Noise in urban areas: How does the definition of "neighborhood" impact exposure assessment?

International audienceEnvironmental epidemiological studies commonly quantify subjects' noise exposure level in their neighborhood. How this neighborhood is defined can vary across studies, leading to different approaches whose impacts on exposure levels remain unclear. This article examines the impact of the neighborhood's definition on environmental noise exposure estimates. L Aeq,24h exposures in the vicinity of 10,825 residential buildings were estimated using a high-definition noise map, built on a middle-sized French city. Various definitions of neighborhood (address point, façade, buffers, and official zoning) were used to produce different exposure estimates. Influence of urban environmental factors was analyzed using multilevel modeling. The results showed a significant increase of the exposure estimates (+3.9 dB) and a significant decrease of the variability, when the sample size of the considered neighborhood increased (P<0.01). The difference between the estimates from the 50-m-radius buffers and the 400-m-radius buffers ranged across buildings between –9.4 and +22.3 dB. This variation was influenced by urban environmental characteristics (P<0.01). Furthermore, the same approach was conducted individually considering assessments of exposure to road traffic noise railway noise and two atmospheric pollutants (NO2 and PM 10). The results highlight the need in further exposure and/or epidemiological studies to carefully consider neighborhood definition and environmental composition

Association between Ambient Noise Exposure and School Performance of Children Living in An Urban Area: A Cross-Sectional Population-Based Study

16 pages Article disponible à l'adresse suivante : http://link.springer.com/article/10.1007%2Fs11524-013-9843-6International audienceMost of the studies investigating the effects of the external noise on children's school performance have concerned pupils in schools exposed to high levels due to aircraft or freeway traffic noise. However, little is known about the consequences of the chronic ambient noise exposure at a level commonly encountered in residential urban areas. This study aimed to assess the relationship between the school performance of 8- to 9-year-old-children living in an urban environment and their chronic ambient noise exposure at home and at school. The children's school performances on the national standardized assessment test in French and mathematics were compared with the environmental noise levels. Children's exposure to ambient noise was calculated in front of their bedrooms (Lden) and schools (LAeq,day) using noise prediction modeling. Questionnaires were distributed to the families to collect potential confounding factors. Among the 746 respondent children, 586 were included in multilevel analyses. On average, the LAeq,day at school was 51.5 dB (SD= 4.5 dB; range = 38-58 dB) and the outdoor Lden at home was 56.4 dB (SD= 4.4 dB; range = 44-69 dB). LAeq,day at school was associated with impaired mathematics score (p = 0.02) or impaired French score (p = 0.01). For a + 10 dB gap, the French and mathematics scores were on average lower by about 5.5 points. Lden at home was significantly associated with impaired French performance when considered alone (p < 10(-3)) and was borderline significant when the combined home-school exposure was considered (p = 0.06). The magnitude of the observed effect on school performance may appear modest, but should be considered in light of the number of people who are potentially chronically exposed to similar environmental noise levels

Peripheral, Central and Behavioral Responses to the Cuticular Pheromone Bouquet in Drosophila melanogaster Males

Pheromonal communication is crucial with regard to mate choice in many animals including insects. Drosophila melanogaster flies produce a pheromonal bouquet with many cuticular hydrocarbons some of which diverge between the sexes and differently affect male courtship behavior. Cuticular pheromones have a relatively high weight and are thought to be — mostly but not only — detected by gustatory contact. However, the response of the peripheral and central gustatory systems to these substances remains poorly explored. We measured the effect induced by pheromonal cuticular mixtures on (i) the electrophysiological response of peripheral gustatory receptor neurons, (ii) the calcium variation in brain centers receiving these gustatory inputs and (iii) the behavioral reaction induced in control males and in mutant desat1 males, which show abnormal pheromone production and perception. While male and female pheromones induced inhibitory-like effects on taste receptor neurons, the contact of male pheromones on male fore-tarsi elicits a long-lasting response of higher intensity in the dedicated gustatory brain center. We found that the behavior of control males was more strongly inhibited by male pheromones than by female pheromones, but this difference disappeared in anosmic males. Mutant desat1 males showed an increased sensitivity of their peripheral gustatory neurons to contact pheromones and a behavioral incapacity to discriminate sex pheromones. Together our data indicate that cuticular hydrocarbons induce long-lasting inhibitory effects on the relevant taste pathway which may interact with the olfactory pathway to modulate pheromonal perception

Transformations catalytiques de composés organiques sur matrices minérales (étude sur une molécule modèle, le cholestérol)

POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Acid catalysed backbone rearrangement of cholesta-2,4,6-triene: On the origin of ring A and ring B aromatic steroids in recent sediments

Rearrangement of cholesta-2,4,6-triene in the presence of p-toluenesulfonic acid in acetic acid at 70° C leads to 4-methyl-19-nor-cholesta-1,3,5(10)-triene and 1(10 !6)-abeo-14b-cholesta-5,7,9(10)-triene in less than 2 h. Postulated mechanisms of formation of these products are supported by molecular mechanics calculations of the relative stabilities of reaction intermediates. The results suggest that D5,7-sterols, the most common natural precursors of triunsaturated steroidal hydrocarbons in contemporary sediments, constitute another major source for monoaromatic A and B steroids in addition to D5-sterols

Linking traffic and noise models to explore spatio-temporal distribution of noise pollution: an example in Besançon (France)

International audienceRoad transportation is one of the major environmental noise sources in urban areas, which is characterized by an important temporal and spatial variation. Therefore, linking mobility and traffic model with noise model each representing spatial and temporal dimensions is a great interest. An integrated and original approach was developed to explore noise pollution in urban areas with a spatiotemporal and prospective point of view. An agent-based Land-Use and Transport Integrated (LUTI) model - MobiSim- was used to assess traffic modulation by simulating hourly flows and mobility. Individual choices of agents (representing the city's inhabitants) were transformed to flux of vehicles and persons and affected on the available network systems (routes, public transports, etc.). MobiSim output was linked with the noise mapping MITHRA-SIG software in order to calculate hourly noise maps. Results were then compared with strategic noise map in the city of Besançon (France) calculated according to the European environmental noise directive (2002/49/EC). Finally, several scenarios of mobility were simulated, which impacted noise environment differently in time and space. This approach, combining traffic and mobility simulation and environment pollution model, offers an interesting solution to assess the impacts of urban planning and management projects according to the principles of sustainable development (traffic management and pollution, spatial and social equity, etc.)

Impact sanitaire de l’exposition sonore en milieu urbain, la combinaison de 3 « E » : épidémiologie, expologie, environnement

National audienceLa quantification de l’impact du bruit sur la santé, relève d’une démarche complexe et mobilise des champs de compétence larges et différents. L’objectif de cet article est de proposer le point de vue volontairement orienté sur l’un de ses champs de compétence, centré sur une approche en population humaine. Sont ainsi décrits les concepts de l’épidémiologie, de l’expologie et leurs applications sur les approches en lien avec l’environnement, en particulier le milieu urbain. La dimension sociétale d’inégalité sociale et environnementale est également rappelée. Le principe de l’évaluation d’un impact sanitaire (appelé également évaluation du risque sanitaire) est succinctement présenté ainsi qu’une application aux effets des nuisances sonores