Source Apportionment of PM2.5 Number Concentration and Its Association with Lung Function of Schoolchildren in Xinzhuang District
Date Issued
2014
Date
2014
Author(s)
Feng, Li-Ting
Abstract
Epidemiological studies have shown that particulate matter (PM) was associated with adverse health, especially for those with diameter ≤ 2.5μm. Previous studies have utilized the total concentration of PM2.5 to quantify the health effect of fine particles by using the regression model. The sources of PM2.5 are complicated. Although understanding the health effect of fine particle, it still needs to clarify the source of particles. Therefore, this study combined both results of source apportionment and lung function measurements of schoolchildren to investigate the relation between sources of PM2.5 and lung function indices.
Number concentration of size-segregated PM in Xinzhuang area in Taiwan from 2008/06 to 2008/08 was utilized in this study. Hourly number concentration data measured by SMPS and PMS of each size bin from 0.01 μm to 2.5 μm were analyzed by positive matrix factorization (PMF). The size distribution of source profile and time series trend of each source from PMF output, as well as the correlation between source contribution and PM species were utilized to identify sources.
In this study, five sources were identified and and they were local mix (Mix 1), fresh gasoline emission (Local gasoline), fresh diesel emission (Fresh diesel), aged vehicle emission (Aged vehicle) and transported mix (Mix 2) sources. Local mix and transported mix contributed 4.20% and 13.89% of total number concentration of PM2.5. Diurnal pattern of two mix sources did not show apparent time trend as traffic. Contribution of mix sources had moderate to high correlation with secondary species. The conditional probability function (CPF) showed that the direction of transported sources were mainly from west. Other three sources were related to traffic because their diurnal patterns were similar with the traffic trend in Taiwan. Gasoline emission reflected the usage of motor vehicles; diesel emission reflected the rush hour and off-peak times of large cars such as buses. Traffic related sources were estimated to contribute more than 80% to the PM2.5 number concentration in Xinzhuang District.
Hourly source contributions were calculated into daily mean. Mixed-effects model was used to quantify the effects of single or multiple sources to lung function FVC, FEV1, FEF25%, FEF50%, FEF75% and FEF25-75% of schoolchildren in Xinzhuang District. Local mix and fresh gasoline emissions were the local sources which were not included in the mixed-effects model analysis.
Results showed that increase of transported mix with 1-day-lag was significantly associated with 0.00008 (L) decreases of FVC; increase of transported mix with 2-day-lag was also associated with 0.00034 (L/s) decreases of FEF25% and 0.00023 (L/s) decreases of FEF50% in single-pollutant model. Considering the co-pollutants effect, increases of transported mix with 1- and 2-day-lag was significantly associated with the 0.00013 (L), 0.00016 (L) decreases of FVC; increases of transported mix with 1- and 2-day-lag was significantly associated with the 0.00010 (L) and 0.00016 (L) decreases of FEV1.
This study overcame some limitation of traditional health effect study. Using source apportionment results in health data analysis can assist in quantifying the effect of different sources to lung function, and understanding the lung function effect of particulate matter with different sizes.
Subjects
汙染源解析
細懸浮微粒
粒徑分布
肺功能
Type
thesis
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