title: Identification of the sources of PM10 in a subway tunnel using positive matrix factorization.
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.
authors.affiliation: Eco-Transport Research Division, Korea Railroad Research Institute, Uiwang, Korea.
authors.forename: Duckshin
authors.initials: D
authors.lastname: Park
authors.forename: Taejeong
authors.initials: T
authors.lastname: Lee
authors.forename: Doyeon
authors.initials: D
authors.lastname: Hwang
authors.forename: Wonseok
authors.initials: W
authors.lastname: Jung
authors.forename: Yongil
authors.initials: Y
authors.lastname: Lee
authors.forename: KiChul
authors.initials: K
authors.lastname: Cho
authors.forename: Dongsool
authors.initials: D
authors.lastname: Kim
authors.forename: Kiyoung
authors.initials: K
authors.lastname: Lees
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002852:Chromatography, Ion Exchange; D004784:Environmental Monitoring; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011890:Railroads; D013054:Spectrophotometry, Atomic
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter