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Open AccessArticle

Application of Positive Matrix Factorization in the Identification of the Sources of PM2.5 in Taipei City

Department of Environmental Protection, Taipei City Government, 6 Floor, No. 1, City Hall Road, Taipei 110, Taiwan
College of Public Health, National Taiwan University, No. 17, Xu-Zhou Road, Taipei 100, Taiwan
Sinotech Engineering Services, Ltd., 12 Floor, No. 171, Section 5, Nanjing E. Road, Songshan District, Taipei 105, Taiwan
Author to whom correspondence should be addressed.
Int. J. Environ. Res. Public Health 2018, 15(7), 1305;
Received: 19 April 2018 / Revised: 15 June 2018 / Accepted: 15 June 2018 / Published: 21 June 2018
(This article belongs to the Section Environmental Health)
Fine particulate matter (PM2.5) has a small particle size, which allows it to directly enter the respiratory mucosa and reach the alveoli and even the blood. Many countries are already aware of the adverse effects of PM2.5, and determination of the sources of PM2.5 is a critical step in reducing its concentration to protect public health. This study monitored PM2.5 in the summer (during the southwest monsoon season) of 2017. Three online monitoring systems were used to continuously collect hourly concentrations of key chemical components of PM2.5, including anions, cations, carbon, heavy metals, and precursor gases, for 24 h per day. The sum of the concentrations of each compound obtained from the online monitoring systems is similar to the actual PM2.5 concentration (98.75%). This result suggests that the on-line monitoring system of this study covers relatively complete chemical compounds. Positive matrix factorization (PMF) was adopted to explore and examine the proportion of each source that contributed to the total PM2.5 concentration. According to the source contribution analysis, 55% of PM2.5 can be attributed to local pollutant sources, and the remaining 45% can be attributed to pollutants emitted outside Taipei City. During the high-PM2.5-concentration (episode) period, the pollutant conversion rates were higher than usual due to the occurrence of vigorous photochemical reactions. Moreover, once pollutants are emitted by external stationary pollutant sources, they move with pollution air masses and undergo photochemical reactions, resulting in increases in the secondary pollutant concentrations of PM2.5. The vertical monitoring data indicate that there is a significant increase in PM2.5 concentration at high altitudes. High-altitude PM2.5 will descend to the ground and thereby affect the ground-level PM2.5 concentration. View Full-Text
Keywords: PM2.5; online monitoring; vertical profile; photochemical reaction; PMF PM2.5; online monitoring; vertical profile; photochemical reaction; PMF
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Ho, W.-Y.; Tseng, K.-H.; Liou, M.-L.; Chan, C.-C.; Wang, C.-H. Application of Positive Matrix Factorization in the Identification of the Sources of PM2.5 in Taipei City. Int. J. Environ. Res. Public Health 2018, 15, 1305.

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