Variability of levels and composition of PM 10 and PM 2.5 in the Barcelona metro system

Abstract. From an environmental perspective, the underground metro system is one of the cleanest forms of public transportation in urban agglomerations. Current studies report contradicting results regarding air quality in the metro systems: whereas some reveal poor air quality, others report PM levels which are lower or of the same order of magnitude than those measured in traffic sites above ground level. The present work assesses summer and winter indoor air quality and passenger exposure in the Barcelona metro, focusing on PM levels and their metal contents. In addition, the impact on indoor air quality of platform screen door systems (automated systems consisting of closed rail track and platforms) is evaluated, to determine whether these systems reduce passenger exposure to PM when compared with conventional systems (open tracks and platforms). In the Barcelona metro PM levels inside the trains in summer are amongst the lowest reported for worldwide metro systems (11–32 μg m−3 PM2.5). This is most likely due to the air conditioning system working in all carriages of the Barcelona metro during the whole year. Levels were considerably higher on the platforms, reaching mean levels of 46 and 125 μg m3 in the new (L9) and old (L3) lines, respectively. PM10 data are also reported in the present study, but comparison with other metro systems is difficult due to the scarcity of data compared with PM2.5. Results showed distinct PM daily cycles, with a drastic increase from 06:00 to 07:00 a.m., a diurnal maximum from 07:00 to 10:00 p.m., and marked decrease between 10:00 p.m. and 05:00 a.m. The elements with the highest enrichment were those associated with wheel or brake abrasion products (Ba, Fe, Cu, Mn, Cr, Sb, As, Mo, Co, Sr, among others). Laminar hematite (Fe2O3) was the dominant particle type, being mainly originated by mechanical abrasion of the rail track and wheels. Regarding passenger exposure to PM, the contribution of commuting by metro was estimated to account for around 10% of the daily exposure. However, this contribution may be one order of magnitude higher when specific matals are considered. Finally, we conclude that the implementation of platform screen door systems results in reductions of both PM levels and metal concentrations. In addition an advanced optimized ventilation system gave even a much higher efficiency in reducing exposure to PM of metro commuters. Combining these two features PM exposure levels in the platforms may be reduced down by a factor of 7 with respect the old subway lines in Barcelona.

[1]  R. Rudnick,et al.  Composition of the Continental Crust , 2014 .

[2]  X. Basagaña,et al.  Personal, indoor and outdoor air pollution levels among pregnant women , 2013 .

[3]  Ki-Hyun Kim,et al.  A noticeable shift in particulate matter levels after platform screen door installation in a Korean subway station , 2012 .

[4]  V. Mugica-Álvarez,et al.  Concentrations and properties of airborne particles in the Mexico City subway system , 2012 .

[5]  Jhih-Wei Yan,et al.  Comparisons of particulate matter, CO, and CO2 levels in underground and ground-level stations in the Taipei mass rapid transit system , 2011 .

[6]  Martin L Williams,et al.  New Directions: Science and policy - Out of step on NOx and NO2? , 2011 .

[7]  C. Sioutas,et al.  Particulate matter (PM) concentrations in underground and ground-level rail systems of the Los Angeles Metro , 2011 .

[8]  Zhiwei Lian,et al.  Investigation of indoor environmental quality in Shanghai metro stations, China , 2010, Environmental monitoring and assessment.

[9]  Luc Int Panis,et al.  Exposure to particulate matter in traffic: A comparison of cyclists and car passengers , 2010 .

[10]  Eliseo Monfort,et al.  Application of Optimally Scaled Target Factor Analysis for Assessing Source Contribution of Ambient PM10 , 2009, Journal of the Air & Waste Management Association.

[11]  Mar Viana,et al.  Toward a standardised thermal-optical protocol for measuring atmospheric organic and elemental carbon: the EUSAAR protocol , 2009 .

[12]  L. Murruni,et al.  Concentrations and elemental composition of particulate matter in the Buenos Aires underground system , 2009 .

[13]  Zoltán Homonnay,et al.  Properties and sources of individual particles and some chemical species in the aerosol of a metropolitan underground railway station , 2009 .

[14]  Patrick Chazette,et al.  Link between aerosol optical, microphysical and chemical measurements in an underground railway station in Paris , 2009 .

[15]  Antonio Gasparrini,et al.  Fine particle concentrations in buses and taxis in Florence, Italy , 2008 .

[16]  Chang-Chuan Chan,et al.  Comparisons of commuter's exposure to particulate matters while using different transportation modes. , 2008, The Science of the total environment.

[17]  Yu-Hsiang Cheng,et al.  Levels of PM10 and PM2.5 in Taipei Rapid Transit System , 2008 .

[18]  Aonghus McNabola,et al.  Relative exposure to fine particulate matter and VOCs between transport microenvironments in Dublin : Personal exposure and uptake , 2008 .

[19]  Dong-Uk Park,et al.  Characteristics of PM10, PM2.5, CO2 and CO monitored in interiors and platforms of subway train in Seoul, Korea. , 2008, Environment international.

[20]  Chi Nyon Kim,et al.  Spatial distribution of particulate matter (PM10 and PM2.5) in Seoul Metropolitan Subway stations. , 2008, Journal of hazardous materials.

[21]  M. Viana,et al.  Partitioning of major and trace components in PM10–PM2.5–PM1 at an urban site in Southern Europe , 2008 .

[22]  Å. Holgersson,et al.  Mechanisms related to the genotoxicity of particles in the subway and from other sources. , 2008, Chemical research in toxicology.

[23]  R. Colvile,et al.  Levels of particulate air pollution, its elemental composition, determinants and health effects in metro systems , 2007 .

[24]  Tamás Weidinger,et al.  Time-resolved mass concentration, composition and sources of aerosol particles in a metropolitan underground railway station , 2007 .

[25]  A. Peters,et al.  Levels of outdoor PM2.5, absorbance and sulphur as surrogates for personal exposures among post-myocardial infarction patients in Barcelona, Spain , 2007 .

[26]  Mark J. Nieuwenhuijsen,et al.  Bus, minibus, metro inter-comparison of commuters' exposure to air pollution in Mexico City , 2007 .

[27]  Zhaorong Liu,et al.  IN-TRAIN AIR QUALITY ASSESSMENT OF THE RAILWAY TRANSIT SYSTEM IN BEIJING: A NOTE , 2007 .

[28]  Joseph Zayed,et al.  Manganese concentrations in the air of the Montreal (Canada) subway in relation to surface automobile traffic density. , 2006, The Science of the total environment.

[29]  A Magrini,et al.  Dust in the Underground Railway Tunnels of an Italian Town , 2006, Journal of occupational and environmental hygiene.

[30]  John D. Spengler,et al.  Steel dust in the New York City subway system as a source of manganese, chromium, and iron exposures for transit workers , 2005, Journal of Urban Health.

[31]  Martin Braniš,et al.  The contribution of ambient sources to particulate pollution in spaces and trains of the Prague underground transport system , 2006 .

[32]  Timo Mäkelä,et al.  The concentrations and composition of and exposure to fine particles (PM2.5) in the Helsinki subway system , 2005 .

[33]  A Seaton,et al.  The London Underground: dust and hazards to health , 2005, Occupational and Environmental Medicine.

[34]  Lennart Möller,et al.  Subway particles are more genotoxic than street particles and induce oxidative stress in cultured human lung cells. , 2005, Chemical research in toxicology.

[35]  Hans Moosmüller,et al.  Equivalence of elemental carbon by thermal/optical reflectance and transmittance with different temperature protocols. , 2004, Environmental science & technology.

[36]  Mark J. Nieuwenhuijsen,et al.  Commuters’ exposure to PM2.5, CO, and benzene in public transport in the metropolitan area of Mexico City , 2004 .

[37]  Sonja N Sax,et al.  Elevated airborne exposures of teenagers to manganese, chromium, and iron from steel dust and New York City's subway system. , 2004, Environmental science & technology.

[38]  S. Zou,et al.  Exposure level of carbon monoxide and respirable suspended particulate in public transportation modes while commuting in urban area of Guangzhou, China , 2002 .

[39]  Åke Sjödin,et al.  Metal emissions from road traffic and the influence of resuspension: results from two tunnel studies , 2002 .

[40]  C. Y. Chan,et al.  Commuter exposure to particulate matter in public transportation modes in Hong Kong , 2002 .

[41]  Christer Johansson,et al.  Particulate matter in the underground of Stockholm , 2002 .

[42]  Abdel Hameed A. Awad,et al.  Environmental Study in Subway Metro Stations in Cairo, Egypt , 2002 .

[43]  Yoichi Araki,et al.  SEASONAL VARIATION AND THEIR CHARACTERIZATION OF SUSPENDED PARTICULATE MATTER IN THE AIR OF SUBWAY STATIONS , 2001 .

[44]  Mark J. Nieuwenhuijsen,et al.  Fine particle (PM2.5) personal exposure levels in transport microenvironments, London, UK. , 2001, The Science of the total environment.

[45]  K. Crump,et al.  Manganese exposures in Toronto during use of the gasoline additive, methylcyclopentadienyl manganese tricarbonyl , 2000, Journal of Exposure Analysis and Environmental Epidemiology.

[46]  G Praml,et al.  Dust exposure in Munich public transportation: a comprehensive 4-year survey in buses and trams , 2000, International archives of occupational and environmental health.

[47]  Ian D. Williams,et al.  Characterisation of airborne particles in London by computer-controlled scanning electron microscopy , 1999 .

[48]  D. Raper,et al.  Commuter exposure to respirable particles inside buses and by bicycle. , 1999, The Science of the total environment.

[49]  G D Pfeifer,et al.  Personal exposures to airborne metals in London taxi drivers and office workers in 1995 and 1996. , 1999, The Science of the total environment.

[50]  H Fromme,et al.  Polycyclic aromatic hydrocarbons (PAH) and diesel engine emission (elemental carbon) inside a car and a subway train. , 1998, The Science of the total environment.

[51]  Christopher Proctor,et al.  Exposure to carbon monoxide, respirable suspended particulates and volatile organic compounds while commuting by bicycle , 1991 .

[52]  M. Morandi,et al.  A comparative study of respirable particulate microenvironmental concentrations and personal exposures , 1988, Environmental monitoring and assessment.