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Technical Papers

Identification of the sources of PM10 in a subway tunnel using positive matrix factorization

, , , , , , & show all
Pages 1361-1368 | Received 10 Apr 2014, Accepted 26 Jul 2014, Published online: 14 Nov 2014
 

Abstract

The level of particulate matter of less than 10 μm diameter (PM10) at subway platforms can be significantly reduced by installing a platform screen-door system. However, both workers and passengers might be exposed to higher PM10 levels while the cars are within the tunnel because it is a more confined environment. This study determined the PM10 levels in a subway tunnel, and identified the sources of PM10 using elemental analysis and receptor modeling. Forty-four PM10 samples were collected in the tunnel between the Gireum and Mia stations on Line 4 in metropolitan Seoul and analyzed using inductively coupled plasma–atomic emission spectrometry and ion chromatography. The major PM10 sources were identified using positive matrix factorization (PMF). The average PM10 concentration in the tunnels was 200.8 ± 22.0 μg/m3. Elemental analysis indicated that the PM10 consisted of 40.4% inorganic species, 9.1% anions, 4.9% cations, and 45.6% other materials. Iron was the most abundant element, with an average concentration of 72.5 ± 10.4 μg/m3. The PM10 sources characterized by PMF included rail, wheel, and brake wear (59.6%), soil combustion (17.0%), secondary aerosols (10.0%), electric cable wear (8.1%), and soil and road dust (5.4%). Internal sources comprising rail, wheel, brake, and electric cable wear made the greatest contribution to the PM10 (67.7%) in tunnel air.

Implications

With installation of a platform screen door, PM10 levels in subway tunnels were higher than those on platforms. Tunnel PM10 levels exceeded 150 μg/m3 of the Korean standard for subway platform. Elemental analysis of PM10 in a tunnel showed that Fe was the most abundant element. Five PM10 sources in tunnel were identified by positive matrix factorization. Railroad-related sources contributed 68% of PM10 in the subway tunnel.

Additional information

Notes on contributors

Duckshin Park

Duckshin Park is a principal researcher and Doyeon Hwang, Wonseok Jung, and Yongil Lee are researchers at Korea Railroad Research Institute, Uiwang, Korea.

Taejeong Lee

Taejeong Lee is a research assistant professor and Dongsool Kim is a professor at Kyung Hee University, Yongin, Korea.

Doyeon Hwang

Duckshin Park is a principal researcher and Doyeon Hwang, Wonseok Jung, and Yongil Lee are researchers at Korea Railroad Research Institute, Uiwang, Korea.

Wonseok Jung

Duckshin Park is a principal researcher and Doyeon Hwang, Wonseok Jung, and Yongil Lee are researchers at Korea Railroad Research Institute, Uiwang, Korea.

Yongil Lee

Duckshin Park is a principal researcher and Doyeon Hwang, Wonseok Jung, and Yongil Lee are researchers at Korea Railroad Research Institute, Uiwang, Korea.

KiChul Cho

KiChul Cho is an associate professor at Dongnam Health College, Suwon, Korea.

Dongsool Kim

Taejeong Lee is a research assistant professor and Dongsool Kim is a professor at Kyung Hee University, Yongin, Korea.

Kiyoung Lee

Kiyoung Lee is a professor at Seoul National University, Seoul, Korea.

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