Particle and VOC emission factor measurements for anthropogenic sources in West Africa

A number of campaigns have been carried out to establish the emission factors of pollutants from fuel combustion in West Africa, as part of work package 2 ("Air Pollution and Health") of the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) FP7 program. Emission sources considered here include wood (hevea and iroko) and charcoal burning, charcoal making, open trash burning, and vehicle emissions, including trucks, cars, buses and two-wheeled vehicles. Emission factors of total particulate matter (TPM), elemental carbon (EC), primary organic carbon (OC) and volatile organic compounds (VOCs) have been established. In addition, emission factor measurements were performed in combustion chambers in order to reproduce field burning conditions for a tropical hardwood (hevea), and obtain particulate emission factors by size (PM0.25, PM1, PM2.5 and PM10). Particle samples were collected on quartz fiber filters and analyzed using gravimetric method for TPM and thermal methods for EC and OC. The emission factors of 58 VOC species were determined using offline sampling on a sorbent tube. Emission factor results for two species of tropical hardwood burning of EC, OC and TPM are 0.98 ± 0.46 g kg-1 of fuel burned (g kg-1), 11.05 ± 4.55 and 41.12 ± 24.62 g kg-1, respectively. For traffic sources, the highest emission factors among particulate species are found for the two-wheeled vehicles with two-stroke engines (2.74 g kg-1 fuel for EC, 65.11 g kg-1 fuel for OC and 496 g kg-1 fuel for TPM). The largest VOC emissions are observed for two-stroke two-wheeled vehicles, which are up to 3 times higher than emissions from light-duty and heavy-duty vehicles. Isoprene and monoterpenes, which are usually associated with biogenic emissions, are present in almost all anthropogenic sources investigated during this work and could be as significant as aromatic emissions in wood burning (1 g kg-1 fuel). EC is primarily emitted in the ultrafine fraction, with 77 % of the total mass being emitted as particles smaller than 0.25 μm. The particles and VOC emission factors obtained in this study are generally higher than those in the literature whose values are discussed in this paper. This study underlines the important role of in situ measurements in deriving realistic and representative emission factors

Evaluation de l'impact sur la santé de l'aérosol de combustion pour différentes sources urbaines en Afrique de l'Ouest en saison sèche et humide : caractérisation physico-chimique et toxicologique

This thesis is in line with the scientific objectives of the DACCIWA-WP2 program. It is our responsibility to establish a link between emissions, air pollution and health impacts in terms of inflammation of the respiratory system for urban combustion sources, typical of West Africa: traffic, domestic fires and waste burning in Abidjan (Côte d'Ivoire) and Cotonou (Benin) during the dry and wet seasons 2015-2017. Our results show that the particulate concentrations observed at all sites far exceed the recommendations of WHO. The site influenced by domestic fires is the most polluted site, dominated by a significant fraction of ultrafine (UF) and fine (F) particles. The comparison of traffic sites shows that the average concentrations for each size class are twice higher in Cotonou than in Abidjan. The physicochemical characterization of these particles (organic carbon, elemental carbon, soluble organic carbon, ions, dust, trace elements) underlines that organic carbon and dust are the two most important contributors for Fand UF particles with more organic carbon in Abidjan and dust in Cotonou respectively. Parallel biological studies were conducted to characterize the pro-inflammatory response induced by particles collected for each site quantifying the release of the IL-6cytokines by human bronchial epithelial cells. As a result, particles from the domestic fire site are the most pro-inflammatory particles whatever the season, while the fine and ultra-fine fractions of particles from the two traffic sites cause significant comparable effects for each season, with the Cotonou site distinguishing itself by the reactivity of its coarse fraction, linked to the presence of dust. The F and UF particles of the combustion sources therefore seem to have a significant impact. This is confirmed by the crossed analysis between physicochemical and toxicological data, which shows that the carbonaceous aerosol component of the aerosol (EC, OC, and WSOC) is best correlated with the IL-6 biomarker. This result allows us to draw up regional maps of the inflammatory impact linked to carbonaceous particles and their emission sources. These studies will eventually lead to the implementation of emission reduction solutions to improve air quality and health.Cette thèse s'inscrit dans les objectifs scientifiques du programme DACCIWA-WP2. Il s'agit d'établir un lien entre émissions, pollution atmosphérique et effets sur la santé humaine en termes d'inflammation du système respiratoire pour des sources de combustions urbaines, typiques d'Afrique de l'Ouest : trafic, feux domestiques et feux de décharge à Abidjan (Côte d'Ivoire) et à Cotonou (Bénin) pendant les saisons sèches et humides 2015-2017. Nos résultats montrent que les concentrations particulaires observées sur l'ensemble des sites dépassent largement les recommandations de l'OMS. Le site influencé par les feux domestiques est le site le plus pollué, dominé par une fraction importante de particules ultrafines (UF) et fines (F). La comparaison des sites trafic révèle que les concentrations moyennes pour chaque classe de taille sont plus élevées d'un facteur deux à Cotonou qu'à Abidjan. La caractérisation physicochimique de ces particules (carbone organique, carbone élémentaire, carbone organique soluble, ions, poussières, éléments traces) souligne que le carbone organique et les poussières sont les deux plus importants contributeurs pour les particules de taille fine et ultrafine avec plus de carbone organique à Abidjan et de poussières à Cotonou respectivement. Des études biologiques ont été menées en parallèle afin d'évaluer la réponse pro-inflammatoire induite par les particules prélevées sur chaque site, en quantifiant la libération de la cytokine IL-6 par des cellules épithéliales bronchiques humaines. Il en résulte que les particules provenant du site feu domestique sont les plus pro-inflammatoires toutes saisons confondues alors que les fractions fines et ultrafines des particules des deux sites trafic provoquent des effets comparables non négligeables à chaque saison, le site de Cotonou se démarquant par la réactivité de sa fraction grossière, liée à la présence de poussières. Les particules F et UF des sources de combustion semblent donc avoir un impact important. Ceci est confirmé par l'analyse croisée entre les données physicochimiques et toxicologiques qui montre que la composante carbonée de l'aérosol (EC, OC, WSOC) est la mieux corrélée au biomarqueur IL-6. Ce résultat nous permet de dresser des cartes régionales d'impact inflammatoire lié aux particules carbonées et à leurs sources d'émission. Ces études permettront à terme de mettre en place des solutions de réduction des émissions pour améliorer qualité de l'air et santé

Health impact assessment of combustion aerosol for different urban sources in west Africa in the dry and wet season : physico-chemical and toxicological characterization

Cette thèse s'inscrit dans les objectifs scientifiques du programme DACCIWA-WP2. Il s'agit d'établir un lien entre émissions, pollution atmosphérique et effets sur la santé humaine en termes d'inflammation du système respiratoire pour des sources de combustions urbaines, typiques d'Afrique de l'Ouest : trafic, feux domestiques et feux de décharge à Abidjan (Côte d'Ivoire) et à Cotonou (Bénin) pendant les saisons sèches et humides 2015-2017. Nos résultats montrent que les concentrations particulaires observées sur l'ensemble des sites dépassent largement les recommandations de l'OMS. Le site influencé par les feux domestiques est le site le plus pollué, dominé par une fraction importante de particules ultrafines (UF) et fines (F). La comparaison des sites trafic révèle que les concentrations moyennes pour chaque classe de taille sont plus élevées d'un facteur deux à Cotonou qu'à Abidjan. La caractérisation physicochimique de ces particules (carbone organique, carbone élémentaire, carbone organique soluble, ions, poussières, éléments traces) souligne que le carbone organique et les poussières sont les deux plus importants contributeurs pour les particules de taille fine et ultrafine avec plus de carbone organique à Abidjan et de poussières à Cotonou respectivement. Des études biologiques ont été menées en parallèle afin d'évaluer la réponse pro-inflammatoire induite par les particules prélevées sur chaque site, en quantifiant la libération de la cytokine IL-6 par des cellules épithéliales bronchiques humaines. Il en résulte que les particules provenant du site feu domestique sont les plus pro-inflammatoires toutes saisons confondues alors que les fractions fines et ultrafines des particules des deux sites trafic provoquent des effets comparables non négligeables à chaque saison, le site de Cotonou se démarquant par la réactivité de sa fraction grossière, liée à la présence de poussières. Les particules F et UF des sources de combustion semblent donc avoir un impact important. Ceci est confirmé par l'analyse croisée entre les données physicochimiques et toxicologiques qui montre que la composante carbonée de l'aérosol (EC, OC, WSOC) est la mieux corrélée au biomarqueur IL-6. Ce résultat nous permet de dresser des cartes régionales d'impact inflammatoire lié aux particules carbonées et à leurs sources d'émission. Ces études permettront à terme de mettre en place des solutions de réduction des émissions pour améliorer qualité de l'air et santé.This thesis is in line with the scientific objectives of the DACCIWA-WP2 program. It is our responsibility to establish a link between emissions, air pollution and health impacts in terms of inflammation of the respiratory system for urban combustion sources, typical of West Africa: traffic, domestic fires and waste burning in Abidjan (Côte d'Ivoire) and Cotonou (Benin) during the dry and wet seasons 2015-2017. Our results show that the particulate concentrations observed at all sites far exceed the recommendations of WHO. The site influenced by domestic fires is the most polluted site, dominated by a significant fraction of ultrafine (UF) and fine (F) particles. The comparison of traffic sites shows that the average concentrations for each size class are twice higher in Cotonou than in Abidjan. The physicochemical characterization of these particles (organic carbon, elemental carbon, soluble organic carbon, ions, dust, trace elements) underlines that organic carbon and dust are the two most important contributors for Fand UF particles with more organic carbon in Abidjan and dust in Cotonou respectively. Parallel biological studies were conducted to characterize the pro-inflammatory response induced by particles collected for each site quantifying the release of the IL-6cytokines by human bronchial epithelial cells. As a result, particles from the domestic fire site are the most pro-inflammatory particles whatever the season, while the fine and ultra-fine fractions of particles from the two traffic sites cause significant comparable effects for each season, with the Cotonou site distinguishing itself by the reactivity of its coarse fraction, linked to the presence of dust. The F and UF particles of the combustion sources therefore seem to have a significant impact. This is confirmed by the crossed analysis between physicochemical and toxicological data, which shows that the carbonaceous aerosol component of the aerosol (EC, OC, and WSOC) is best correlated with the IL-6 biomarker. This result allows us to draw up regional maps of the inflammatory impact linked to carbonaceous particles and their emission sources. These studies will eventually lead to the implementation of emission reduction solutions to improve air quality and health

Physico-chemical characterization of urban aerosols from specific combustion sources in West Africaat Abidjan in Côte d’Ivoire and Cotonou in Benin in the frame of DACCIWA program

International audienceUrban air pollution in West Africa has yet to be well characterized. In the frame of DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) program , intensive measurement campaigns were performed in Abidjan (Côte d'Ivoire) and Cotonou (Benin), in dry (Jan-uary 2016 and 2017) and wet (July 2015 and 2016) seasons, at different sites chosen to be representative of African urban combustion sources, i.e., domestic fires (ADF), traffic (AT) and waste burning (AWB) sources in Abidjan and traffic source in Cotonou (CT). Both the size distribution of particulate matter (PM) and their chemical composition including elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSI) and trace metals were examined. Results show very high PM concentrations at all sites and a well-marked seasonality as well as a strong spatial variation. The average PM 2.5 mass concentrations during the wet season are 517.3, 104.1, 90.3, and 69.1 µg m −3 at the ADF, CT, AT, and AWB sites, respectively. In the dry season, PM 2.5 concentrations decrease to 375.7 µg m −3 at the ADF site, while they increase to 269.7, 141.3, and 175.3 µg m −3 at the CT, AT, and AWB sites, respectively. The annual PM 2.5 levels at almost all sites are significantly higher than the WHO guideline level of 10 µg m −3. As for PM mass, (EC) and (OC) concentrations are also maximal at the ADF site, accounting for up to 69 % of the total PM mass. Such a high content is mainly linked to wood burning for domestic cooking and commercial food smoking activities. Dust contributions are dominant at CT (57 %-80 %), AT (20 %-70 %), and AWB (30 %-69 %) sites and especially in the coarse and fine-particle modes at the CT site and in the coarse fraction at the AT site, which may be explained by the impact of long-range desert-dust transport and resuspended particles from the roads, in addition to anthro-pogenic sources. The contributions of WSI to the total PM mass, mainly driven by chloride, nitrate, and calcium in the fine and/or large particles, are highly variable according to the sites but remain less than 30 %. Values are generally 1-3 times higher in the wet season than in the dry season. This is due not only to anthropogenic emissions but also to nitrate formation by reaction processes and natural emissions. The concentrations of trace elements reflect well the trends in dust at the traffic and AWB sites, with a predominance Published by Copernicus Publications on behalf of the European Geosciences Union. 5328 A. J. Adon et al.: Physico-chemical characterization of urban aerosols of Al, Na, Ca, Fe, and K, keys markers of crustal dust. This study constitutes an original database that characterizes specific African combustion sources