Publications by authors named "Vânia Martins"

17 Publications

  • Page 1 of 1

Screening a Targeted Panel of Genes by Next-Generation Sequencing Improves Risk Stratification in Real World Patients with Acute Myeloid Leukemia.

Cancers (Basel) 2022 Jun 30;14(13). Epub 2022 Jun 30.

Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal.

Although mutation profiling of defined genes is recommended for classification of acute myeloid leukemia (AML) patients, screening of targeted gene panels using next-generation sequencing (NGS) is not always routinely used as standard of care. The objective of this study was to prospectively assess whether extended molecular monitoring using NGS adds clinical value for risk assessment in real-world AML patients. We analyzed a cohort of 268 newly diagnosed AML patients. We compared the prognostic stratification of our study population according to the European LeukemiaNet recommendations, before and after the incorporation of the extended mutational profile information obtained by NGS. Without access to NGS data, 63 patients (23%) failed to be stratified into risk groups. After NGS data, only 27 patients (10%) failed risk stratification. Another 33 patients were re-classified as adverse-risk patients once the NGS data was incorporated. In total, access to NGS data refined risk assessment for 62 patients (23%). We further compared clinical outcomes with prognostic stratification, and observed unexpected outcomes associated with mutations. In conclusion, this study demonstrates the prognostic utility of screening AML patients for multiple gene mutations by NGS and underscores the need for further studies to refine the current risk classification criteria.
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http://dx.doi.org/10.3390/cancers14133236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9265035PMC
June 2022

Motor stereotypies in autism spectrum disorder: Clinical randomized study and classification proposal.

Autism 2022 Jun 28:13623613221105479. Epub 2022 Jun 28.

Centro Hospitalar Universitário do Porto, Portugal.

Lay Abstract: Motor stereotypies are one of the most frequent features in children with a diagnosis of autism spectrum disorder. They may disrupt children's functioning and development and be a potential source of stress for families. Several factors, including sex, age, cognitive ability, and severity of autism spectrum disorder, may influence the presence and intensity of stereotypies. The present study aimed to identify the prevalence of motor stereotypies in a group of children with autism spectrum disorder. In addition, it sought to investigate whether sex, age, cognitive ability, verbal language, neurological comorbidities, and severity of autism spectrum disorder were associated with an increased probability and higher number, duration, and variability of stereotypies. A total of 134 participants aged 2.3-17.6 years underwent a clinical protocol with standardized video-recorded sessions. Stereotypies were identified and classified by two independent evaluators. The prevalence of stereotypies was 56.7%, and a total of 1198 motor stereotypies were captured. Children who were younger, nonverbal, and had higher severity of autism spectrum disorder had an increased probability of presenting stereotypies. Being nonverbal or having higher severity of autism spectrum disorder was also associated with presenting a higher number of stereotypies. Children with developmental delay, intellectual disability, or epilepsy displayed longer stereotypies, and children with developmental delay or intellectual disability additionally presented more diverse stereotypies. As part of the study, the authors present a clinical classification model, a glossary, and video samples of motor stereotypies. The findings of this study suggest that children who are younger, nonverbal, have lower cognitive ability, and have higher severity of autism spectrum disorder may have a higher burden of stereotypies. Earlier intervention and monitoring of these children have the potential to improve their long-term outcomes.
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http://dx.doi.org/10.1177/13623613221105479DOI Listing
June 2022

Source apportionment of children daily exposure to particulate matter.

Sci Total Environ 2022 Aug 21;835:155349. Epub 2022 Apr 21.

Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), 5232, Villigen PSI, Switzerland.

The present study aims to investigate the sources of particulate pollution in indoor and outdoor environments, with focus on determining their contribution to the exposure of children to airborne particulate matter (PM). To this end, parallel indoor and outdoor measurements were carried out for a selection of 40 homes and 5 schools between September 2017 and October 2018. PM2.5 and PM2.5-10 samples were collected during five days in each microenvironment (ME) and analysed by X-Ray Fluorescence (XRF), for the determination of elements, and by a thermal-optical technique, for the measurement of organic and elemental carbon. The source apportionment analysis of the PM composition data, by means of the receptor model SoFi (Source Finder) 8 Pro, resulted in the identification of nine sources: exhaust and non-exhaust emissions from traffic, secondary particles, heavy oil combustion, industry, sea salt, soil, city dust, and an indoor source characterized by high levels of organic carbon. Integrated daily exposure to PM2.5 was on average 21 μg/m. The organic matter, resulting from cleaning, cooking, smoking and biological material, was the major source contributing by 31% to the PM2.5 exposure. The source city dust, which was highly influenced by the resuspension of dust in classrooms, was the second main source (26%), followed by traffic (24%). The major sources affecting the integrated exposure to PM10, which was on average 33 μg/m, were the city dust (39%), indoor organics (24%) and traffic (16%). This study provides important information for the design of measures to reduce the exposure of children to PM.
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http://dx.doi.org/10.1016/j.scitotenv.2022.155349DOI Listing
August 2022

HLA DQ2/DQ8 haplotypes and anti-transglutaminase antibodies as celiac disease markers in a pediatric population with type 1 diabetes mellitus.

Arch Endocrinol Metab 2022 Apr 11;66(2):229-236. Epub 2022 Apr 11.

Unidade de Endocrinologia e Diabetologia Pediátrica, Departamento de Pediatria, Hospital de Braga, Braga, Portugal.

Objective: Evaluate the celiac disease (CD) markers, within the scope of its screening, in a pediatric population with diagnosis of type 1 diabetes (T1D) at Hospital de Braga (HB) and determine the prevalence of CD in the sample. Reflect on CD screening algorithm applied in this pediatric population.

Methods: Retrospective observational study with 94 patients diagnosed with T1D at age 10 years or younger, followed up at the HB Outpatient Diabetology Consultation, including those referred from other hospitals. Record of clinical information, IgA anti-transglutaminase and anti-endomysium and HLA DQ2/DQ8 haplotypes.

Results: We obtained positive serological test for CD in 4 patients. This test had 100% sensitivity and specificity. The prevalence of CD was 4.3% (n = 4). Positive HLA screening in 84.6% of patients, with both sensitivity and negative predictive value of 100% and specificity of 16.67%. Diagnosis of CD was made on average 3.40 ± 3.32 years after the diagnosis of TD1. All cases of CD registered non-gastrointestinal manifestations, none had gastrointestinal symptoms.

Conclusion: This study proved that there is a higher prevalence of CD in pediatric population with TD1, when compared to general population, and clarified the importance of CD screening. Furthermore, it was observed that serological screening for CD antibodies is an excellent screening test and HLA typing, although not the most suitable first line test, can be useful in excluding the possibility of patients with T1D developing CD.
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http://dx.doi.org/10.20945/2359-3997000000457DOI Listing
April 2022

Adolescer Saudável: screening and follow-up of risk at school.

Einstein (Sao Paulo) 2021 22;19:eAO5849. Epub 2021 Sep 22.

Centro Hospitalar Leiria-Pombal, Leiria, Portugal.

Objective: To characterize adolescents referred to medical consultation based on the screening tool "Perfil de Saúde do Utente Adolescente", and to compare to information gathered from a questionnaire and data assessed during the visit.

Methods: A retrospective and descriptive study, with analysis of the questionnaires filled out by adolescents and their respective medical records, in the period from January 2013 to June 2016.

Results: A total of 54 adolescents were seen, 57% male and mean age of 12±1.7 years. In the questionnaire, 37% stated that they had some kind of health problem; 35% would like to change the relationship with their parents; 18% had some concern about safety at school; and 39% made dietary mistakes. Approximately 31% had consumed alcohol, 13% had tried smoking, and 4% had used other drugs. At the first medical appointment, 38% stated they had chronic disease, 11% reported poor family environment, 39% had school problems and 39% made dietary mistakes. About 13% had tried smoking, 24% had tried to consume alcohol, and 2% had tried other drugs. Thirty seven percent of adolescents were referred to adolescent medicine consultation, and 39% to another hospital consultation.

Conclusion: Many of the biopsychosocial risk items identified through the questionnaire were confirmed during consultation, indicating that it could be a useful screening method for problems linked to the adolescence period.
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http://dx.doi.org/10.31744/einstein_journal/2021AO5849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8428807PMC
October 2021

Lung-deposited dose of particulate matter from residential exposure to smoke from wood burning.

Environ Sci Pollut Res Int 2021 Dec 7;28(46):65385-65398. Epub 2021 Jul 7.

Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, 73100, Chania, Greece.

Residential settings are of utmost importance for human exposure, as it is where people spend most of their time. Residential wood combustion is a widespread practice known as a source of indoor particulate matter (PM). Nevertheless, research on the risks of exposure associated with this source is scarce, and a better understanding of respiratory deposition of smoke particles is needed. The dosimetry model ExDoM2 was applied to determine the deposited dose of inhalable particulate matter (PM) from residential biomass combustion in the human respiratory tract (HRT) of adults and children. The dose was estimated using PM exposure concentrations obtained from a field campaign carried out in two households during the operation of an open fireplace and a woodstove. Simultaneously, PM levels were monitored outside to investigate the outdoor dose in a rural area strongly impacted by biomass burning emissions. Indoors, the 8-h average PM concentrations ranged from 88.3 to 489 μg m and from 69.4 to 122 μg m for the operation of the fireplace and the woodstove, respectively, while outdoor average PM concentrations ranged from 17.3 to 94.2 μg m. The highest amount of the deposited particles was recorded in the extrathoracic region (68-79%), whereas the deposition was much lower in the tracheobronchial tree (5-6%) and alveolar-interstitial region (16-21%). The total dose received while using the fireplace was more than twofold the one received in the room with a woodstove and more than 10 times higher than in the absence of the source. Overall, indoor doses were higher than the ones received by a subject exposed outdoors, especially at the alveolar-interstitial region. After 24 h of exposure, it was estimated that approximately 35 to 37% of the particles deposited in the HRT were transferred to the gastrointestinal tract, while approximately 2.0-2.5% were absorbed into the blood. The results from exposure and dose of indoor particles gathered in this work suggest that homeowners should be encouraged to upgrade the wood burning technology to reduce the PM levels inside their residences. This study also provides biologically relevant results on the lung deposition of particles from residential biomass burning that can be used as a reference for future research.
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http://dx.doi.org/10.1007/s11356-021-15215-4DOI Listing
December 2021

Analysis of spatial factors, time-activity and infiltration on outdoor generated PM exposures of school children in five European cities.

Sci Total Environ 2021 Sep 16;785:147111. Epub 2021 Apr 16.

Department of Public Health Solutions, Finnish Institute for Health and Welfare (THL), 70701 Kuopio, Finland.

Atmospheric particles are a major environmental health risk. Assessments of air pollution related health burden are often based on outdoor concentrations estimated at residential locations, ignoring spatial mobility, time-activity patterns, and indoor exposures. The aim of this work is to quantify impacts of these factors on outdoor-originated fine particle exposures of school children. We apply nested WRF-CAMx modelling of PM concentrations, gridded population, and school location data. Infiltration and enrichment factors were collected and applied to Athens, Kuopio, Lisbon, Porto, and Treviso. Exposures of school children were calculated for residential and school outdoor and indoor, other indoor, and traffic microenvironments. Combined with time-activity patterns six exposure models were created. Model complexity was increased incrementally starting from residential and school outdoor exposures. Even though levels in traffic and outdoors were considerably higher, 80-84% of the exposure to outdoor particles occurred in indoor environments. The simplest and also commonly used approach of using residential outdoor concentrations as population exposure descriptor (model 1), led on average to 26% higher estimates (15.7 μg/m) compared with the most complex model (# 6) including home and school outdoor and indoor, other indoor and traffic microenvironments (12.5 μg/m). These results emphasize the importance of including spatial mobility, time-activity and infiltration to reduce bias in exposure estimates.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147111DOI Listing
September 2021

Agenesis of the septum pellucidum.

BMJ Case Rep 2021 Mar 5;14(3). Epub 2021 Mar 5.

Department of Neonatology A, Maternidade Dr Daniel de Matos, Centro Hospitalar e Universitario de Coimbra EPE, Coimbra, Portugal.

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http://dx.doi.org/10.1136/bcr-2020-240716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7939009PMC
March 2021

Chemical characterisation of particulate matter in urban transport modes.

J Environ Sci (China) 2021 Feb 23;100:51-61. Epub 2020 Jul 23.

Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Lisbon, Portugal.

Traffic is a main source of air pollutants in urban areas and consequently daily peak exposures tend to occur during commuting. Personal exposure to particulate matter (PM) was monitored while cycling and travelling by bus, car and metro along an assigned route in Lisbon (Portugal), focusing on PM2.5 and PM10 (PM with aerodynamic diameter <2.5 and 10 µm, respectively) mass concentrations and their chemical composition. In vehicles, the indoor-outdoor interplay was also evaluated. The PM2.5 mean concentrations were 28 ± 5, 31 ± 9, 34 ± 9 and 38 ± 21 µg/m for bus, bicycle, car and metro modes, respectively. Black carbon concentrations when travelling by car were 1.4 to 2.0 times higher than in the other transport modes due to the closer proximity to exhaust emissions. There are marked differences in PM chemical composition depending on transport mode. In particular, Fe was the most abundant component of metro PM, derived from abrasion of rail-wheel-brake interfaces. Enhanced concentrations of Zn and Cu in cars and buses were related with brake and tyre wear particles, which can penetrate into the vehicles. In the motorised transport modes, Fe, Zn, Cu, Ni and K were correlated, evidencing their common traffic-related source. On average, the highest inhaled dose of PM2.5 was observed while cycling (55 µg), and the lowest in car travels (17 µg). Cyclists inhaled higher doses of PM2.5 due to both higher inhalation rates and longer journey times, with a clear enrichment in mineral elements. The presented results evidence the importance of considering the transport mode in exposure assessment studies.
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http://dx.doi.org/10.1016/j.jes.2020.07.008DOI Listing
February 2021

Relationship between indoor and outdoor size-fractionated particulate matter in urban microenvironments: Levels, chemical composition and sources.

Environ Res 2020 04 1;183:109203. Epub 2020 Feb 1.

Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Lisbon, Portugal.

Exposure to particulate matter (PM) has been associated with adverse health outcomes, particularly in susceptible population groups such as children. This study aims to characterise children's exposure to PM and its chemical constituents. Size-segregated aerosol samples (PM0.25, PM0.25-0.5, PM0.5-1.0, PM1.0-2.5 and PM2.5-10) were collected in the indoor and outdoor of homes and schools located in Lisbon (Portugal). Organic and elemental carbon (OC and EC) were determined by a thermo-optical method, whereas major and trace elements were analysed by X-Ray Fluorescence. In school, the children were exposed to higher PM concentrations than in home, which might be associated not only to the elevated human occupancy but also to outdoor infiltration. The pattern of PM mass size distribution was dependent on the location (home vs. school and indoor vs. outdoor). The presence of EC in PM0.25 and OC in PM0.25-0.5 was linked to traffic exhaust emissions. OC and EC in PM2.5-10 may be explained by their adhesion to the surface of coarser particles. Generally, the concentrations of mineral and marine elements increased with increasing PM size, while for anthropogenic elements happened the opposite. In schools, the concentrations of mineral matter, anthropogenic elements and marine aerosol were higher than in homes. High mineral matter concentrations found in schools were related to the close proximity to busy roads and elevated human occupancy. Overall, the results suggest that exposure to PM is relevant and highlights the need for strategies that provide healthier indoor environments, principally in schools.
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http://dx.doi.org/10.1016/j.envres.2020.109203DOI Listing
April 2020

Mediterranean Spotted Fever in Children: Study of a Portuguese Endemic Region.

Acta Med Port 2018 Apr 30;31(4):196-200. Epub 2018 Apr 30.

Pediatric Department. Centro Hospitalar de Trás-os-Montes e Alto Douro. Vila Real, Portugal.

Introduction: Mediterranean spotted fever is an infectious disease included in the human rickettsiosis group, with its main distribution in the Mediterranean and South European countries. It is an endemic disease in Portugal, with dogs acting as the main domestic reservoir. Children are a particularly vulnerable group due to their close contact with household animals and by frequently playing outdoors. In this study, we aim to describe the local epidemiology and characterize the clinical features and treatment options in a Portuguese endemic region.

Materials And Methods: We performed a prospective descriptive study of the Mediterranean spotted fever cases admitted to the paediatrics emergency department of a of a group II hospital, between January 1st 2013 and December 31st 2015. All patients were examined by a physician, who was later asked to fill out a detailed questionnaire regarding clinical presentation, diagnostic attitudes and treatment of their patients. Parents were later interviewed and questioned about post-discharge disease evolution.

Results: We registered 32 cases (93.9% reported between July and October). After fever, the most frequent reported symptoms were myalgia (37.5%), abdominal pain (25%) and headache (25%). Exanthema was present in 84.4% of cases by the third day of fever:maculonodular (53.1%), papular (37.5%) and macular (9.4%). Eschars were found in 59% of patients, with regional lymphadenopathypresent in 46.9% of cases. Azithromycin (84.4%) and doxycycline (15.5%) were the selected treatments in our population, with no cases of therapeutic failure or side-effects reported.

Conclusion: The incidence of Mediterranean spotted fever is higher in our population in comparison with the rest of the country. Fever, myalgia, abdominal pain and headache were the most common presenting symptoms, while exanthema was the predominant cutaneous finding. Azithromycin was the preferred treatment and it proved to be successful and safe in all cases.
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http://dx.doi.org/10.20344/amp.9713DOI Listing
April 2018

Identification of technical problems affecting performance of DustTrak DRX aerosol monitors.

Sci Total Environ 2017 Apr 30;584-585:849-855. Epub 2017 Jan 30.

Institute for Environmental Assessment and Water Research (IDÆA-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain.

The TSI DustTrak Aerosol Monitor is a portable real-time instrument widely used for particulate matter (PM) mass concentrations monitoring. The aim of this work is to report on issues that have arisen from the use of the latest generation models DustTrak DRX (8533 and 8534) in the BREATHE, UPTECH and IMPROVE projects that can compromise data quality. The main issue we encountered was the occurrence of sudden artefact jumps in PM concentration, which can involve an increase from a few to some hundreds of μg·m. These artefact jumps can sometimes be easily recognised ("obvious jump"), while others can be difficult to identify because the difference in the concentrations before and after the jump might be just few μg·m ("possible jump") or because the jump is sustained over the whole monitoring period and only detectable if PM concentrations are simultaneously measured by other instruments ("hidden jump"). Moreover, in areas of relatively low PM levels, the unit reported concentration of 0μg·m for ambient PM concentration or even negative concentration values which may seriously compromise the dataset. These data suggest issues with the detection of low PM concentrations, which could be due to an incorrect instrument offset or the factory calibration setting being inadequate for these PM concentrations. The upward and downward artefact jumps were not related to especially dusty or clean conditions, since they have been observed in many kinds of environments: indoor and outdoor school environments, subway stations and in ambient urban background air. Therefore, PM concentration data obtained with the TSI DustTrak DRX models should be handled with care and meticulously revised before being considered valid. To prevent these issues the use of auto zero module is recommended, so the DustTrak monitor is automatic re-zeroed without requiring the presence of any user.
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http://dx.doi.org/10.1016/j.scitotenv.2017.01.129DOI Listing
April 2017

Factors controlling air quality in different European subway systems.

Environ Res 2016 Apr 22;146:35-46. Epub 2015 Dec 22.

Institute of Environmental Assessment and Water Research (IDAEA), CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain.

Sampling campaigns using the same equipment and methodology were conducted to assess and compare the air quality at three South European subway systems (Barcelona, Athens and Oporto), focusing on concentrations and chemical composition of PM2.5 on subway platforms, as well as PM2.5 concentrations inside trains. Experimental results showed that the mean PM2.5 concentrations widely varied among the European subway systems, and even among different platforms within the same underground system, which might be associated to distinct station and tunnel designs and ventilation systems. In all cases PM2.5 concentrations on the platforms were higher than those in the urban ambient air, evidencing that there is generation of PM2.5 associated with the subway systems operation. Subway PM2.5 consisted of elemental iron, total carbon, crustal matter, secondary inorganic compounds, insoluble sulphate, halite and trace elements. Of all metals, Fe was the most abundant, accounting for 29-43% of the total PM2.5 mass (41-61% if Fe2O3 is considered), indicating the existence of an Fe source in the subway system, which could have its origin in mechanical friction and wear processes between rails, wheels and brakes. The trace elements with the highest enrichment in the subway PM2.5 were Ba, Cu, Mn, Zn, Cr, Sb, Sr, Ni, Sn, Co, Zr and Mo. Similar PM2.5 diurnal trends were observed on platforms from different subway systems, with higher concentrations during subway operating hours than during the transport service interruption, and lower levels on weekends than on weekdays. PM2.5 concentrations depended largely on the operation and frequency of the trains and the ventilation system, and were lower inside the trains, when air conditioning system was operating properly, than on the platforms. However, the PM2.5 concentrations increased considerably when the train windows were open. The PM2.5 levels inside the trains decreased with the trains passage in aboveground sections.
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http://dx.doi.org/10.1016/j.envres.2015.12.007DOI Listing
April 2016

Urban air quality comparison for bus, tram, subway and pedestrian commutes in Barcelona.

Environ Res 2015 Oct 13;142:495-510. Epub 2015 Aug 13.

WPS, C/Major 13, 08870 Sitges, Spain.

Access to detailed comparisons in air quality variations encountered when commuting through a city offers the urban traveller more informed choice on how to minimise personal exposure to inhalable pollutants. In this study we report on an experiment designed to compare atmospheric contaminants inhaled during bus, subway train, tram and walking journeys through the city of Barcelona. Average number concentrations of particles 10-300 nm in size, N, are lowest in the commute using subway trains (N<2.5×10(4) part. cm(-3)), higher during tram travel and suburban walking (2.5×10(4) cm(-3)5.0×10(4) cm(-3)), with extreme transient peaks at busy traffic crossings commonly exceeding 1.0×10(5) cm(-3) and accompanied by peaks in Black Carbon and CO. Subway particles are coarser (mode 90 nm) than in buses, trams or outdoors (<70 nm), and concentrations of fine particulate matter (PM2.5) and Black Carbon are lower in the tram when compared to both bus and subway. CO2 levels in public transport reflect passenger numbers, more than tripling from outdoor levels to >1200 ppm in crowded buses and trains. There are also striking differences in inhalable particle chemistry depending on the route chosen, ranging from aluminosiliceous at roadsides and near pavement works, ferruginous with enhanced Mn, Co, Zn, Sr and Ba in the subway environment, and higher levels of Sb and Cu inside the bus. We graphically display such chemical variations using a ternary diagram to emphasise how "air quality" in the city involves a consideration of both physical and chemical parameters, and is not simply a question of measuring particle number or mass.
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http://dx.doi.org/10.1016/j.envres.2015.07.022DOI Listing
October 2015

Origin of inorganic and organic components of PM2.5 in subway stations of Barcelona, Spain.

Environ Pollut 2016 Jan 16;208(Pt A):125-136. Epub 2015 Jul 16.

Institute of Environmental Assessment and Water Research (IDAEA), CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain.

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.
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http://dx.doi.org/10.1016/j.envpol.2015.07.004DOI Listing
January 2016

Exposure to airborne particulate matter in the subway system.

Sci Total Environ 2015 Apr 21;511:711-22. Epub 2015 Jan 21.

Institute of Environmental Assessment and Water Research (IDAEA), CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain.

The Barcelona subway system comprises eight subway lines, at different depths, with different tunnel dimensions, station designs and train frequencies. An extensive measurement campaign was performed in this subway system in order to characterise the airborne particulate matter (PM) measuring its concentration and investigating its variability, both inside trains and on platforms, in two different seasonal periods (warmer and colder), to better understand the main factors controlling it, and therefore the way to improve air quality. The majority of PM in the underground stations is generated within the subway system, due to abrasion and wear of rail tracks, wheels and braking pads caused during the motion of the trains. Substantial variation in average PM concentrations between underground stations was observed, which might be associated to different ventilation and air conditioning systems, characteristics/design of each station and variations in the train frequency. Average PM2.5 concentrations on the platforms in the subway operating hours ranged from 20 to 51 and from 41 to 91 μg m(-3) in the warmer and colder period, respectively, mainly related to the seasonal changes in the subway ventilation systems. The new subway lines with platform screen doors showed PM2.5 concentrations lower than those in the conventional system, which is probably attributable not only to the more advanced ventilation setup, but also to the lower train frequency and the design of the stations. PM concentrations inside the trains were generally lower than those on the platforms, which is attributable to the air conditioning systems operating inside the trains, which are equipped with air filters. This study allows the analysis and quantification of the impact of different ventilation settings on air quality, which provides an improvement on the knowledge for the general understanding and good management of air quality in the subway system.
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http://dx.doi.org/10.1016/j.scitotenv.2014.12.013DOI Listing
April 2015

A new look at inhalable metalliferous airborne particles on rail subway platforms.

Sci Total Environ 2015 Feb 18;505:367-75. Epub 2014 Oct 18.

WPS, C/Major 13, 08870 Sitges, Spain.

Most particles breathed on rail subway platforms are highly ferruginous (FePM) and extremely small (nanometric to a few microns in size). High magnification observations of particle texture and chemistry on airborne PM₁₀ samples collected from the Barcelona Metro, combined with published experimental work on particle generation by frictional sliding, allow us to propose a general model to explain the origin of most subway FePM. Particle generation occurs by mechanical wear at the brake-wheel and wheel-rail interfaces, where magnetic metallic flakes and splinters are released and undergo progressive atmospheric oxidation from metallic iron to magnetite and maghemite. Flakes of magnetite typically comprise mottled mosaics of octahedral nanocrystals (10-20 nm) that become pseudomorphed by maghemite. Continued oxidation results in extensive alteration of the magnetic nanostructure to more rounded aggregates of non-magnetic hematite nanocrystals, with magnetic precursors (including iron metal) still preserved in some particle cores. Particles derived from steel wheel and rails contain a characteristic trace element chemistry, typically with Mn/Fe=0.01. Flakes released from brakes are chemically very distinctive, depending on the pad composition, being always carbonaceous, commonly barium-rich, and texturally inhomogeneous, with trace elements present in nanominerals incorporated within the crystalline structure. In the studied subway lines of Barcelona at least there appears to be only a minimal aerosol contribution from high temperature processes such as sparking. To date there is no strong evidence that these chemically and texturally complex inhalable metallic materials are any more or less toxic than street-level urban particles, and as with outdoor air, the priority in subway air quality should be to reduce high mass concentrations of aerosol present in some stations.
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http://dx.doi.org/10.1016/j.scitotenv.2014.10.013DOI Listing
February 2015
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