Building energy saving techniques and indoor air quality : a dilemma

In European countries and North America, people spend 80 to 90% of time inside buildings and thus breathe indoor air. In Switzerland, special attention has been devoted to the 16 stations of the national network of observation of atmospheric pollutants (NABEL). The results indicate a reduction in outdoor pollution over the last ten years. With such a decrease in pollution over these ten years the question becomes: how can we explain an increase of diseases? Indoor pollution can be the cause. Indoor contaminants that may create indoor air quality (IAQ) problems come from a variety of sources. These can include inadequate ventilation, temperature and humidity dysfunction, and volatile organic compounds (VOCs). The health effects from these contaminants are varied and can range from discomfort, irritation and respiratory diseases to cancer. Among such contaminants, environmental tobacco smoke (ETS) could be considered the most important in terms of both health effects and engineering controls of ventilation. To perform indoor pollution monitoring, several selected ETS tracers can be used including carbon monoxide (CO), carbon dioxide (CO2), respirable particles (RSP), condensate, nicotine, polycyclic aromatic hydrocarbons (PAHs), nitrosamines, etc. In this paper, some examples are presented of IAQ problems that have occurred following the renewal of buildings and energy saving concerns. Using industrial hygiene sampling techniques and focussing on selected priority pollutants used as tracers, various problems have been identified and solutions proposed. [Author]

Evaluating thermal treeline indicators based on air and soil temperature using an air-to-soil temperature transfer model

In recent research, both soil (root-zone) and air temperature have been used as predictors for the treeline position worldwide. In this study, we intended to (a) test the proposed temperature limitation at the treeline, and (b) investigate effects of season length for both heat sum and mean temperature variables in the Swiss Alps. As soil temperature data are available for a limited number of sites only, we developed an air-to-soil transfer model (ASTRAMO). The air-to-soil transfer model predicts daily mean root-zone temperatures (10cm below the surface) at the treeline exclusively from daily mean air temperatures. The model using calibrated air and root-zone temperature measurements at nine treeline sites in the Swiss Alps incorporates time lags to account for the damping effect between air and soil temperatures as well as the temporal autocorrelations typical for such chronological data sets. Based on the measured and modeled root-zone temperatures we analyzed. the suitability of the thermal treeline indicators seasonal mean and degree-days to describe the Alpine treeline position. The root-zone indicators were then compared to the respective indicators based on measured air temperatures, with all indicators calculated for two different indicator period lengths. For both temperature types (root-zone and air) and both indicator periods, seasonal mean temperature was the indicator with the lowest variation across all treeline sites. The resulting indicator values were 7.0 degrees C +/- 0.4 SD (short indicator period), respectively 7.1 degrees C +/- 0.5 SD (long indicator period) for root-zone temperature, and 8.0 degrees C +/- 0.6 SD (short indicator period), respectively 8.8 degrees C +/- 0.8 SD (long indicator period) for air temperature. Generally, a higher variation was found for all air based treeline indicators when compared to the root-zone temperature indicators. Despite this, we showed that treeline indicators calculated from both air and root-zone temperatures can be used to describe the Alpine treeline position.

Propagation du virus de la grippe dans les transports aériens et survie du virus dans l'air ambiant

Chaque hiver en France, la grippe saisonnière touche entre 2 et 7 millions de personnes, dont environ 1 000 cas mortels, surtout parmi les personnes de plus de 65 ans. Elle constitue ainsi la première cause de mortalité par maladie infectieuse. L'agent causal est un virus à ARN très contagieux, pouvant appartenir à différent type (A, B ou C). Le type A est composé d'une large gamme de sous-types classés selon les différentes sortes et associations de protéines de surface du virus. Parmi ceux-ci, les sous-types H1N1 et H3N2 circulent actuellement chez l'Homme. La transmission inter-humaine de la maladie se fait principalement par voie aéroportée par le biais des gouttelettes riches en virus provenant des accès de toux et des éternuements des sujets infectés. Le coût sanitaire et social annuel de la grippe est estimé à 460 millions d'euros pour une épidémie moyenne. La prévention de la grippe repose sur une vaccination annuelle, proposée dans la plupart des pays industrialisés aux personnes à risque. Cependant, la couverture vaccinale en France n'était que de 23 % de la population générale en 2011-2012 (62 % chez les plus de 50 ans). Dès lors, environ 80 % des individus sont susceptibles de contracter la maladie. Les transports en commun constituent des environnements idéaux pour la dissémination des virus. En effet, la grande promiscuité entre les passagers potentiellement malades et les passagers sains favorise la propagation de la maladie. Dans ces conditions, l'évaluation du risque d'infection est utile pour appliquer une prévention ciblée. Le but du premier article analysé (Gupta et al., 2012) était, précisément, d'évaluer le risque, pour un passager sain, de contracter le virus de la grippe dans un avion transportant un passager malade. Les auteurs du second article analysé (Pyankov et al., 2012) ont estimé le temps de survie de différents sous-types de virus de la grippe dans l'air ambiant d'une chambre expérimentale.

La prévention du tabagisme passif [Prevention of air pollution by indoor tobacco smoke in France]

A majority of smokers and non-smokers mind tobacco smoke. Passive smoking causes death by sudden infant death, lung cancer and coronary heart disease. 3000 to 6000 persons are killed every year in France. The lack of implementation of the Evin's law published in 1991 explains why non-smokers are not given the protection they can expect. The trend of scientific knowledge and of French and international public opinions support a growing demand for a complete protection of non-smokers with a total ban of smoking in all public or working places.

Under- and over-water halves of Gyrinidae beetle eyes harbor different corneal nanocoatings providing adaptation to the water and air environments.

Whirligig beetles (Gyrinidae) inhabit water surfaces and possess unique eyes which are split into the overwater and underwater parts. In this study we analyze the micro- and nanostructure of the split eyes of two Gyrinidae beetles genera, Gyrinus and Orectochilus. We find that corneae of the overwater ommatidia are covered with maze-like nanostructures, while the corneal surface of the underwater eyes is smooth. We further show that the overwater nanostructures possess no anti-wetting, but the anti-reflective properties with the spectral preference in the range of 450-600 nm. These findings illustrate the adaptation of the corneal nanocoating of the two halves of an insect's eye to two different environments. The novel natural anti-reflective nanocoating we describe may find future technological applications.