of the MWI. The values of dioxin were 0.01~0.3171 pg-TEQ(I-TEF)/m3 , mean of all exposure group was 0.053 pg-TEQ(I-TEF)/m3, the mean of all reference group was 0.030 pg-TEQ(I-TEF)/m3. When comparing two groups’ information from questionnaires, there was no discrepancy on children’s age, gender and potential air pollutants from their own houses. The mean of prevalence of asthma, were 13.9% and 11.9%, for all exposure groups and all reference groups. After controlled gender, grade, mothers education, home smoking, having hairy pet, having poultry, carpet, burning incense at home, using coil incense, molds and its odor, exposure group had higher risk than reference group (odds ratio, OR=1.46 and 95% confidence interval, 95% CI: 1.05,2.03). We found the mean value of all exposure groups was 88%(FEV1/FVC) and all references were 89%(FEV1/FVC). After controlling for gender and grade, exposure group had similar risk with reference group (odds ratio, OR=0.78 and 95% confidence interval, 95%CI: 0.37,1.66)
Emissions from MWIs might have a slightly adverse respiratory effect in children. However, the role of exposure misclassification and chance should be considered.
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