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

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 (10-20nm) 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. © 2014.This work was supported by the + D Project CGL2012-33066 (METRO), the Spanish Ministry of Economy and Competitiveness and FEDER funds within the I European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 315760 HEXACOMM and the IMPROVE LIFE project ( LIFE13 ENV/ES/000263 ). F. Amato is beneficiary of an AXA Research Fund postdoctoral grant. We acknowledge useful discussion with our colleague Greg Power.Peer reviewe

Conceptualizing and measuring strategy implementation – a multi-dimensional view

Through quantitative methodological approaches for studying the strategic management and planning process, analysis of data from 208 senior managers involved in strategy processes within ten UK industrial sectors provides evidence on the measurement properties of a multi-dimensional instrument that assesses ten dimensions of strategy implementation. Using exploratory factor analysis, results indicate the sub-constructs (the ten dimensions) are uni-dimensional factors with acceptable reliability and validity; whilst using three additional measures, and correlation and hierarchical regression analysis, the nomological validity for the multi-dimensional strategy implementation construct was established. Relative importance of ten strategy implementation dimensions (activities) for practicing managers is highlighted, with the mutually and combinative effects drawing conclusion that senior management involvement leads the way among the ten key identified activities vital for successful strategy implementation

Carbon dioxide, COVID-19 and the importance of restaurant ventilation: a case study from Spain approaching Christmas 2021

Restaurants present an especial challenge in the prevention of the spread of COVID-19 via exhalatory bioaerosols because customers are unprotected by facemasks while eating, so that ventilation protocols in such establishments become particularly important. However, despite the fact that this pandemic airborne disease has been with us for two full years, many restaurants are still not successfully prioritising air renovation as a key tool for reducing infection risk. We demonstrate this in the run-up to the 2021 Christmas celebrations by reporting on CO2 concentration data obtained from a hotel breakfast room and restaurants during the 5-day Spanish holiday period of 4th -8 th December. In the case of the breakfast room, inadequate ventilation resulted in average CO2 levels ranging from 868 to 1237ppm on five consecutive days, with the highest levels coinciding with highest occupancy numbers. Inside the five restaurants, three of these were well ventilated, maintaining stable average CO2 concentrations below 700ppm. In contrast, two restaurants failed to keep average CO2 levels below 1000ppm, despite sporadic, but ineffective, attempts by one of them to ventilate the establishment. More effort needs to be made to foster in both restaurant managers and the general public an improved awareness of the value of CO2 concentrations as an infection risk proxy and the relevance of ventilation issues to the propagation of respiratory diseases.IDAEA-CSIC is a Centre of Excellence Severo Ochoa (Spanish Ministry of Science and Innovation, Project CEX2018-000794-S)N

Aerosol transmission of human pathogens: From miasmata to modern viral pandemics and their preservation potential in the Anthropocene record

Ongoing uncertainty over the relative importance of aerosol transmission of COVID-19 is in part rooted in the history of medical science and our understanding of how epidemic diseases can spread through human populations. Ancient Greek medical theory held that such illnesses are transmitted by airborne pathogenic emanations containing particulate matter (“miasmata”). Notable Roman and medieval scholars such as Varro, Ibn al-Khatib and Fracastoro developed these ideas, combining them with early germ theory and the concept of contagion. A widely held but vaguely defined belief in toxic miasmatic mists as a dominant causative agent in disease propagation was overtaken by the science of 19th century microbiology and epidemiology, especially in the study of cholera, which was proven to be mainly transmitted by contaminated water. Airborne disease transmission came to be viewed as burdened by a dubious historical reputation and difficult to demonstrate convincingly. A breakthrough came with the classic mid-20th century work of Wells, Riley and Mills who proved how expiratory aerosols (their “droplet nuclei”) could transport still-infectious tuberculosis bacteria through ventilation systems. The topic of aerosol transmission of pathogenic respiratory diseases assumed a new dimension with the mid-late 20th century “Great Acceleration” of an increasingly hypermobile human population repeatedly infected by different strains of zoonotic viruses, and has taken centre stage this century in response to outbreaks of new respiratory infections that include coronaviruses. From a geoscience perspective, the consequences of pandemic-status diseases such as COVID-19, produced by viral pathogens utilising aerosols to infect a human population currently approaching 8 billion, are far-reaching and unprecedented. The obvious and sudden impacts on for example waste plastic production, water and air quality and atmospheric chemistry are accelerating human awareness of current environmental challenges. As such, the “anthropause” lockdown enforced by COVID-19 may come to be seen as a harbinger of change great enough to be preserved in the Anthropocene stratal record.We wish to thank Edward Nardell for his help and encouragement regarding the photographic record of the Wells, Riley and Mills scientific trio, and Joyce Almeida for granting permission to use the photograph of her mother June Almeida. This study was supported by the Spanish Research Council (CSIC, Project COVID-19 CSIC 202030E226) and the Generalitat de Catalunya (SGR41). IDAEA-CSIC is a Severo Ochoa Centre of Research Excellence (Spanish Ministry of Science and Innovation, Project CEX2018-000794-S).Peer reviewe

Preferential fractionation of trace metals-metalloids into PM10 resuspended from contaminated gold mine tailings at Rodalquilar, Spain

Former gold mining at Rodalquilar in southeastern Spain exploited a high sulphidation epithermal silicified ore deposit that contained significant enrichments in several metals/metalloids such as As, Sb, Bi, and Te. Treatment of this ore took place adjacent to the village and involved physical crushing then chemical extraction of gold using cyanide and zinc. The waste materials from this processing system, contaminated with a range of trace elements, were deposited immediately below the mine, and have been left exposed to erosion. Over the last 40 years these oxidised ferruginous tailings have not only polluted the local drainage system but also provided a point source for contaminated aeolian dust under the prevailing dry, windy climate. Chemical analyses of particulate matter mechanically resuspended from the tailings materials show enrichments in metals and metalloids due to the preferential incorporation of these elements into the inhalable size fraction (PM10). Of particular concern is the fact that these PM10 can contain >1,500 ppm As and >40 ppm Sb. Given that both As and Sb are clastogenic metalloids with proven negative health effects, and that their oxidised forms are especially toxic, such contamination levels in windblown dusts around old mine sites are highly undesirable