Oxidative potential of particles in different occupational environments: a pilot study

The oxidative potential (OP) of particulate matter has been proposed as a toxicologically relevant metric. This concept is already frequently used for hazard characterization of ambient particles but it is still seldom applied in the occupational field. The objective of this study was to assess the OP in two different types of workplaces and to investigate the relationship between the OP and the physicochemical characteristics of the collected particles. At a toll station, at the entrance of a tunnel ('Tunnel' site), and at three different mechanical yards ('Depot' sites), we assessed particle mass (PM4 and PM2.5 and size distribution), number and surface area, organic and elemental carbon, polycyclic aromatic hydrocarbon (PAH), and four quinones as well as iron and copper concentration. The OP was determined directly on filters without extraction by using the dithiothreitol assay (DTT assay-OP(DTT)). The averaged mass concentration of respirable particles (PM4) at the Tunnel site was about twice the one at the Depot sites (173±103 and 90±36 µg m(-3), respectively), whereas the OP(DTT) was practically identical for all the sites (10.6±7.2 pmol DTT min(-1) μg(-1) at the Tunnel site; 10.4±4.6 pmol DTT min(-1) μg(-1) at the Depot sites). The OP(DTT) of PM4 was mostly present on the smallest PM2.5 fraction (OP(DTT) PM2.5: 10.2±8.1 pmol DTT min(-1) μg(-1); OP(DTT) PM4: 10.5±5.8 pmol DTT min(-1) μg(-1) for all sites), suggesting the presence of redox inactive components in the PM2.5-4 fraction. Although the reactivity was similar at the Tunnel and Depot sites irrespective of the metric chosen (OP(DTT) µg(-1) or OP(DTT) m(-3)), the chemicals associated with OP(DTT) were different between the two types of workplaces. The organic carbon, quinones, and/or metal content (Fe, Cu) were strongly associated with the DTT reactivity at the Tunnel site whereas only Fe and PAH were associated (positively and negatively, respectively) with this reactivity at the Depot sites. These results demonstrate the feasibility of measuring of the OP(DTT) in occupational environments and suggest that the particulate OP(DTT) is integrative of different physicochemical properties. This parameter could be a potentially useful exposure proxy for investigating particle exposure-related oxidative stress and its consequences. Further research is needed mostly to demonstrate the association of OP(DTT) with relevant oxidative endpoints in humans exposed to particles.

Running mechanical alterations during repeated treadmill sprints in hot versus hypoxic environments : a pilot study.

We determined if performance and mechanical running alterations during repeated treadmill sprinting differ between severely hot and hypoxic environments. Six male recreational sportsmen (team- and racket-sport background) performed five 5-s sprints with 25-s recovery on an instrumented treadmill, allowing the continuous (step-by-step) measurement of running kinetics/kinematics and spring-mass characteristics. These were randomly conducted in control (CON; 25°C/45% RH, inspired fraction of oxygen = 20.9%), hot (HOT; 38°C/21% RH, inspired fraction of oxygen = 20.9%; end-exercise core temperature: ~38.6°C) and normobaric hypoxic (HYP, 25°C/45% RH, inspired fraction of oxygen = 13.3%/simulated altitude of ~3600 m; end-exercise pulse oxygen saturation: ~84%) environments. Running distance was lower (P < 0.05) in HOT compared to CON and HYP for the first sprint but larger (P < 0.05) sprint decrement score occurred in HYP versus HOT and CON. Compared to CON, the cumulated distance covered over the five sprints was lower (P < 0.01) in HYP but not in HOT. Irrespective of the environmental condition, significant changes occurred from the first to the fifth sprint repetitions (all three conditions compounded) in selected running kinetics (mean horizontal forces, P < 0.01) or kinematics (contact and swing times, both P < 0.001; step frequency, P < 0.001) and spring-mass characteristics (vertical stiffness, P < 0.001; leg stiffness, P < 0.01). No significant interaction between sprint number and condition was found for any mechanical data. Preliminary evidence indicates that repeated-sprint ability is more impaired in hypoxia than in a hot environment, when compared to a control condition. However, as sprints are repeated, mechanical alterations appear not to be exacerbated in severe (heat, hypoxia) environmental conditions.

Urban environments and situated institutions : everyday governance in west Bengal

How do processes of power shape the urban environment in small Indian cities? On a day-to-day basis, who actually controls access to and the use of environmental resources? How is this done? Answering these questions contributes to our ability to develop a nuanced understanding the urban condition. In order to investigate these questions an actor-oriented approach is developed, drawing on the anthropological literatures on everyday governance and the everyday state. This conceptual framework informs an urban political ecology approach oriented towards everyday practices and the micro-politics of the (re)production of urban socio-natures. This thesis employs a mixed methods approach to qualitative research. Three cases are presented to explore: para (neighbourhood) clubs as governance actors, the governance of the urban pondscape, and the urban political ecology of solid waste management. These case studies serve to highlight how power shapes the (re)production of urban socio-natures through the everyday environmental governance practices of a complex network of governance actors. This work further demonstrates how multiple intersectionalities, including class, caste and access to political and social authority, shape these practices and their outcomes. Finally, the manner in which balances of power, place making and the formation of subject positions may both result from and shape everyday environmental governance practices and their outcomes is explored. This empirical investigation makes a number of contributions to the literature. It has explores the hereto-understudied topics of environmental governance in small cities in India, the urban political ecologies of non-piped water and of solid waste, and the role of clubs as governance actors. It further contributes to conversations within the literature on how to deepen and broaden Urban Political Ecology by engaging with everyday practices, and cases of ordinary, not-openly contested socio-natures. -- Comment les processus de pouvoir influencent-ils l'environnement urbain dans les petites villes indiennes ? Au quotidien, qui contrôle l'accès et l'utilisation des ressources environnementales ? Comment ce contrôle s'exerce-t-il ? Répondre à ces questions contribue au développement d'une compréhension nuancée de la condition urbaine. Afin d'explorer ces questions une approche actor-oriented de la gouvernance quotidienne est développée, faisant appel aux littératures anthropologiques de la gouvernance quotidienne et de l'everyday state. Ce cadre conceptuel établit ainsi une approche d'Urban Political Ecology orientée vers les pratiques quotidiennes et la micro- politique de la (re) production des socio-natures urbaines. Cette thèse emploie des méthodes qualitatives mixtes. Trois cas sont présentés afin d'étudier : les clubs para (quartier) comme acteurs de la gouvernance; la gouvernance de la pondscape urbaine; et l'urban political ecology de la gestion des déchets solides. Ces études de cas permettent de mettre en lumière la façon dont le pouvoir influence la (re)production des socio-natures urbaines par le biais des pratiques quotidiennes de gouvernance environnementale d'un réseau complexe d'acteurs. Ce travail démontre également comment plusieurs intersectionnalités, y compris la classe, la caste et l'accès au pouvoir politique et social, façonnent ces pratiques de gouvernance et leurs produits. Finalement, cette recherche explore la manière dont les équilibres de pouvoir, la fabrication de lieux et la formation de la position du sujet peuvent à la fois résulter de et contribuer à façonner les pratiques quotidiennes de gouvernance environnementale et leurs produits. Cette investigation empirique fait ainsi plusieurs contributions à la littérature. Elle explore les questions jusque-là sous-étudiées de la gouvernance environnementale dans les petites villes en Inde, de l'urban political ecology de l'eau non courante et des déchets solides, ainsi que du rôle des clubs comme acteurs de la gouvernance. Celle-ci contribue également à des débats sur la façon d'approfondir et d'élargir l'urban political ecology en travaillant sur les pratiques quotidiennes, et sur des cas de socio-natures ordinaires, pas ouvertement contestées.