Hélène Houot

Assessing residential exposure to urban noise using environmental models: does the size of the local living neighborhood matter?

Environmental epidemiological studies rely on the quantification of the exposure level in a surface defined as the subject’s exposure area. For residential exposure, this area is often the subject’s neighborhood. However, the variability of the size and nature of the neighborhoods makes comparison of the findings across studies difficult. This article examines the impact of the neighborhood’s definition on environmental noise exposure levels obtained from four commonly used sampling techniques: address point, façade, buffers, and official zoning. A high-definition noise model, built on a middle-sized French city, has been used to estimate LAeq,24u2009h exposure in the vicinity of 10,825 residential buildings. Twelve noise exposure indicators have been used to assess inhabitants’ exposure. Influence of urban environmental factors was analyzed using multilevel modeling. When the sampled area increases, the average exposure increases (+3.9u2009dB), whereas the SD decreases (−1.6u2009dB) (P<0.01). Most of the indicators differ statistically. When comparing indicators from the 50-m and 400-m radius buffers, the assigned LAeq,24u2009h level varies across buildings from –9.4 to +22.3u2009dB. This variation is influenced by urban environmental characteristics (P<0.01). On the basis of this study’s findings, sampling technique, neighborhood size, and environmental composition should be carefully considered in further exposure studies.

Do outdoor environmental noise and atmospheric NO2 levels spatially overlap in urban areas

The urban environment holds numerous emission sources for air and noise pollution, creating optimum conditions for environmental multi-exposure situations. Evaluation of the joint-exposure levels is the main obstacle for multi-exposure studies and one of the biggest challenges of the next decade. The present study aims to describe the noise/NO2 multi-exposure situations in the urban environment by exploring the possible discordant and concordant situations of both exposures. Fine-scale diffusion models were developed in the European medium-sized city of Besançon (France), and a classification method was used to evaluate the multi-exposure situations in the façade perimeter of 10,825 buildings. Although correlated (Pearsons rxa0=xa00.64, pxa0<xa00.01), urban spatial distributions of the noise and NO2 around buildings do not overlap, and 30% of the buildings were considered to be discordant in terms of the noise and NO2 exposure levels. This discrepancy is spatially structured and associated with variables describing the buildings environment. Our results support the presence of several co-existing, multi-exposure situations across the city impacted by both the urban morphology and the emission and diffusion/propagation phases of each pollutant. Identifying the mechanisms of discrepancy and convergence of multi-exposure situations could help improve the health risk assessment and public health.

Simulation fractale d'urbanisation. MUP-city, un modèle multi-échelle pour localiser de nouvelles implantations résidentielles

Larticle presente le prototype dun systeme daide a la decision pour lamenagement urbain qui aide a determiner ou ouvrir de nouveaux espaces a lurbanisation sans augmenter certains effets nefastes de letalement urbain (nombre et longueur des deplacements en automobile, fragmentation des espaces bâtis et non bâtis). Le systeme, intitule MUP-City, est base sur un principe de modelisation fractale multi-echelle et prend en compte laccessibilite locale a des amenites urbaines et rurales. Sur le secteur Nord de lagglomeration de Besancon (France), deux series de scenarios durbanisation ont ete simulees avec MUP-City. La premiere serie permet devaluer qualitativement la stabilite du modele face aux variations de quelques parametres determinants. La deuxieme serie de simulations sert a explorer les points forts et points faibles dune modelisation multi-echelle versus une modelisation mono-echelle.

An integrated multifractal modelling to urban and regional planning

In this paper, we propose a conceptual framework for the design of multifractal urban or regional development plans that adhere to five planning principles: hierarchical polycentric urban development; transit-oriented development; locally dense residential development; penetration of green areas into built-up areas across several nested scales; preservation of interconnected networks of natural and green areas having various sizes. This conceptual planning framework is based on multifractal spatial modelling, which is intrinsically multiscalar. The GIS-based software application Fractalopolis (current version 1.0) is used to apply this conceptual framework to real-world case studies. Fractalopolis helps to define where to create new housing units and new facilities in accordance with the planning principles set out above. We use Fractalopolis to create a multifractal development plan for a medium-sized French metropolitan area, namely Besancon, for the year 2026. This plan allows a realistic “soft” transformation the Besancon metropolitan area in keeping with the five planning principles set out above and makes the region more multifractal.

Multiple pregnancies and air pollution in moderately polluted cities: Is there an association between air pollution and fetal growth?

BACKGROUNDnMultiple pregnancies (where more than one fetus develops simultaneously in the womb) are systematically excluded from studies of the impact of air pollution on pregnancy outcomes. This study aims to analyze, in a population of multiple pregnancies, the relationship between fetal growth restriction (FGR), small for gestational age (SGA) and exposure to air pollution in moderately polluted cities.nnnMETHODSnAll women with multiple pregnancies living in the city of Besançon or in the urban area of Dijon and who delivered at a university hospital between 2005 and 2009 were included. FGR and SGA were obtained from medical records. Outdoor residential nitrogen dioxide (NO2) exposure was assessed using the mothers address, considering a 50u202fm radius buffer over the following defined pregnancy periods: each trimester, entire pregnancy and two months before delivery. Logistic regression analyses were performed.nnnRESULTSnThis study included 249 multiple pregnancies with 506 newborns. The median of NO2 concentration considering a 50u202fm radius buffer during entire pregnancy was 23.1u202fμg/m3 (minimum at 10.1u202fμg/m3 and maximum at 46.7u202fμg/m3). No association was observed between NO2 and SGA whatever the pregnancy period (the odds ratio (OR) range 0.78 to 0.88). Regarding FGR, the OR associated with an increase of 10u202fμg/m3 of NO2 exposure during entire pregnancy was 1.52 (95% Confidence Interval (CI): 1.02-2.26). Similar results were observed for NO2 exposure during the various pregnancy periods.nnnCONCLUSIONSnThese results are in line with an association between NO2 and fetal growth in multiple pregnancies for an exposure mostly below the threshold set out in European legislation.

Does low to moderate environmental exposure to noise and air pollution influence preterm delivery in medium-sized cities?

BackgroundnPreterm birth (PB) is an important predictor of childhood morbidity and educational performance. Beyond the known risk factors, environmental factors, such as air pollution and noise, have been implicated in PB. In urban areas, these pollutants coexist. Very few studies have examined the effects of multi-exposure on the pregnancy duration. The objective of this study was to analyse the relationship between PB and environmental chronic multi-exposure to noise and air pollution in medium-sized cities.nnnMethodsnA case-control study was conducted among women living in the city of Besançon (121 671 inhabitants) or in the urban unit of Dijon (243 936 inhabitants) and who delivered in a university hospital between 2005 and 2009. Only singleton pregnancies without associated pathologies were considered. Four controls were matched to each case in terms of the mothers age and delivery location. Residential noise and nitrogen dioxide (NO2) exposures were calculated at the mothers address. Conditional logistic regression models were applied, and sensitivity analyses were performed.nnnResultsnThis study included 302 cases and 1204 controls. The correlation between noise and NO2 indices ranged from 0.41 to 0.59. No significant differences were found in pollutant exposure levels between cases and controls. The adjusted odds ratios ranged between 0.96 and 1.08. Sensitivity analysis conducted using different temporal and spatial exposure windows demonstrated the same results.nnnConclusionsnThe results are in favour of a lack of connection between preterm delivery and multi-exposure to noise and air pollution in medium-sized cities for pregnant women without underlying disease.

Noise Annoyance in Urban Children: A Cross-Sectional Population-Based Study

Acoustical and non-acoustical factors influencing noise annoyance in adults have been well-documented in recent years; however, similar knowledge is lacking in children. The aim of this study was to quantify the annoyance caused by chronic ambient noise at home in children and to assess the relationship between these children′s noise annoyance level and individual and contextual factors in the surrounding urban area. A cross sectional population-based study was conducted including 517 children attending primary school in a European city. Noise annoyance was measured using a self-report questionnaire adapted for children. Six noise exposure level indicators were built at different locations at increasing distances from the child′s bedroom window using a validated strategic noise map. Multilevel logistic models were constructed to investigate factors associated with noise annoyance in children. Noise indicators in front of the child′s bedroom (p ≤ 0.01), family residential satisfaction (p ≤ 0.03) and socioeconomic characteristics of the individuals and their neighbourhood (p ≤ 0.05) remained associated with child annoyance. These findings illustrate the complex relationships between our environment, how we may perceive it, social factors and health. Better understanding of these relationships will undoubtedly allow us to more effectively quantify the actual effect of noise on human health.

Modeling urban noise exposure and contribution of noise reflection against façades of buildings: Does correction matter?

European noise directives advise to apply corrections when measuring and modelling noise levels close to a building in the aim of excluding the contribution of noise reflection against the facade. The advised -3 dB correction is still subject to discussion. In order to investigate the needed correction for a household exposure studies, a high definition noise model was used to estimate noise levels at 10,394 inhabitable buildings. Three buffers were used to sample area surrounding facades of buildings. The surfaces were defined between the following distances: i) 0 and 2m, ii) 0 and 6m, iii) 2 and 6m. No differences between the distribution structures were observed. Mean noise levels do not differ significantly between the buffers methods (respectively i) 49.6±6.7 dB, ii) 49.7±6.7 dB, iii) 49.8±6.7 dB ; p<0.01). Same observation can be made for maximum noise levels (respectively i) 52.0±7.2 dB, ii) 52.5±7.2 dB, iii) 52.4±7.2 dB ; p<0.01). These results show no or light differences between indices computed by the three sampling methods. They are in favour of no or at least a low correction value to deal with the contribution of noise reflection against the facade of a building.