Characteristics of PM2.5 and Black Carbon Exposure Among Subway Workers

Abstract

This study aimed to assess the characteristics of exposure to both PM2.5 and black carbon (BC) among subway workers. A total of 61 subway workers, including 26, 23, and 12 subway station managers, maintenance engineers, and train drivers, respectively, were investigated in 2018. Real-time measurements of airborne PM2.5 and BC were simultaneously conducted around the breathing zones of workers. Maintenance engineers had the highest average levels of exposure to both PM2.5 and BC (PM2.5, 76 µg/m3; BC, 9.3 µg/m3), followed by train drivers (63.2 µg/m3, 5.9 µg/m3) and subway station managers (39.7 µg/m3, 2.2 µg/m3). In terms of the relationship between mass concentrations of PM2.5 and BC, train drivers demonstrated the strongest correlation (R = 0.72), indicating that the proportion of BC contained in PM2.5 is relatively steady. The average proportion of BC in PM2.5 among maintenance engineers (13.0%) was higher than that among train drivers (9.4%) and subway station managers (6.4%). Univariate and mixed effect multiple analyses demonstrated the type of task and worksite to be significant factors affecting exposure levels in maintenance engineers and subway station managers. The use of diesel engine motorcars in tunnel maintenance was found to be a key contributor to PM2.5 and BC exposure levels among subway workers.

PM2.5 Concentration and Composition in Subway Systems in the Northeastern United States

“…Our measurements and analyses reveal variable and, in places, very high PM 2:5 exposures of commuters and transit workers in the underground subway systems of northeastern U.S. cities. The most extreme exposure, identified in a subway station on the PATH system (serving NJ and NYC), was higher than the previously published values for any subway station in the world (Martins et al 2016;Moreno et al 2017;Qiu et al 2017;Van Ryswyk et al 2017;Xu and Hao 2017;Lee et al 2018;Minguillón et al 2018;Mohsen et al 2018;Moreno and de Miguel 2018;Choi et al 2019;Loxham and Nieuwenhuijsen 2019;Pan et al 2019;Shen and Gao 2019;Velasco et al 2019;Smith et al 2020), with a mean gravimetric PM 2:5 concentration greater than 1,000 lg=m 3 PM 2:5 ( Figure 1). The MTA-serviced subway stations in Manhattan also had poor air quality, with an adjusted real-time mean ± SD PM 2:5 concentration of 548 ± 207 lg=m 3 .…”

“…Notably, TC, made primarily of the estimated OC component, dominated the Government Center-Blue Line aerosol, although the significance of this is unclear and further investigation into the sources of PM 2:5 and the role of the mechanical design (e.g., ventilation) of each station is needed. Notably, there was relatively little EC (or the roughly equivalent BC 2:5 ) present in any of the six underground subway stations, an unexpected finding given the emphasis that multiple papers (Vilcassim et al 2014;Choi et al 2019) have placed on inorganic carbon species. A plausible source of EC would be diesel combustion in subway systems, for example, from diesel maintenance trains that operate in the MTA system.…”

Environmental and Health Effects of Ventilation in Subway Stations: A Literature Review

“…Firstly, subway PMs are highly ferruginous (FePM) and accompanied by trace metals, such as Mn, Cr, Cu, Sb, Ba, Zn, and Mo, of which the dominant ferruginous component is typically oxidized to magnetite, maghemite, and hematite [88,90,94,96,102,103,106,110,. Secondly, carbonaceous PM is the first or second most abundant component in subways, especially platforms [110,[138][139][140][141]. Thirdly, the crustal particles (mainly silicates) are not only from the mineral dust in infiltrated outdoor air but also from construction material and rock soil inside subways.…”

Characteristics of PM10 Levels Monitored for More than a Decade in Subway Stations in South Korea

“…Studies in both New York City (Vilcassim et al, 2014) and Shanghai (Guo et al, 2017) indicated that a potential source of fine particles in subways was the diesel engine cleaning and maintenance vehicles that operated during the night in the underground facilities. Recently, Choi et al (2019) also identified that the use of diesel engine vehicles in tunnel maintenance was a key contributor to both PM 2.5 and black carbon (BC) exposure levels among subway workers. The use of diesel engine vehicles in semi-confined underground environments causes not only exposure to high levels of diesel engine exhaust emissions but also an increase in PM 2.5 on subway platforms or in waiting rooms.…”