Installation of platform screen doors and their impact on indoor air quality: Seoul subway trains

Abstract

In this study, variations of particulate matter (PM) concentrations in subway trains following installation of platform screen doors (PSDs) in the Seoul subway system were investigated. PM samples were collected in the trains on subway lines 1-8 before and after installation of PSDs. It was found that the mean PM 10 concentration in the trains after PSDs installation increased significantly by 29.9% compared to that before installation. In particular, the increase of PM 10 in line 6 was the highest at 103%. When the relationship between PM 10 and PM 2.5 was compared, coefficients of determination (r 2 ) before and after PSDs installations were 0.696 and 0.169, respectively. This suggests that air mixing between the platform and the tunnel after PSDs installation was extremely restricted. In addition, the indoor/outdoor PM 10 ratio following PSDs installation increased from 1.32 to 2.97 relative to the period with no installed PSDs. Furthermore, this study revealed that PM levels in subway trains increased significantly after all underground PSDs were put in use. Several potential factors were examined that could result in this PM increase, such as train ventilation systems, operational conditions, passenger volume, subway depth, and the length of underground segments.Implications: PM 10 concentrations inside the subway trains increased after PSDs installation. This indicates that air quality in trains was very seriously impacted by PSDs. PM 10 levels were also influenced by the tunnel depth and length of the underground segments. To prevent the adverse effect on human health by PM 10 emitted from the tunnel, an applicable ventilation system to reduce PM 10 is required inside trains and tunnels.

A review of traditional and advanced technologies for the removal of particulate matter in subway systems

“…This means that the fine dust that is rescattered by the train entering the platform from the tunnel is blocked by the PSDs. 50 Additionally, Son et al 26 confirmed that the PM 10 levels in the train increased to 29.9%-103% after the installation of PSDs. In addition, Jung et al 54 reported that iron-containing particles generated from the tunnel were significantly reduced in the platform after the PSDs were installed.…”

“…[26][27][28][29][30][31][32] It is also known that the PM generated by the subway operation is caused by mechanical phenomena (such as wear due to friction and scratching between the rail and wheels, and between the pantograph and the subway trains) and is floated by the train-induced wind. [26][27][28][29][30][31][32] It is also known that the PM generated by the subway operation is caused by mechanical phenomena (such as wear due to friction and scratching between the rail and wheels, and between the pantograph and the subway trains) and is floated by the train-induced wind.…”

“…The train passing through the tunnel has a double effectpushing the air in front and suctioning the air from the rear with a negative vortex pressure. 26 To solve this problem, it is necessary to improve the old ventilation system and to operate it properly. 34 Thus, optimal use of the piston effect can provide significant energy savings.…”

“…34 Thus, optimal use of the piston effect can provide significant energy savings. 26 Accordingly, it is estimated that the air supply ventilation system installed in parks and green areas can reduce the indoor air pollution level in the subway space by introducing a supply of clean air. 50 However, in the case of forced ventilation, appropriate use and management are necessary to solve civil complaints caused by noise, aging, improper design, and high operating costs.…”

“…50 However, in the case of forced ventilation, appropriate use and management are necessary to solve civil complaints caused by noise, aging, improper design, and high operating costs. 26 Therefore, further studies on the reduction of pollutant discharged through the ventilation should be performed. As an example, Son et al 12 operating savings of the order of one-third compared to current management practices, concluding that SDP is the best choice.…”