The Experts below are selected from a list of 3666 Experts worldwide ranked by ideXlab platform
Sung Ho Hwang - One of the best experts on this subject based on the ideXlab platform.
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indoor air quality assessment with respect to culturable airborne bacteria total volatile organic compounds formaldehyde pm10 co2 no2 and o3 in underground Subway Stations and parking lots
Air Quality Atmosphere & Health, 2019Co-Authors: Sung Ho Hwang, Wha Me ParkAbstract:We measured the concentrations of indoor pollutants (fine particulate matter (PM10)), culturable airborne bacteria (CAB), total volatile organic compounds (TVOCs), formaldehyde (HCHO), CO2, NO2, and O3 in Subway Stations and public parking lots at a national scale in South Korea in order to determine their possible relationships with other underground environmental factors and facility characteristics. Indoor pollutants were sampled at 59 underground facilities with a total of 187 samples in Subway Stations and parking lots. Kruskal–Wallis and Mann–Whitney analyses were used to examine the relationships between atmospheric pollutants at underground facilities and indoor/outdoor differences in PM10 and O3 concentrations. Underground PM10 concentrations were higher than outdoor concentrations at all underground facilities (p < 0.001), while underground O3 concentrations were lower than outdoor O3 concentrations at all underground facilities (p < 0.001).
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factors affecting ambient endotoxin and particulate matter concentrations around air vents of Subway Stations in south korea
Chemosphere, 2018Co-Authors: Wha Me Park, Donguk Park, Sung Ho HwangAbstract:Abstract Levels of airborne endotoxins and particulate matter less than 10 μm and 2.5 μm in diameter (PM) were measured in the air vents of Subway Stations in Seoul, South Korea, and factors affecting both pollutants were analyzed. The measurements were completed from March 2016 to February 2017 for eight air vents situated at the ground level around the Subway Stations. A total of 166 air samples were collected and analyzed using the kinetic limulus amebocyte lysate assay. Endotoxin levels ranged from not detected to 1.986 EU m−3, with a mean of 0.227 EU m−3. The results showed significantly different PM levels from the measurements reported by AIRKOREA as part of the comprehensive air quality index. This can be attributed to different sampling sites in the same area. Endotoxin levels tended to be higher in fall compared to summer. Airborne bacteria levels showed a pattern similar to the endotoxin levels, but no significant association was reported between them. The levels of endotoxins around air vents with a glass cover and streets that allowed smoking were significantly higher than those not containing a walled barrier and streets in which smoking was prohibited. Multivariate regression analysis showed that the factors affecting endotoxin levels comprised air vents with a glass cover (coefficient = 0.106, p = 0.014) and season (coefficient = 0.062, p
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evaluation of airborne fungi and the effects of a platform screen door and station depth in 25 underground Subway Stations in seoul south korea
Air Quality Atmosphere & Health, 2016Co-Authors: Sung Ho Hwang, Jun Ho ChoAbstract:This study evaluated culturable airborne fungi (CAF) concentrations in indoor air at 25 underground Subway Stations in Seoul, South Korea, and assessed factors that influence those concentrations, including the presence of platform screen doors (PSD), the depth of the station, year of construction, temperature, and relative humidity. A total of 80 air samples were collected from the Stations. Fungi communities in the air samples were predominately composed of the members of the genera Penicillium, Aspergillus, Cladosporium, and Mucor. CAF concentrations ranged from under detectable limit (UDL) to 27,856 CFU/m3, and the average is 864 CFU/m3. Concentrations at 9 of the 25 Subway Stations (36 %) exceeded the Indoor Air Quality Association (IAQA) recommendation (300 CFU/m3), and 4 Stations (16 %) exceeded 1000 CFU/m3 (OSHA’s contamination guideline for airborne fungi). CAF concentrations of Stations without PSD were higher than those with PSD, albeit not statistically significantly so. CAF concentrations of wet Stations were significantly higher than those of dry Stations. Moreover, the CAF concentrations were positively correlated with the depths of Stations (r = 0.237, p < 0.05). Finally, parts of underground Subway Stations showed the contaminated level of airborne fungi and the source of airborne fungi seemed to be within the indoor space of the Subway Stations. Strategies aimed at reducing airborne fungi level may be most effective, when Stations are located at deeper depth dehumidifying measures.
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relationship between culturable airborne bacteria concentrations and ventilation systems in underground Subway Stations in seoul south korea
Air Quality Atmosphere & Health, 2016Co-Authors: Sung Ho Hwang, Wha Me Park, Jae Kyoung Ahn, Kyung Jong Lee, Kyoungbok Min, Jae Bum ParkAbstract:In this study, we evaluated the concentrations of culturable airborne bacteria (CABs) in the underground environment of 16 Subway Stations in Seoul, South Korea. The effects of environmental factors on CAB distributions and concentrations, including temperature, relative humidity, depth, year of construction, number of Subway passengers, and ventilation, were investigated. Tryptone soy agar was used as the culture medium. Isolated bacteria were initially characterized according to cell morphology and Gram staining and then further characterized using the VITEK 2 XL microbial identification system. There were significant correlations between CAB concentrations and station temperature, depth, and construction year. Micrococcus and Staphylococcus species accounted for 66 % of the total number of CABs identified. CAB concentrations in Stations with ventilation systems were significantly lower than those in Stations without ventilation systems (p < 0.001). Thus, it is critical to develop techniques to improve indoor air quality in Subway Stations with no ventilation system.
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comparison of culturable airborne bacteria and related environmental factors at underground Subway Stations between 2006 and 2013
Atmospheric Environment, 2014Co-Authors: Sung Ho Hwang, Jae Bum ParkAbstract:Abstract In this study, we evaluated concentrations of culturable airborne bacteria (CAB) from 16 underground Subway Stations of Seoul Metro, Korea, between 2006 and 2013 to identify influential environmental factors, including the presence of platform screen doors (PSD), temperature, relative humidity, depth of the station, and year of construction. In total, 66 air samples were collected from all Stations. Results indicated that CAB concentrations and the number of gram-negative bacteria (GNB) were significantly lower in Stations with PSD and in which GNB were not detected than in Stations lacking PSD and in which GNB were detected. Although there was no significant difference in CAB concentrations with variations in time, CAB concentrations of Stations appeared to alter with time due to variation in the number of passengers in transit; indeed, there was a significant association between CAB concentration and the number of passengers passing through a station. The source of CAB seemed to be the poor air quality in the old Subway Stations. Therefore, ventilation management should be inspected more regularly, and indoor air quality should be controlled in underground Subway Stations.
Xingxing Zhang - One of the best experts on this subject based on the ideXlab platform.
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analysis and interpretation of the particulate matter pm10 and pm2 5 concentrations at the Subway Stations in beijing china
Sustainable Cities and Society, 2019Co-Authors: Song Pan, Jiaping Liu, Fei Pei, Xingxing Zhang, Xinru Wang, Liang Xia, Yixuan WeiAbstract:Abstract The particulate matters (PM10 and PM2.5) inside urban Subway Stations greatly influence indoor air quality and passenger comfort. This study aims to analyze and interpret the concentrations of PM10 and PM2.5, measured in several Subway Stations from October 9th to 22nd, 2016 in Beijing, China. The overall methodology was based on the Statistical Package for Social Science (SPSS) software while General linear model (GLM) and correlation analysis were further applied to examine the sensitivities of different variables to the particle concentrations. The data analysis showed the average overall mass ratio of PM concentrations inside Subway station is about 68.7%, much lower than outdoor condition (79.6%). In the areas of the station hall and platform, the real-time PM10 and PM2.5 concentrations varied periodically. In working and operation offices, all rooms had much higher PM concentrations than the outdoor environment when its pollution level was level 3, in which the facility room reached the highest level, while the closed meeting room had the lowest. Correlation analysis results indicated that PM10 and PM2.5 concentrations were mutually correlated (average R2 = 0.854), and a strong linear correlation (R2 = 0.897) of the Subway-station PM concentrations to the outdoor PM conditions, regardless of the outdoor atmospheric PM concentrations pollution level was. Nevertheless, the impact of passenger number and temperature & humidity on the station PM concentrations was less, when compared to the outdoor environment. This paper is expected to provide useful information for further research and design of effective prevention measures on PM in local Subway Stations, towards a more sustainable and healthier built environment in the city underground.
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an investigation on energy consumption of air conditioning system in beijing Subway Stations
Energy Procedia, 2017Co-Authors: Song Pan, Hongwei Wang, Fei Pei, Le Yang, Xingxing ZhangAbstract:This paper initially depicted on the energy consumption of air conditioning systems in Beijing Subway Stations. An investigation was conducted among ten underground Subway Stations to the examinati ...
Jo-chun Kim - One of the best experts on this subject based on the ideXlab platform.
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Air Pollution Monitoring and Control System for Subway Stations Using Environmental Sensors
Journal of Sensors, 2016Co-Authors: Gyu-sik Kim, Jai Hyo Lee, Joon Tae Oh, In-won Kim, Youn-suk Son, Jo-chun Kim, Hiesik KimAbstract:The metropolitan city of Seoul uses more energy than any other area in South Korea due to its high population density. It also has high emissions of air pollutants. Since an individual usually spends most of his/her working hours indoors, the ambient air quality refers to indoor air quality. In particular, PM10 concentration in the underground areas should be monitored to preserve the health of commuters in the Subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation measure several air pollutants regularly. In this study, the accuracy of an instrument for PM measurement using the light scattering method was improved with the help of a linear regression analysis technique to continuously measure the [subscript]PM10[/subscript] concentrations in Subway Stations. In addition, an air quality monitoring system based on environmental sensors was implemented to display and record the data of PM10, CO2, temperature, and humidity. Through experimental studies, we found that ventilation fans could improve air quality and decrease PM10 concentrations in the tunnels effectively by increasing the air flow rate.
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A novel control system for nitrogen dioxide removal and energy saving from an underground Subway Stations
Journal of Cleaner Production, 2016Co-Authors: Youn-suk Son, Jin-ho Jeong, Hyung Joo Lee, Jo-chun KimAbstract:Abstract The importance of indoor air quality in a Subway system is growing rapidly because passengers' health and displeasure are interrelated. Among diverse indoor pollutants, nitrogen dioxide (NO 2 ) emitted from automobiles may flow into a platform of underground Subway through ventilation holes or stairs. The level of NO 2 in an underground Subway station should be managed to prevent its adverse effects because NO 2 is harmful to health. In this study, a novel control system (self-control system) equipped with panel-type hybrid activated carbon beds were developed and applied to remove NO 2 and save energy for ventilation from underground Subway Stations. To evaluate the removal efficiency by varying influential factors such as superficial gas velocity and relative humidity, we measured the NO 2 concentration from diverse sampling points (ambient, platform, and before and after the hybrid activated carbon bed) before and after operating the self-control system. As a result, the NO 2 concentration at the ventilation hole of the Subway station (12.3–113.6 ppb) was higher than that at the air monitoring station (9.2–68.4 ppb, AIRKOREA operated by Ministry of Environment in Korea). The level of NO 2 was changed by varying the relative humidity in ambient air. The removal efficiency of NO 2 decreased from 66.3% to 60.5% and the pressure drop of hybrid activated carbon bed in the system increased from 2.2 mmAq to 5.4 mmAq when the superficial gas velocity (depending on inverter frequency) increased from 1.04 m/s to 1.82 m/s. Additionally, the removal efficiency of NO 2 rapidly decreased with elapsed time and was affected by relative humidity and weather conditions. Finally, the level of NO 2 in the platform was less than 50 ppb (which is the standard value recommended by the Ministry of Environment, Korea), when the hybrid activated carbon bed was set to 90° (vertical direction on air flow). When the self-control system was operated in the heating ventilating, and air conditioning system of the underground Subway station, the NO 2 level in the platform was considerably controlled to below 50 ppb and the power consumption for ventilation reduced.
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chemical speciation of size segregated floor dusts and airborne magnetic particles collected at underground Subway Stations in seoul korea
Journal of Hazardous Materials, 2012Co-Authors: Hae Jin Jung, Youn-suk Son, Jo-chun Kim, Bo Wha Kim, Abdul Malek, Yong Sung Koo, Jong Hoon Jung, Hyekyoung KimAbstract:Previous studies have reported the major chemical species of underground Subway particles to be Fe-containing species that are generated from wear and friction processes at rail-wheel-brake and catenaries-pantographs interfaces. To examine chemical composition of Fe-containing particles in more details, floor dusts were collected at five sampling locations of an underground Subway station. Size-segregated floor dusts were separated into magnetic and non-magnetic fractions using a permanent magnet. Using X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), iron metal, which is relatively harmless, was found to be the dominating chemical species in the floor dusts of the <25 μm size fractions with minor fractions of Mg, Al, Si, Ca, S, and C. From SEM analysis, the floor dusts of the <25 μm size fractions collected on railroad ties appeared to be smaller than 10 μm, indicating that their characteristics should somewhat reflect the characteristics of airborne particles in the tunnel and the platform. As most floor dusts are magnetic, PM levels at underground Subway Stations can be controlled by removing magnetic indoor particles using magnets. In addition, airborne Subway particles, most of which were smaller than 10 μm, were collected using permanent magnets at two underground Subway Stations, namely Jegi and Yangjae Stations, in Seoul, Korea. XRD and SEM/EDX analyses showed that most of the magnetic aerosol particles collected at Jegi station was iron metal, whereas those at Yangjae station contained a small amount of Fe mixed with Na, Mg, Al, Si, S, Ca, and C. The difference in composition of the Fe-containing particles between the two Subway Stations was attributed to the different ballast tracks used.
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characterization of summertime aerosol particles collected at Subway Stations in seoul korea using low z particle electron probe x ray microanalysis
Asian journal of atmospheric environment, 2010Co-Authors: Bo Wha Kim, Jo-chun Kim, Hae Jin Jung, Young Chul Song, Mijung Lee, Hye Kyeong Kim, Jongryeul SohnAbstract:A quantitative single particle analytical technique, denoted low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA), was applied to characterize particulate matters collected at two underground Subway Stations, Jegidong and Yangje Stations, in Seoul, Korea. To clearly identify the source of the indoor aerosols in the Subway Stations, four sets of samples were collected at four different locations within the Subway Stations: in the tunnel; at the platform; near the ticket office; nearby outdoors. Aerosol samples collected on stages 2 and 3 (D p : 10- 2.5 ㎛ and 2.5-1.0 ㎛, respectively) in a 3-stage Dekati PM10 impactor were investigated. Samples were collected during summertime in 2009. The major chemical species observed in the Subway particle samples were Fe-containing, carbonaceous, and soil-derived particles, and secondary aerosols such as nitrates and sulfates. Among them, Fe-containing particles were the most popular. The tunnel samples contained 85-88% of Fe-containing particles, with the abundance of Fe-containing particles decreasing as the distances of sampling locations from the tunnel increased. The Fe-containing Subway particles were generated mainly from mechanical wear and friction processes at rail-wheel-brake interfaces. Carbonaceous, soil-derived, and secondary nitrate and/or sulfate particles observed in the underground Subway particles likely flowed in from the outdoor environment by human activities and the air-exchange between the Subway system and the outdoors. In addition, since the platform screen doors (PSDs) limit air-mixing between the tunnel and the platform, samples collected at the platform at the Yangjae station (with PSDs) showed a marked decrease in the relative abundances of Fe-containing particles compared to the Jegidong station (without PSDs).
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source identification of particulate matter collected at underground Subway Stations in seoul korea using quantitative single particle analysis
Atmospheric Environment, 2010Co-Authors: Hae Jin Jung, Jo-chun Kim, Bo Wha Kim, Ji Yeon Ryu, Shila Maskey, Jongryeul SohnAbstract:Abstract Subway particle samples collected at four underground Subway Stations in Seoul, Korea were characterized by a single-particle analytical technique, low-Z particle electron probe X-ray microanalysis. To clearly identify indoor sources of Subway particles, four sets of samples collected in tunnels, at platforms, near ticket offices, and outdoors were investigated. For the samples collected in tunnels, Fe-containing particles predominate, with relative abundances of 75–91% for the four Stations. The amounts of Fe-containing particles decrease as the distance of sampling locations from the tunnel increases. In addition, samples collected at the platform in Subway Stations with platform screen doors (PSDs) that limit air-mixing between the platform and the tunnel showed marked decreases in relative abundances of Fe-containing particles, clearly indicating that Fe-containing Subway particles are generated in the tunnel. PM10 mass concentration levels are the highest in the tunnels, becoming lower as the distance of sampling locations from the tunnel increases. The extent of the decrease in PM10 in Stations with PSDs is also larger than that in Stations without PSDs. The results clearly indicate that Fe-containing particles originating in tunnels predominate in the indoor microenvironment of Subway Stations, resulting in high indoor PM10 levels, and that PSDs play a significant role in reducing Fe-containing particles at platforms and near ticket offices.
Song Pan - One of the best experts on this subject based on the ideXlab platform.
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analysis and interpretation of the particulate matter pm10 and pm2 5 concentrations at the Subway Stations in beijing china
Sustainable Cities and Society, 2019Co-Authors: Song Pan, Jiaping Liu, Fei Pei, Xingxing Zhang, Xinru Wang, Liang Xia, Yixuan WeiAbstract:Abstract The particulate matters (PM10 and PM2.5) inside urban Subway Stations greatly influence indoor air quality and passenger comfort. This study aims to analyze and interpret the concentrations of PM10 and PM2.5, measured in several Subway Stations from October 9th to 22nd, 2016 in Beijing, China. The overall methodology was based on the Statistical Package for Social Science (SPSS) software while General linear model (GLM) and correlation analysis were further applied to examine the sensitivities of different variables to the particle concentrations. The data analysis showed the average overall mass ratio of PM concentrations inside Subway station is about 68.7%, much lower than outdoor condition (79.6%). In the areas of the station hall and platform, the real-time PM10 and PM2.5 concentrations varied periodically. In working and operation offices, all rooms had much higher PM concentrations than the outdoor environment when its pollution level was level 3, in which the facility room reached the highest level, while the closed meeting room had the lowest. Correlation analysis results indicated that PM10 and PM2.5 concentrations were mutually correlated (average R2 = 0.854), and a strong linear correlation (R2 = 0.897) of the Subway-station PM concentrations to the outdoor PM conditions, regardless of the outdoor atmospheric PM concentrations pollution level was. Nevertheless, the impact of passenger number and temperature & humidity on the station PM concentrations was less, when compared to the outdoor environment. This paper is expected to provide useful information for further research and design of effective prevention measures on PM in local Subway Stations, towards a more sustainable and healthier built environment in the city underground.
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an investigation on energy consumption of air conditioning system in beijing Subway Stations
Energy Procedia, 2017Co-Authors: Song Pan, Hongwei Wang, Fei Pei, Le Yang, Xingxing ZhangAbstract:This paper initially depicted on the energy consumption of air conditioning systems in Beijing Subway Stations. An investigation was conducted among ten underground Subway Stations to the examinati ...
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A Review of the Piston Effect in Subway Stations
Advances in Mechanical Engineering, 2013Co-Authors: Song Pan, Li Fan, Jiaping Liu, Jingchao Xie, Yuying Sun, Na Cui, Lili Zhang, Binyang ZhengAbstract:In recent years the piston effect in Subways has become a topic of interest for researchers and engineers. Many publications have appeared on this topic, but reliable information is scattered and poorly organized. This review paper covers the latest publications on the piston effect in Subways. We compile information about the mechanism of the piston effect, evaluate its influence, and describe how it can be effectively utilized.
Teresa Moreno - One of the best experts on this subject based on the ideXlab platform.
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organophosphate esters in airborne particles from Subway Stations
Science of The Total Environment, 2021Co-Authors: R Oliveroverbel, Teresa Moreno, J Fernandezarribas, Cristina Reche, Maria Cruz Minguillon, Vânia Martins, Xavier Querol, Boris Johnsonrestrepo, Ethel EljarratAbstract:Abstract For the first time, the concentrations of 19 organophosphate esters (OPEs) were measured in airborne fine particulate matter (PM2.5) from Subway Stations in Barcelona (Spain) to investigate their occurrence, contamination profiles and associated health risks. OPEs were detected in all PM2.5 samples with levels ranging between 1.59 and 202 ng/m3 (mean value of 39.9 ng/m3). Seventeen out of 19 tested analytes were detected, with TDClPP, TClPP and TCEP being those presenting the highest concentrations. OPE concentrations are not driven by the same factors that determine the ambient PM2.5 concentrations of other constituents in the Subway. Newer Stations presented higher OPE levels, probably due to the materials used in the design of the platforms, with greater use of modern plastic materials versus older Stations with tiles and stones. Estimated daily intakes via airborne particles inhalation during the time expended in Subway Stations were calculated, as well as the carcinogenic and non-carcinogenic health risks (CR and non-CR), all being much lower than the threshold risk values. Thus, Subway inhalation exposure when standing on the platform to OPE's per se is not considered to be dangerous for commuters.
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origin of polycyclic aromatic hydrocarbons and other organic pollutants in the air particles of Subway Stations in barcelona
Science of The Total Environment, 2018Co-Authors: Barend L Van Drooge, Cristina Reche, Maria Cruz Minguillon, Xavier Querol, Raimon M Prats, Joan O Grimalt, Teresa MorenoAbstract:Underground Subways transport large numbers of citizens in big cities, which must breathe air with limited ventilation. These atmospheric conditions may enhance the concentration of air pollutants from both outdoor and indoor air. The influence of ventilation conditions and maintenance activities on the concentrations of air pollutants have been studied. Particulate matter with aerodynamic diameter smaller than 2.5 μm (PM2.5) in indoor air was sampled in ten platforms of nine Subway Stations of the metropolitan area of Barcelona in 2015 and 2016. These particles were analyzed for polycyclic aromatic hydrocarbons (PAH) and organic tracer compounds. The concentrations of PAH were in the range of the street air levels with higher PAH values in the colder period. No influence of nighttime maintenance activities was observed on the platform air quality during daytime. Source apportionment analysis using the concentrations of hopanes, nicotine and levoglucosan as molecular tracer compounds showed that 75% of the detected PAH at the platforms have an outdoor PM origin. The modern Subway Stations, with advanced ventilation and platform screen doors that separate the Subway system from the platform, showed lowest PAH and PM concentrations.
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origin of inorganic and organic components of pm2 5 in Subway Stations of barcelona spain
Environmental Pollution, 2016Co-Authors: Teresa Moreno, Cristina Reche, Maria Cruz Minguillon, Vânia Martins, Barend L Van Drooge, Fulvio Amato, Eladio De Miguel, Marta Capdevila, Sonia CentellesAbstract:The present work assesses indoor air quality in Stations of the Barcelona Subway system. PM2.5 concentrations on the platforms of 4 Subway Stations were measured during two different seasons and the chemical composition was determined. A Positive Matrix Factorization analysis was performed to identify and quantify the contributions of major PM2.5 sources in the Subway Stations. Mean PM2.5 concentrations varied according to the Stations design and seasonal periods. PM2.5 was composed of haematite, carbonaceous aerosol, crustal matter, secondary inorganic compounds, trace elements, insoluble sulphate and halite. Organic compounds such as PAHs, nicotine, levoglucosan and aromatic musk compounds were also identified. Subway PM2.5 source comprised emissions from rails, wheels, catenaries, brake pads and pantographs. The Subway source showed different chemical profiles for each station, but was always dominated by Fe. Control actions on the source are important for the achievement of better air quality in the Subway environment.
