Die Luftverschmutzung ist weltweit nach wie vor eines der größten Umweltprobleme. Bei der Ursachenanalyse gestaltet es sich als besonders schwierig den höchst variablen Einfluss der meteorologischen Bedingungen auf die Schadstoffkonzentration zu eliminieren (Immission) und damit wirksame Luftreinhaltemaßnahmen zu entwickeln. Mit der vorliegenden Arbeit werden Methoden vorgestellt und diskutiert, die das natürlich vorkommende radioaktive Edelgas Radon als atmosphärischen Tracer nutzen, um den Einfluss der meteorologischen Bedingungen auf die Immissionskonzentration auszuschalten und damit unterschiedliche Schadstoffkonzentrationen objektiv vergleichbar zu machen. Für einen Zeitraum von vier Jahren wurden hierfür an einer Luftgütemessstation des städtischen Hintergrunds die Luftschadstoffe Stickstoffdioxid (NO2) und Feinstaub als PM10 und PM2.5 sowie das radioaktive Edelgas Radon gemessen. Zudem wurden Daten einer verkehrsnahen Station verwendet sowie meteorologische Daten. / Air pollution is one of the main environmental problems worldwide. Beside the emission the spread of air pollutants is affected by the shape of the earth surface, the land use and the meteorological conditions of the near surface atmosphere. In this conection the meteorological conditions are very difficult to estimate, because these conditions are a result of the combination of many variables which furthermore change in a short period. With this work are methods presented and discussed which use the naturally occurring noble gas Radon as a tracer in the atmospheric boundary layer. Measured data were analyzed with statistical methods and the Radon-Tracer-Method. For a period of four years there were measured the air pollutants nitrogen dioxide (NO2) and particulate matter (PM10, PM2.5) and the tracer Radon. The measurement took place at an air quality control station in the urban background. Furthermore, there were used data from an urban traffic station at a high frequented main street (hot spot) and meteorological data.

Introdução: A poluição atmosférica é proveniente de complexas interações que envolvem emissões de poluentes atmosféricos e que sabidamente causam consequências negativas para a saúde humana. De acordo com alguns estudos, a exposição à poluição, durante a gestação, pode causar baixo peso ao nascimento e prematuridade. Contudo, não há ainda consenso sobre os períodos de maior susceptibilidade para a exposição à poluição, e quais seriam os seus efeitos nos desfechos do gestação e na determinação do sexo do recém-nascido (RN). Objetivos: Com a finalidade de investigar o impacto da poluição na gestação e, consequentemente, no RN, os objetivos deste projeto são avaliar a influência da exposição à poluição, antes da concepção, na determinação do sexo do RN, e, durante a gestação, nos desfechos do parto e na curva de crescimento da circunferência cefálica (CC) entre o terceiro trimestre e o parto. Métodos: Um estudo prospectivo com 371 gestantes, intitulado ProcriAR, foi realizado na cidade de São Paulo. Os poluentes dióxido de nitrogênio (NO2) e ozônio (O3) foram medidos durante cada trimestre da gestação por meio da utilização de amostradores passivos individuais (APIs). Simultaneamente, foi realizada a análise dos poluentes NO2 e material particulado com tamanho menor que 10 Micro m (MP10) medidos pela estação fixa de ar de Taboão da Serra da Companhia Ambiental do Estado de São Paulo (CETESB), localizada na zona oeste de São Paulo e a mais próxima da residência das gestantes do projeto. Os desfechos avaliados foram: idade gestacional, peso, comprimento e medida da CC do RN; sexo do RN e crescimento do polo cefálico entre o terceiro trimestre e o parto. Quando a variável desfecho era contínua, foi realizada análise linear multivariada, controle de idade gestacional, sexo do RN, idade materna no momento da concepção, índice de massa corporal (IMC), paridade, tabagismo, consumo de álcool, cor, nível de escolaridade completado, estado civil, índice de pulsatilidade (IP) da artéria umbilical no terceiro trimestre, e via de parto para a variável CC. Resultados: Não foram observadas associações entre a exposição ao NO2 e O3, avaliados em cada trimestre da gestação, e a idade gestacional, o peso, o comprimento, a CC ao nascer e o crescimento do polo cefálico fetal entre o terceiro trimestre e o parto. A exposição ao NO2 e MP10 no ano prévio à concepção influenciou na chance de ser do sexo feminino, ou seja, para cada aumento de 1 unidade do poluente do NO2, constatou-se um aumento de 10% na chance de ser do sexo feminino (Razão de chances (RC) = 1,100; intervalo de confiança (IC) de 95% = 1,040, 1,164; p = 0,001). Em relação ao MP10, para cada aumento de 1 unidade desse poluente, observou-se um aumento de 18 % na chance de ser do sexo feminino (RC = 1,176; IC de 95% = 1,054, 1,311; p = 0,004). Conclusão: Nossos resultados sugerem que, no ambiente de São Paulo, a exposição à poluição no ano prévio à concepção esteve associada à determinação do sexo do RN / Background: Ambient pollution may lead to adverse obstetric outcomes, such as premature birth and low birth weight. Objectives: To determine the influence of maternal air pollution exposure on sex ratio, on birth outcomes and on the growth curve of cephalic pole between the third trimester and the birth. Methods: ProcriAR, a prospective cohort study of 371 pregnant women, was conducted in the city of São Paulo. Nitrogen dioxide (NO2) and ozone (O3) were measured during each trimester using passive personal monitors. At the same time, NO2 and particulate matter lower than 10 Micro m (PM10) were measured by a fixed station. We evaluated the gestational age, birth weight, birth lenght, head circumference, newborn sex and the growth curve of cephalic pole between the third trimester and the birth. When the outcome variable was continuous, multivariate analysis was performed, controlling for gestational age, newborn sex, maternal age at conception, body mass index, parity, smoking, alcohol consumption, race, highest education level completed, marital status, umbilical artery pulsatility values at third trimester and type of delivery for the outcome head circumference. We used multiple logistic regression models to evaluate the association of being female based on a quantitative increase in pollutant concentration, controlling for maternal age at conception, parity and smoking. Results: Elevated exposure to pollutants NO2 and PM10 were associated with increased odds of being female. Each unit increase of NO2 exposure increased the odds of being female by 10% (odds ratio (OR) = 1,100, 95% confidence interval (CI) = 1,040, 1,164; p = 0,001) and each unit increase of PM10 increased by 18% (OR = 1,176, 95% CI 1,054, 1,311, p = 0,004). Conclusion: In São Paulo, maternal exposure to pollutants prior to conception was significantly associated with the odds of being female

Syftet med arbetet har varit att undersöka hur arbetsmiljön och innemiljön med avseende på luftkvalitet har förändrats ombord fartyget M/S Aurora af Helsingborg efter konvertering från dieselelektrisk- till batteridrift. Resultatet har sedan jämförts med Arbetsmiljöverkets hygieniska gränsvärden, WHOs riktlinjer och tidigare mätning på Aurora som utfördes 2014, innan konverteringen till batteridrift. Då bestod framdrivningen av fyra Wärtsilä-Vasa 6R32E dieselmotorer som körde på miljödiesel. Under sju dagar i mars 2019, från nionde till sextonde, har mätdata samlats in på fartyget Aurora genom olika passiva provtagare för: Polycykliska aromatiska kolväten (PAH), lättflyktiga organiska ämnen (TVOC), temperatur, relativ luftfuktighet, partiklar, SO2 och NO2. Resultaten av mätvärdena visade att det är bra Luftkvalitet ombord på fartyget och att innemiljön blivit bättre sedan konverteringen. Alla uppmätta halter låg långt under de hygieniska gränsvärdena som Arbetsmiljöverket tagit fram. Nivåerna låg även under riktlinjerna bortsett från TVOC i separatorrummet där halterna är betydligt högre än riktvärdet. Arbetsuppgifterna ombord Aurora har förändrats till det bättre sedan konverteringen med bland annat mindre hantering av oljeprodukter. / The purpose of this study is to examine how the work environment and indoor air quality has changed onboard M/S Aurora af Helsingborg after the conversion from diesel electric to battery. The results have been compared to Swedish Work Environment Authority (Arbetsmiljöverket) hygienic exposure limits, World Health Organizations (WHO) guidelines and previous measurements from 2014 done on Aurora before the conversion to battery drive. At that time Aurora was propelled by four Wärtsilä-Vasa 6R32E diesel engines running on environmental diesel. During seven days in March from 9th to 16th 2019, data was collected on the vessel Aurora by different types of passive samplers: Polycyclic aromatic hydrocarbons (PAH), benzo(a)pyrene, total volatile organic substances (TVOC), benzene, temperature, relative humidity, particulate matter (PM), SO2, NO2. The result from the data collected showed that the indoor air quality onboard and the inside environment has improved after the conversion. All measured data were much lower than the hygienic limit values that Swedish Work Environment Authority has set. The values of the data were also lower than recommendations except from TVOC in purifier room. The duties on board Aurora has changed for the better since the conversion, including less management of oil products.

OBJETIVO: Avaliar a influência dos efeitos da poluição atmosférica sobre o volume e a vascularização placentários no primeiro trimestre. MÉTODOS: O presente estudo é uma coorte prospectiva  realizada de outubro de 2011 a março de 2014, em São Paulo, Brasil. Os critérios de inclusão foram: feto único, idade gestacional entre 11 semanas e 13 semanas e 6 dias, ausência de doença materna, ausência de malformações e utilização correta do amostrador passivo individual de poluentes. Os critérios de exclusão foram: gestação gemelar, malformações e abortamento diagnosticados à ultrassonografia, mudança de endereço para fora da área de recrutamento, desistência da paciente, doença materna diagnosticada durante o acompanhamento. A exposição à poluição foi avaliada por 7 a 18 dias, antes da avaliação ultrassonográfica, utilizando-se amostrador passivo individual dos poluentes NO2 e de O3. Após uso do filtro, as gestantes eram avaliadas na Clínica Obstétrica do Hospital das Clínicas da Faculdade de Medicina de São Paulo (FMUSP). Nesse local, elas foram submetidas à ultrassonografia morfológica entre 11 semanas e 13 semanas e 6 dias e à avaliação placentária pela técnica tridimensional associada ao power Doppler. Por meio desse exame foram avaliados quantitativamente o volume da placenta e seus índices vasculares placentários (com o software VOCAL), os quais compreendem: índice de vascularização (IV), índice de fluxo (IF) e índice de vascularização e fluxo (IVF). A influência dos níveis de poluentes na vascularização e volume placentários log-transformada foi analisada utilizando modelos de regressão linear múltipla que controlavam a idade gestacional, índice de massa corpórea, tabagismo, localização da placenta e paridade. RESULTADOS: Foram avaliadas 229 gestantes no primeiro. O aumento dos níveis de NO2 no primeiro trimestre teve um efeito negativo significativo sobre o IV (p = 0,012 e beta = 0,160) e IVF (p = 0,015 e beta = -0,159). Não houve influência de NO2 e O3 no volume placentário ou IF. CONCLUSÃO: A exposição materna ao NO2 foi significativamente associada com diminuição do índice de vascularização e do índice de vascularização e fluxo no primeiro trimestre da gravidez, o que sugere que esse poluente e outros poluentes primários e secundários, os quais estão associados ao NO2, influenciam na placentação, reduzindo sua vascularização / OBJECTIVE: To evaluate the influence of air pollution on the volume and placental vascularization in the first trimester. METHODS: This study is a prospective cohort conducted from October 2011 to March 2014 in São Paulo, Brazil. The inclusion criteria were single fetus, gestational age between 11 weeks and 13 weeks and 6 days, the absence of maternal disease, fetal defects and correct use of passive personal monitors pollutants. The exclusion criteria were twin pregnancy, abortion and malformations diagnosed on ultrasound, change of address out of the area of recruitment, patient abandonment, and maternal disease diagnosed during follow-up. The pollution exposure was evaluated by 7 to 18 days, before the ultrasound evaluation, using passive personal monitors pollutants of NO2 and O3. After using the filter, the pregnant women were evaluated at Obstetrics Department from Hospital das Clinicas of Faculdade de Medicina de São Paulo (FMUSP). In this place, they were subjected to morphological ultrasound between 11 weeks and 13 weeks and 6 days and placental evaluation by the three dimensional ultrasound power Doppler. Through the ultrasound examination were quantitatively evaluated the volume of the placenta and their placental vascular indices (with VOCAL software), which comprise the vascularization index (VI), flow index (FI) and vascularization flow index (VFI). The influence of pollutant levels on logtransformed placental vascularization and volume was analyzed using multiple linear regression models that controlled for gestational age, body mass index, smoking status, placental location and parity. RESULTS: In the first trimester 229 pregnant women were evaluation. NO2 levels increased in the first trimester had a significant negative effect on the VI (p=0.012 and beta= -0.160) and the VFI (p = 0.015 and beta= -0.159). No effect of NO2 and O3 on the log of placental volume or FI was observed. CONCLUSION: NO2 exposure was significantly associated with a diminished Vascularization Index and Vascularization and Flow Index in the first trimester of pregnancy, which suggests that this pollutant and other primary and secondary pollutants that are associated with NO2 influence placentation and decrease vascularization

OBJETIVO: Avaliar a influência dos efeitos da poluição atmosférica sobre o volume e a vascularização placentários no primeiro trimestre. MÉTODOS: O presente estudo é uma coorte prospectiva  realizada de outubro de 2011 a março de 2014, em São Paulo, Brasil. Os critérios de inclusão foram: feto único, idade gestacional entre 11 semanas e 13 semanas e 6 dias, ausência de doença materna, ausência de malformações e utilização correta do amostrador passivo individual de poluentes. Os critérios de exclusão foram: gestação gemelar, malformações e abortamento diagnosticados à ultrassonografia, mudança de endereço para fora da área de recrutamento, desistência da paciente, doença materna diagnosticada durante o acompanhamento. A exposição à poluição foi avaliada por 7 a 18 dias, antes da avaliação ultrassonográfica, utilizando-se amostrador passivo individual dos poluentes NO2 e de O3. Após uso do filtro, as gestantes eram avaliadas na Clínica Obstétrica do Hospital das Clínicas da Faculdade de Medicina de São Paulo (FMUSP). Nesse local, elas foram submetidas à ultrassonografia morfológica entre 11 semanas e 13 semanas e 6 dias e à avaliação placentária pela técnica tridimensional associada ao power Doppler. Por meio desse exame foram avaliados quantitativamente o volume da placenta e seus índices vasculares placentários (com o software VOCAL), os quais compreendem: índice de vascularização (IV), índice de fluxo (IF) e índice de vascularização e fluxo (IVF). A influência dos níveis de poluentes na vascularização e volume placentários log-transformada foi analisada utilizando modelos de regressão linear múltipla que controlavam a idade gestacional, índice de massa corpórea, tabagismo, localização da placenta e paridade. RESULTADOS: Foram avaliadas 229 gestantes no primeiro. O aumento dos níveis de NO2 no primeiro trimestre teve um efeito negativo significativo sobre o IV (p = 0,012 e beta = 0,160) e IVF (p = 0,015 e beta = -0,159). Não houve influência de NO2 e O3 no volume placentário ou IF. CONCLUSÃO: A exposição materna ao NO2 foi significativamente associada com diminuição do índice de vascularização e do índice de vascularização e fluxo no primeiro trimestre da gravidez, o que sugere que esse poluente e outros poluentes primários e secundários, os quais estão associados ao NO2, influenciam na placentação, reduzindo sua vascularização / OBJECTIVE: To evaluate the influence of air pollution on the volume and placental vascularization in the first trimester. METHODS: This study is a prospective cohort conducted from October 2011 to March 2014 in São Paulo, Brazil. The inclusion criteria were single fetus, gestational age between 11 weeks and 13 weeks and 6 days, the absence of maternal disease, fetal defects and correct use of passive personal monitors pollutants. The exclusion criteria were twin pregnancy, abortion and malformations diagnosed on ultrasound, change of address out of the area of recruitment, patient abandonment, and maternal disease diagnosed during follow-up. The pollution exposure was evaluated by 7 to 18 days, before the ultrasound evaluation, using passive personal monitors pollutants of NO2 and O3. After using the filter, the pregnant women were evaluated at Obstetrics Department from Hospital das Clinicas of Faculdade de Medicina de São Paulo (FMUSP). In this place, they were subjected to morphological ultrasound between 11 weeks and 13 weeks and 6 days and placental evaluation by the three dimensional ultrasound power Doppler. Through the ultrasound examination were quantitatively evaluated the volume of the placenta and their placental vascular indices (with VOCAL software), which comprise the vascularization index (VI), flow index (FI) and vascularization flow index (VFI). The influence of pollutant levels on logtransformed placental vascularization and volume was analyzed using multiple linear regression models that controlled for gestational age, body mass index, smoking status, placental location and parity. RESULTS: In the first trimester 229 pregnant women were evaluation. NO2 levels increased in the first trimester had a significant negative effect on the VI (p=0.012 and beta= -0.160) and the VFI (p = 0.015 and beta= -0.159). No effect of NO2 and O3 on the log of placental volume or FI was observed. CONCLUSION: NO2 exposure was significantly associated with a diminished Vascularization Index and Vascularization and Flow Index in the first trimester of pregnancy, which suggests that this pollutant and other primary and secondary pollutants that are associated with NO2 influence placentation and decrease vascularization

Antecedentes y objetivo: Un creciente número de estudios epidemiológicos han asociado la exposición prenatal a contaminación atmosférica urbana con un menor crecimiento fetal, pero pocos están basados en cohortes prospectivas con modelos de exposición que capten la variabilidad espacial a pequeña escala de la contaminación dentro de una misma ciudad. Métodos: A partir de modelos basados en medidas de contaminación con captadores pasivos y variables geográficas, se estimó la exposición prenatal a dióxido de nitrógeno (NO2) y compuestos orgánicos volátiles (COVs) en una cohorte de 611 embarazadas de Sabadell. El crecimiento fetal se midió como peso al nacer y también longitudinalmente mediante ecografías obstétricas.Resultados: Tras estratificar por determinados patrones de tiempo-actividad, se halló un efecto negativo de la exposición prenatal a COVs por incremento en el rango intercuartílico sobre el peso al nacer (-77 gr, p<0.05). Al evaluar el crecimiento fetal mediante ecografías se halló una asociación entre exposición a NO2 y COVs desde el inicio del embarazo y un menor crecimiento de varios parámetros fetales a partir de la semana 20 de gestación. Conclusiones: La variabilidad en la exposición a contaminación atmosférica asociada al tráfico dentro de una misma ciudad tiene un efecto negativo sobre el crecimiento fetal. Este efecto comienza a manifestarse hacia la mitad del embarazo y parece persisitir hasta el nacimiento. / Background and objective: A growing number of studies have found an association between prenatal exposure to urban air pollution and fetal growth, but few of them are based on prospective cohorts with exposure models developed to capture the small-scale spatial variability in air pollution levels within a city.Methods: We developed models based on air pollution measurements with passive samplers and geographic variables. They were applied to estimate prenatal exposure to nitrogen dioxide (NO2) and volatile organic compounds (VOCs) in a cohort of 611 pregnant women from Sabadell. Fetal growth was assessed as birth weight and also through obstetric ultrasounds.Results: After stratifying by some specific time-activity patterns, a negative effect of prenatal exposure to VOCs was found on birth weight (-77 gr, p<0.05 for an interquartilic range increase in VOCs levels). When fetal growth was longitudinally assessed through ultrasound examinations, an association was found between exposure to NO2 and VOCs from early pregnancy and impaired growth in several fetal parameters from week 20 onwards. Conclusiones: Within-city variations in exposure to traffic-related air pollution have an effect on fetal growth. This effect already manifests during mid-pregnancy and seems to persist until birth.

No description available.

Species must interact with air—aqueous interfaces in order to transport between either phase, however organic coated water surfaces are ubiquitous in the environment, and the physical and chemical processes that occur at organic coated aqueous surfaces are often different than those at pure air—water interfaces. Three studies were performed investigating the transport of species across air—aqueous interfaces with organic coatings in an effort to gain further insight into these processes. Gas and solution phase absorption spectroscopy were used to study the effect of octanol coatings on the formation of molecular iodine (I2) by the heterogeneous ozonation of iodide and its partitioning between phases. Compared to uncoated solutions, the presence of octanol monolayers had a minor effect on the total amount of I2 produced, however, it did significantly enhance the gas to solution partitioning of I2. Incoherent broadband cavity-enhanced absorption spectroscopy (IBBC-EAS) was used to measure the gas-phase nitrogen dioxide (NO2) evolved via photolysis of aqueous nitrate solutions either uncoated or containing octanol, octanoic acid and stearic acid monolayers. Both octanol and stearic acid reduced the rate of gaseous NO2 evolution, and octanol also decreased the steady-state amount of gaseous NO2. Alternatively, octanoic acid enhanced the rate of gaseous NO2 evolution. Finally, the loss of aqueous carbon dioxide (CO2) from aqueous solutions saturated with CO2 was measured using a CO2 electrode in the absence and presence of stearic acid monolayers and octanol coatings, and a greenhouse gas analyzer was used to measure the evolution of gaseous CO2 from solutios with octanol monolayers. Enhanced losses of aqueous and evolved gaseous CO2 were observed with organic coated solutions compared to those uncoated. The results of these studies suggest that organic coatings influence the transport of I2, NO2 and CO2 via one, or a combination of: barrier effects, surface tension effects, chemistry effects and aqueous – surface – gas partitioning effects. These results, particularly the enhanced partitioning of these species to octanol coated aqueous surfaces, have important implications for species transport at air—aqueous interfaces, and may provide useful insight for future studies and parameters for atmospheric models of these species.

Species must interact with air—aqueous interfaces in order to transport between either phase, however organic coated water surfaces are ubiquitous in the environment, and the physical and chemical processes that occur at organic coated aqueous surfaces are often different than those at pure air—water interfaces. Three studies were performed investigating the transport of species across air—aqueous interfaces with organic coatings in an effort to gain further insight into these processes. Gas and solution phase absorption spectroscopy were used to study the effect of octanol coatings on the formation of molecular iodine (I2) by the heterogeneous ozonation of iodide and its partitioning between phases. Compared to uncoated solutions, the presence of octanol monolayers had a minor effect on the total amount of I2 produced, however, it did significantly enhance the gas to solution partitioning of I2. Incoherent broadband cavity-enhanced absorption spectroscopy (IBBC-EAS) was used to measure the gas-phase nitrogen dioxide (NO2) evolved via photolysis of aqueous nitrate solutions either uncoated or containing octanol, octanoic acid and stearic acid monolayers. Both octanol and stearic acid reduced the rate of gaseous NO2 evolution, and octanol also decreased the steady-state amount of gaseous NO2. Alternatively, octanoic acid enhanced the rate of gaseous NO2 evolution. Finally, the loss of aqueous carbon dioxide (CO2) from aqueous solutions saturated with CO2 was measured using a CO2 electrode in the absence and presence of stearic acid monolayers and octanol coatings, and a greenhouse gas analyzer was used to measure the evolution of gaseous CO2 from solutios with octanol monolayers. Enhanced losses of aqueous and evolved gaseous CO2 were observed with organic coated solutions compared to those uncoated. The results of these studies suggest that organic coatings influence the transport of I2, NO2 and CO2 via one, or a combination of: barrier effects, surface tension effects, chemistry effects and aqueous – surface – gas partitioning effects. These results, particularly the enhanced partitioning of these species to octanol coated aqueous surfaces, have important implications for species transport at air—aqueous interfaces, and may provide useful insight for future studies and parameters for atmospheric models of these species.

Au cours des dernières années, les efforts de recherche et de développement pour les capteurs de gaz se sont orientés vers l'intégration de nanomatériaux afin d'améliorer les performances des dispositifs. Ces nouvelles générations promettent de nombreux avantages notamment en matière de miniaturisation et de réduction de la consommation énergétique. Par ailleurs, la détection sous gaz (sensibilité, seuil de détection, temps de réponse, ...) s'en retrouve améliorée à cause de l'augmentation du ratio surface/volume de la partie sensible. Ainsi, de tels capteurs peuvent être intégrés dans des systèmes de détections ultrasensibles, autonomes, compactes et transportables. Dans cette thèse, nous proposons d'utiliser des réseaux verticaux de nanofils semi-conducteurs pour créer des dispositifs de détection de gaz hautement sensibles, sélectifs, avec une faible limite de détection (de l'ordre du ppb) et intégrable dans des technologies CMOS, tout en étant générique et adaptable à plusieurs types de matériaux afin de discriminer plusieurs gaz. Une première partie expose la mise au point d'un procédé grande échelle, reproductible, compatible avec l'industrie actuelle des semi-conducteurs (CMOS), pour obtenir un capteur basé sur une architecture 3D à nanofils. Le dispositif est composé de deux contacts symétriques en aluminium à chaque extrémité des nanofils, dont l'un est obtenu par l'approche dite du " pont à air ", permettant la définition d'un contact tridimensionnel au sommet du nanofil. La seconde partie présente les performances sous gaz des dispositifs développés et les mécanismes de fonctionnement. Le capteur démontre des performances record en matière de détection du dioxyde d'azote (30% à 50 ppb) en comparaison à l'état de l'art (25% à 200 ppb). De plus, cette approche permet de mesurer de très faibles concentrations de ce gaz (< 1 ppb) de manière sélective, dans des conditions proches des conditions réelles : humidité (testé jusqu'à 70% d'humidité) et mélange avec d'autres gaz plus concentrés et la réversibilité du capteur est naturelle et se fait à température ambiante sans nécessité des conditions particulières. / In recent years, efforts of research and development for gas sensors converged to use nanomaterials to optimize performance. This new generation promises many advantages especially in miniaturization and reduction of energy consumption. Furthermore, the gas detection parameters (sensitivity, detection limit, response time ...) are improved due to the high surface/volume ratio of the sensitive part. Thus, this sensors can be integrated in ultrasensitive detection systems, autonomous, compact and transportable. In this thesis, we propose to use 3D semiconductor nanowires networks to create highly sensitive and selective gas sensors. The objective of this work is to provide a highly sensitive sensor, featuring a low detection limit (in the ppb range) and embeddable in CMOS devices. In addition process is generic and adaptable to many types of materials to discriminate several gas and converge to electronic nose. The first part of the dissertation is based on development of a large scale, reproducible, compatible with Si processing industry and conventional tools (CMOS), to obtain a sensor based on a 3D nanowire architecture. The device is composed by two symmetrical aluminum contacts at each extremity of the nanowires, including a top contact done by air bridge approach. The second part of this work presents the gas performances of components and working mechanisms associated. A very high response (30%) is obtained at 50 ppb of NO2, compare to the state of the art, 25% reached for 200 ppb. This approach can measure selectively very low concentrations of gas (<1 ppb) in real working conditions: moisture (tested up to 70% moisture) and mixing with other more concentrated gas (interfering gas). In addition, the reversibility of the sensor is natural and occurs at room temperature without requiring specific conditions.