Significant Reduction of Antibiotic Use in the Community after a Nationwide Campaign in France, 2002–2007

Didier Guillemot and colleagues describe the evaluation of a nationwide programme in France aimed at decreasing unnecessary outpatient prescriptions for antibiotics. The campaign was successful, particularly in reducing prescriptions for children

Strong constraints on aerosol-cloud interactions from volcanic eruptions.

Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. Here we show that the massive 2014-2015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud droplets-consistent with expectations-but had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around -0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response

No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally

Martian dust storm impact on atmospheric H₂O and D/H observed by ExoMars Trace Gas Orbiter

Global dust storms on Mars are rare but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes, as well as a decrease in the water column at low latitudes. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere

Remote sensing of atmospheric boundary layer composition using infrared satellite observations

Measuring the composition of the planetary boundary layer is essential for monitoring pollutants and for understanding their impact on environment and health. Nadir satellite remote sensing is particularly appealing to sound this part of the atmosphere, but is however challenging because pollutants concentrations are generally weak and confined in a small part of the atmospheric column. Among the sounders currently in orbit, those operating in the thermal infrared have usually their maximum sensitivity in the mid-troposphere, and are thought to be inadequate to measure the near-surface atmospheric composition. Their sensitivity to this part of the atmosphere is indeed generally limited by low temperature contrast (called thermal contrast) between the ground and the air above it. Shortly before the beginning of this PhD, this has however been challenged with different studies, which have shown the possibility to measure air pollution with thermal infrared sounders in case of high thermal contrast conditions. This was especially demonstrated with the measurement of ammonia global distribution using the Infrared Atmospheric Sounding Interferometer (IASI). This work aims at fully exploring the capabilities of thermal infrared sounders to sound the near-surface atmospheric composition. It mainly focuses on the observations of the IASI instrument, and addresses the following questions: where and when is IASI sensitive to the near-surface atmosphere? How large and how variable is the sensitivity to near-surface pollutants? What are the parameters that drive this variability? The answers to these questions are looked at for two pollutants: sulphur dioxide (SO2) and carbon monoxide (CO), and are obtained through a series of different analyses. SO2 is the first constituent on which this work focuses. The retrieval of its near-surface concentration is first of all attempted in an area surrounding the industrial area of Norilsk. This region, well-known for the extraction of heavy metals and its extremely high levels of pollution, encounters large temperature inversions in winter, which trap SO2 close to the ground. By exploiting these (corresponding to high negative thermal contrast), we show that it is possible to retrieve the surface SO2 concentrations in the region. This is done using a simplified version of the optimal estimation method, based on the use of a total measurement error covariance matrix. Further, we show that the surface SO2 concentration retrieval using the ν3 band is limited, in addition to thermal contrast, by the strong water (H2O) absorption, which renders the lowest atmosphere opaque in this spectral range in case of large humidity. Two conditions are therefore shown to be required to monitor near-surface SO2 in the ν3 band: large thermal contrast and low surface humidity. These findings are confirmed with the retrieval of SO2 at global scale, performed using a newly developed retrieval scheme based on the conversion of radiance indexes into SO2 columns using look-up-tables. It is composed of two successive steps: 1) the determination of the altitude of SO2 and the selection of low plumes (below 4 km), 2) for the selected observations, the conversion of radiance indexes into integrated SO2 0–4 km columns. The distributions and time series so obtained are used to better characterise the variability of IASI sensitivity to surface SO2 in the ν3 band at the global scale, and more particularly, in terms of thermal contrast strength and total column of H2O.The characterisation of IASI sensitivity to CO is realised in a second part of the work. Radiative transfer simulations are conducted first to determine the possibility to detect enhancement in CO near-surface concentrations with IASI. The framework of the optimal estimation is then used to investigate the capability of IASI to decorrelate, as a function of thermal contrast, the CO concentration in the low troposphere from that in the high troposphere. Finally, comparisons of IASI CO observations with co-located aircraft and ground-based measurements are shown to confirm with real data how IASI sensitivity to near-surface CO varies in terms of thermal contrast conditions, and to which extent it allows determining the CO abundance in case of high pollution.Mesurer la composition de la couche limite atmosphérique depuis les satellites est essentiel pour comprendre l’impact des polluants sur l’environnement global et sur la santé. Parmi les sondeurs actuellement en orbite, ceux opérant dans l’infrarouge thermique sont souvent considérés comme inadéquats pour cet objectif, leur sensibilité à l’atmosphère de surface étant généralement limitée par de faibles contrastes de température (appelés contrastes thermiques, TC) entre le sol et l’air au-dessus. Différentes études récentes ont cependant montré la possibilité de mesurer la pollution de l’air avec ce type de sondeur dans des conditions de TC élevé.Ce travail a pour objectif de redéfinir la capacité des sondeurs opérant dans l’infrarouge thermique à mesurer la composition de l’atmosphère de surface. Il se focalise sur les observations de l’instrument IASI (Interféromètre Atmosphérique de Sondage Infrarouge), et tente de répondre, pour les deux polluants que sont le dioxyde de soufre (SO2) et le monoxyde de carbone (CO), aux questions suivantes :Où et quand IASI est-il sensible à l’atmosphère de surface ?Quels sont les paramètres qui influencent cette sensibilité et dans quelle mesure?Dans une première partie, la thèse se focalise sur l’ajustement des concentrations de SO2 de surface pour la région industrielle de Norilsk, connue pour son niveau de pollution élevé. Nous montrons qu’il y est possible de restituer les concentrations de surface de SO2 en hiver, en exploitant les larges inversions de température (TC négatifs) qui s’y développent. Les restitutions reposent sur une version simplifiée de la méthode de l’estimation optimale, utilisant une matrice complète de l’erreur de mesure. En plus du TC, nous montrons que l’ajustement dans la bande ν3 du SO2 est également limité par la forte absorption de la vapeur d’eau (H2O), qui rend les basses couches de l’atmosphère opaques. La nécessité de combiner des TCs élevés et une faible humidité pour permettre la mesure du SO2 en surface est confirmée par une analyse à l’échelle globale, utilisant une méthode basée sur la mesure d’indices de radiance et leur conversion en colonnes de SO2 à l’aide de tables pré-calculées. Composée de 2 étapes, cette méthode identifie et sélectionne d’abord les panaches situés sous 4 km ;elle convertit ensuite les indices de radiance en colonnes de SO2 intégrées entre 0 et 4 km. Les distributions et séries temporelles obtenues sont utilisées pour caractériser, en termes de valeurs de TC et de colonnes totales d’H2O, la variabilité de la sensibilité de IASI au SO2 de surface dans la bande ν3.Dans la seconde partie du travail, des simulations de transfert radiatif sont entreprises pour déterminer la possibilité de détecter avec IASI des augmentations de la concentration de CO dans l’atmosphère de surface. Le formalisme de l’estimation optimale est aussi utilisé pour analyser l’influence du TC sur la capacité de IASI à décorreler les concentrations du CO dans la basse et la haute troposphère. Finalement, des comparaisons entre les concentrations de CO restituées des mesures IASI sous différentes conditions de TC et de pollution et celles mesurées par avions et par des stations au sol complètent la caractérisation.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

La mise sur le marché des médicaments à usage humain et la responsabilité civile des entreprises pharmaceutiques : quelle place pour le principe de précaution ?

Master [120] en droit, Université catholique de Louvain, 201

Imagerie par résonance magnétique dans le bilan des lombalgies et lombo-radiculalgies (indications et résultats)

LILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Measuring air pollution from thermal infrared satellite observations:when, where and how?

International audienceAir quality has become a major concern in many megacities and highly populated areas. In thoseregions, there is a need to properly quantify the emissions of pollutants and to understand theirtransport pathways and their reactivity in the atmosphere. In recent years, there has been importantprogress in the monitoring of air quality from satellites. Among the instruments currently in orbit,those operating in the thermal infrared have usually their maximum sensitivity in the midtroposphereand were thought to be inadequate for probing the near-surface atmosphericcomposition. This has, however, been challenged recently with IASI measurements of surface airpollution in specific geophysical conditions, characterized in particular by large temperaturedifferences between the ground and the air above it.This work will review the principal results obtained with IASI on the sounding of the near-surfaceatmospheric composition, especially above pollution hotspots. The presentation will then address thefollowing questions: where and when is IASI sensitive to the near-surface atmosphere? How largeand how variable is the sensitivity to near-surface pollutants? Which are the parameters that drivethis variability? Answers to these questions will be given for sulfur dioxide (SO2) and carbonmonoxide (CO) on the basis of theoretical sensitivity studies (radiative transfer simulations andretrieval diagnostics) and real test cases. Based on the results, the capability of IASI to monitor airquality will be revisited

Surveillance de la pollution de l’air par les observations spatiales infrarouges de l’instrument IASI

Invited talkinfo:eu-repo/semantics/nonPublishe

Retrieval of near-surface sulfur dioxide (SO2) concentrations at a global scale using IASI satellite observations

International audienceSulfur dioxide (SO2) is an atmospheric trace gas with both natural and anthropogenic sources. In the troposphere, SO2 released by industrial activities mainly stays close to the ground level. The IASI/MetOp infrared remote sensor has shown over the years good performances for tracking SO2 plumes in the free troposphere. Probing anthropogenic SO2 pollution on the other hand is a challenge due to the generally low sensitivity of infrared measurements to the near-surface atmosphere, itself caused by the weak thermal contrasts between the ground and the air above it. Recent studies, which have focused on local sources (the industrial area of Norilsk and of the North China Plain), have however demonstrated that IASI was able to retrieve SO2 near-surface concentrations in favorable meteorological situations, and in particular in case of large temperature inversions. Expanding on these findings, this work presents new observations of near-surface SO2 at global scale from IASI observations. The method, which includes the determination of the SO2 plume altitude and SO2 boundary layer column, will be briefly presented. Global distributions of anthropogenic pollution will be shown, focusing on the identification of the principal hotspots and of exceptional pollution events. A first assessment of the retrieved columns with correlative measurements will be provided for some local sources. IASI measurements and new OMI SO2 retrievals will be compared. This will highlight the complementarity of these current TIR and UV sounders for measuring SO2 pollution, which could be exploited in the future with IASI-NG and Sentinel-5 instruments