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Atmospheric aerosol impact on climate is one of the most uncertain aspects of the climate change. The need for a better knowledge of its physical, chemical and optical properties, as well as there seasonal and inter-annual variations, was clearly expressed by the scientific community. In particular, long term measurements series available for the free troposphere are scarce, although it is crucial to better understand the origin, the different properties, and the role of aerosol particles on climate processes in the Troposphere. The site of the puy de Dôme (Central France, 1465 m.a.s.l.) lies in the free troposphere most of the time. Continuous measurements of aerosols properties (number size distribution, optical properties and chemical composition), combined with in-situ meteorological instrumentation and continuous measurements of reactive gaseous species (O3, NOx, NOy, HCHO, CO and SO2) have been performed over the past years. We will present the evolution over a 3-year period of aerosol chemical, optical and physical properties at this site. The puy de Dôme site is dominantly under the influence of westerly winds although advection of air masses from Northern and Eastern Europe as well as episodes of Saharan dust occurs frequently. Weekly filter samples have been collected and analyzed for their inorganic and organic contents. The variations of both carbonaceous matter (Elemental and Organic Carbon, (EC and OC), divided into water soluble and insoluble organic carbon (WSOC and WISOC and organic acids)) and inorganic species show significant seasonal variability The variations of the chemical properties are analyzed as a function of the air mass trajectory and linked to the optical (black carbon concentrations and diffusion coefficient) and physical (Number concentration and, for some periods, size distribution) properties. This analysis permits a classification of aerosol properties associated to the different air masses encountered at the puy de Dôme. This data set will be of interest model validation in an area (free troposphere, Western Europe) that is still poorly documented.

Background Neonates with pulmonary hypertension have been treated with inhaled nitric oxide because of studies suggesting that it is a selective pulmonary vasodilator. We conducted a randomized, multicenter, controlled trial to determine whether inhaled nitric oxide would reduce mortality or the initiation of extracorporeal membrane oxygenation in infants with hypoxic respiratory failure, Methods Infants born after a gestation of greater than or equal to 34 weeks who were 14 days old or less, had no structural heart disease, and required assisted ventilation and whose oxygenation index was 25 or higher on two measurements were eligible for the study. The infants were randomly assigned to receive nitric oxide at a concentration of 20 ppm or 100 percent oxygen (as a control). Infants whose partial pressure of arterial oxygen (PaO2) increased by 20 mm Hg or less after 30 minutes were studied for a response to 80-ppm nitric oxide or control gas, Results The 121 infants in the control group and the 114 in the nitric oxide group had similar base-line clinical characteristics. Sixty-four percent of the control group and 46 percent of the nitric oxide group died within 120 days or were treated with extracorporeal membrane oxygenation (P=0.006). Seventeen percent of the control group and 14 percent of the nitric oxide group died (P not significant), but significantly fewer in the nitric oxide group received extracorporeal membrane oxygenation (39 percent vs. 54 percent, P=0.014). The nitric oxide group had significantly greater improvement in PaO2 (mean [+/-SD] increase, 58.2+/-85.2 mm Hg, vs. 9.7+/-51.7 mm Hg in the controls; P Conclusions Nitric oxide therapy reduced the use of extracorporeal membrane oxygenation, but had no apparent effect on mortality, in critically ill infants with hypoxic respiratory failure. (C) 1997, Massachusetts Medical Society.