Browsing by Author "Vallarino, J."
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Item Characterizing Air Pollution in Two Low-Income Neighborhoods in Accra, Ghana(Science of the Total Environment 402 (2-3): 217-231, 2008) Arku, R.; Vallarino, J.; Dionisio, K.L.; Wilson, J.G.; Memphill, C.; Agyei-Mensah, S.; Spengler, J.; Ezzati, M.Sub-Saharan Africa has the highest rate of urban population growth in the world, with a large number of urban residents living in low-income “slum” neighborhoods. We conducted a study for an initial assessment of the levels and spatial and/or temporal patterns of multiple pollutants in the ambient air in two low-income neighborhoods in Accra, Ghana. Over a 3-week period we measured (i) 24-hour integrated PM10 and PM2.5 mass at four roof-top fixed sites, also used for particle speciation; (ii) continuous PM10 and PM2.5 at one fixed site; and (iii) 96-hour integrated concentration of sulfur dioxide (SO2) and nitrogen dioxide (NO2) at 30 fixed sites. We also conducted seven consecutive days of mobile monitoring of PM10 and PM2.5 mass and submicron particle count. PM10 ranged from 57.9 to 93.6 μg/m3 at the four sites, with a weighted average of 71.8 μg/m3 and PM2.5 from 22.3 to 40.2 μg/m3, with an average of 27.4 μg/m3. PM2.5/PM10 ratio at the four fixed sites ranged from 0.33 to 0.43. Elemental carbon (EC) was 10–11% of PM2.5 mass at all four measurement sites; organic matter (OM) formed slightly less than 50% of PM2.5 mass. Cl, K, and S had the largest elemental contributions to PM2.5 mass, and Cl, Si, Ca, Fe, and Al to coarse particles. SO2 and NO2 concentrations were almost universally lower than the US-EPA National Ambient Air Quality Standards (NAAQS), with virtually no variation across sites. There is evidence for the contributions from biomass and traffic sources, and from geological and marine non-combustion sources to particle pollution. The implications of the results for future urban air pollution monitoring and measurement in developing countries are discussed.Item Chemical characterization and source apportionment of household fine particulate matter in rural, peri-urban, and urban West Africa(Environmental Science and Technology, 2014) Zhou, Z.; Dionisio, K.L.; Verissimo, T.G.; Kerr, A.S.; Coull, B.; Howie, S.; Arku, R.E.; Koutrakis, P.; Renner, J.D.; Fornace, K.; Hughes, A.F.; Vallarino, J.; Agyei-Mensah, S.; Ezzati, M.Household air pollution in sub-Saharan Africa and other developing regions is an important cause of disease burden. Little is known about the chemical composition and sources of household air pollution in sub-Saharan Africa, and how they differ between rural and urban homes. We analyzed the chemical composition and sources of fine particles (PM2.5) in household cooking areas of multiple neighborhoods in Accra, Ghana, and in peri-urban (Banjul) and rural (Basse) areas in The Gambia. In Accra, biomass burning accounted for 39-62% of total PM2.5 mass in the cooking area in different neighborhoods; the absolute contributions were 10-45 μg/m 3. Road dust and vehicle emissions comprised 12-33% of PM 2.5 mass. Solid waste burning was also a significant contributor to household PM2.5 in a low-income neighborhood but not for those living in better-off areas. In Banjul and Basse, biomass burning was the single dominant source of cooking-area PM2.5, accounting for 74-87% of its total mass; the relative and absolute contributions of biomass smoke to PM 2.5 mass were larger in households that used firewood than in those using charcoal, reaching as high as 463 μg/m3 in Basse homes that used firewood for cooking. Our findings demonstrate the need for policies that enhance access to cleaner fuels in both rural and urban areas, and for controlling traffic emissions in cities in sub-Saharan Africa. © 2013 American Chemical Society.Item Chemical composition and sources of particle pollution in affluent and poor neighborhoods of Accra, Ghana(Environmental Research Letters, 2013-12) Zhou, Z.; Dionisio, K.L.; Verissimo, T.G.; Kerr, A.S.; Coull, B.; Arku, R.E.; Koutrakis, P.; Spengler, J.D.; Hughes, A.F.; Vallarino, J.; Agyei-Mensah, S.; Ezzati, M.The highest levels of air pollution in the world now occur in developing country cities, where air pollution sources differ from high-income countries. We analyzed particulate matter (PM) chemical composition and estimated the contributions of various sources to particle pollution in poor and affluent neighborhoods of Accra, Ghana. Elements from earth's crust were most abundant during the seasonal Harmattan period between late December and late January when Saharan dust is carried to coastal West Africa. During Harmattan, crustal particles accounted for 55 μg m-3 (37%) of fine particle (PM 2.5) mass and 128 μg m-3 (42%) of PM10 mass. Outside Harmattan, biomass combustion, which was associated with higher black carbon, potassium, and sulfur, accounted for between 10.6 and 21.3 μg m -3 of fine particle mass in different neighborhoods, with its contribution largest in the poorest neighborhood. Other sources were sea salt, vehicle emissions, tire and brake wear, road dust, and solid waste burning. Reducing air pollution in African cities requires policies related to energy, transportation and urban planning, and forestry and agriculture, with explicit attention to impacts of each strategy in poor communities. Such cross-sectoral integration requires emphasis on urban environment and urban poverty in the post-2015 Development Agenda. © 2013 IOP Publishing Ltd.Item Household and community poverty, biomass use, and air pollution in Accra, Ghana(Proceedings of the National Academy of the United States of America, 2011-07) Zhoua, Z.; Dionisio, K.L.; Arku, R.E.; Quaye, A.; Hughes, A.F.; Vallarino, J.; Spengler, J.D.; Hill, A.; Agyei-Mensah, S.; Ezzati, M.Many urban households in developing countries use biomass fuels for cooking. The proportion of household biomass use varies among neighborhoods, and is generally higher in low socioeconomic status (SES) communities. Little is known of how household air pollution varies by SES and how it is affected by biomass fuels and traffic sources in developing country cities. In four neighborhoods in Accra, Ghana, we collected and analyzed geo-referenced data on household and community particulate matter (PM) pollution, SES, fuel use for domestic and small-commercial cooking, housing characteristics, and distance to major roads. Cooking area PM was lowest in the high-SES neighborhood, with geometric means of 25 (95% confidence interval, 21–29) and 28 (23–33) μg/m3 for fine and coarse PM (PM2.5 and PM2.5–10), respectively; it was highest in two low-SES slums, with geometric means reaching 71 (62–80) and 131 (114–150) μg/m3 for fine and coarse PM. After adjustment for other factors, living in a community where all households use biomass fuels would be associated with 1.5- to 2.7-times PM levels in models with and without adjustment for ambient PM. Community biomass use had a stronger association with household PM than household’s own fuel choice in crude and adjusted estimates. Lack of regular physical access to clean fuels is an obstacle to fuel switching in low-income neighborhoods and should be addressed through equitable energy infrastructure.Item Household and community poverty, biomass use, and air pollution in Accra, Ghana(National Academy of Science of the Unites States of America, 2011-06) Zhoua, Z.; Dionisio, K.L.; Arku, R.E.; Quaye, A.; Hughes, A.F.; Vallarino, J.; Spengler, J.D.; Hill, A.; Agyei-Mensah, S.; Ezzati, M.Many urban households in developing countries use biomass fuels for cooking. The proportion of household biomass use varies among neighborhoods, and is generally higher in low socioeconomic status (SES) communities. Little is known of how household air pollution varies by SES and how it is affected by biomass fuels and traffic sources in developing country cities. In four neighborhoods in Accra, Ghana, we collected and analyzed geo-referenced data on household and community particulate matter (PM) pollution, SES, fuel use for domestic and small-commercial cooking, housing characteristics, and distance to major roads. Cooking area PM was lowest in the high-SES neighborhood, with geometric means of 25 (95% confidence interval, 21–29) and 28 (23–33) μg/m3 for fine and coarse PM (PM2.5 and PM2.5–10), respectively; it was highest in two low-SES slums, with geometric means reaching 71 (62–80) and 131 (114–150) μg/m3 for fine and coarse PM. After adjustment for other factors, living in a community where all households use biomass fuels would be associated with 1.5- to 2.7-times PM levels in models with and without adjustment for ambient PM. Community biomass use had a stronger association with household PM than household’s own fuel choice in crude and adjusted estimates. Lack of regular physical access to clean fuels is an obstacle to fuel switching in low-income neighborhoods and should be addressed through equitable energy infrastructure.Item particle Pollution in Accra Neighbourhoods: Spatial, Temporal, and Socioeconomic Patterns(Environmental Science and Technology, 2010) Dionisio, K. L.; Arku, R. E.; Hughes, A. F.; Vallarino, J.; Carmichael, H.; Friedman, A. B.; Agyei-Mensah, S.; Spengler, J. D.; Ezzati, M.This study examined the spatial, socioeconomic status (SES), and temporal patterns of ambient air pollution in Accra, Ghana. Over 22 months, integrated and continuous rooftop particulate matter (PM) monitors were placed at a total of 11 residential or roadside monitoring sites in four neighborhoods of varying SES and biomass fuel use. PM concentrations were highest in late December and January, due to dust blown from the Sahara. Excluding this period, annual PM2.5 ranged from 39 to 53 μg/m3 at roadside sites and 30 to 70 μg/m3 at residential sites; mean annual PM10 ranged from 80 to 108 μg/m3 at roadside sites and 57 to 106 μg/m3 at residential sites. The low-income and densely populated neighborhood of Jamestown/Ushertown had the single highest residential PM concentration. There was less difference across traffic sites. Daily PM increased at all sites at daybreak, followed by a mid-day peak at some sites, and a more spread-out evening peak at all sites. Average carbon monoxide concentrations at different sites and seasons ranged from 7 to 55 ppm, and were generally lower at residential sites than at traffic sites. The results show that PM in these four neighborhoods is substantially higher than the WHO Air Quality Guidelines and in some cases even higher than the WHO Interim Target 1, with the highest pollution in the poorest neighborhood.Item Personal particulate matter exposures and locations of students in four neighborhoods in Accra, Ghana.(NCBI, 2015) Arku, R.E.; Dionisio, K.L.; Hughes, A.F.; Vallarino, J.; Spengler, J.D.; Castro, M.C.; Agyei-Mensah, S.; Ezzati, M.Air pollution exposure and places where the exposures occur may differ in cities in the developing world compared with high-income countries. Our aim was to measure personal fine particulate matter (PM2.5) exposure of students in neighborhoods of varying socioeconomic status in Accra, Ghana, and to quantify the main predictors of exposure. We measured 24-hour PM2.5 exposure of 56 students from eight schools in four neighborhoods. PM2.5 was measured both gravimetrically and continuously, with time-matched global positioning system coordinates. We collected data on determinants of exposure, such as distances of homes and schools from main roads and fuel used for cooking at their home or in the area of residence/school. The association of PM2.5 exposure with sources was estimated using linear mixed-effects models. Personal PM2.5 exposures ranged from less than 10 μg/m(3) to more than 150 μg/m(3) (mean 56 μg/m(3)). Girls had higher exposure than boys (67 vs 44 μg/m(3); P-value=0.001). Exposure was inversely associated with distance of home or school to main roads, but the associations were not statistically significant in the multivariate model. Use of biomass fuels in the area where the school was located was also associated with higher exposure, as was household's own biomass use. Paved schoolyard surface was associated with lower exposure. School locations in relation to major roads, materials of school ground surfaces, and biomass use in the area around schools may be important determinants of air pollution exposure.Item Personal particulate matter exposures and locations of students in four neighborhoods in Accra, Ghana.(Journal of Exposure Science and Environmental Epidemiology, 2015-11) Arku, R.E.; Dionisio, K.L.; Hughes, A.F.; Vallarino, J.; Spengler, J.D.; Castro, M.C.; Agyei-Mensah, S.; Ezzati, M.Air pollution exposure and places where the exposures occur may differ in cities in the developing world compared with high-income countries. Our aim was to measure personal fine particulate matter (PM2.5) exposure of students in neighborhoods of varying socioeconomic status in Accra, Ghana, and to quantify the main predictors of exposure. We measured 24-hour PM2.5 exposure of 56 students from eight schools in four neighborhoods. PM2.5 was measured both gravimetrically and continuously, with time-matched global positioning system coordinates. We collected data on determinants of exposure, such as distances of homes and schools from main roads and fuel used for cooking at their home or in the area of residence/school. The association of PM2.5 exposure with sources was estimated using linear mixed-effects models. Personal PM2.5 exposures ranged from less than 10 μg/m3 to more than 150 μg/m3 (mean 56 μg/m3). Girls had higher exposure than boys (67 vs 44 μg/m3; P-value=0.001). Exposure was inversely associated with distance of home or school to main roads, but the associations were not statistically significant in the multivariate model. Use of biomass fuels in the area where the school was located was also associated with higher exposure, as was household’s own biomass use. Paved schoolyard surface was associated with lower exposure. School locations in relation to major roads, materials of school ground surfaces, and biomass use in the area around schools may be important determinants of air pollution exposure.Item Spatial and temporal patterns of particulate matter sources and pollution in four communities in Accra, Ghana(Elsevier, 2012) Rooney, M.S.; Arku, R.E.; Dionisio, K.L.; Paciorek, C.; Friedman, A.B.; Carmichael, H.; Zhoua, Z.; Hughes, A.F.; Vallarino, J.; Agyei-Mensah, S.; Spengler, J.D.; Ezzati, M.Sources of air pollution in developing country cities include transportation and industrial pollution, biomass fuel use, and re-suspended dust from unpaved roads. We examined the spatial patterns of particulate matter (PM) and its sources in four neighborhoods of varying socioeconomic status (SES) in Accra. PM data were from 1 week of morning and afternoon mobile and stationary air pollution measurements in each of the study neighborhoods. PM2.5 and PM10 were measured continuously, with matched GPS coordinates. Data on biomass fuel use were from the Ghana 2000 population and housing census and from a census of wood and charcoal stoves along the mobile monitoring paths. We analyzed the associations of PM with sources using a mixed-effects regression model accounting for temporal and spatial autocorrelation. After adjusting for other factors, the density of wood stoves, fish smoking, and trash burning along the mobile monitoring path as well as road capacity and surface were associated with higher PM2.5. Road capacity and road surface variables were also associated with PM10, but the association with biomass sources was weak or absent. While wood stoves and fish smoking were significant sources of air pollution, addressing them would require financial and physical access to alternative fuels for low-income households and communities.Item Spatial-temporal patterns of ambient fine particulate matter (PM2.5) and black carbon (BC) pollution in Accra(IOP publishing ltd, 2021) Alli, A.S.; Clark, S.N.; Hughes, A.; Nimo, J.; Bedford-Moses, J.; Baah, S.; Wang, J.; Vallarino, J.; Agyemang, E.; Barratt, B.; Beddows, A.; Kelly, F.; Owusu, G.; Baumgartne, J.; Brauer, M.; Ezzati, M.; Agyei-Mensah, S.; Arku, R.E.Sub-Saharan Africa (SSA) is rapidly urbanizing, and ambient air pollution has emerged as a major environmental health concern in growing cities. Yet, effective air quality management is hindered by limited data. We deployed robust, low-cost and low-power devices in a large-scale measurement campaign and characterized within-city variations in fine particulate matter (PM2.5) and black carbon (BC) pollution in Accra, Ghana. Between April 2019 and June 2020, we measured weekly gravimetric (filter-based) and minute-by-minute PM2.5 concentrations at 146 unique locations, comprising of 10 fixed (∼1 year) and 136 rotating (7 day) sites covering a range of land-use and source influences. Filters were weighed for mass, and light absorbance (10−5m−1 ) of the filters was used as proxy for BC concentration. Year-long data at four fixed sites that were monitored in a previous study (2006–2007) were compared to assess changes in PM2.5 concentrations. The mean annual PM2.5 across the fixed sites ranged from 26 µg m−3 at a peri-urban site to 43 µg m−3 at a commercial, business, and industrial (CBI) site. CBI areas had the highest PM2.5 levels (mean: 37 µg m−3 ), followed by high-density residential neighborhoods (mean: 36 µg m−3 ), while peri-urban areas recorded the lowest (mean: 26 µg m−3 ). Both PM2.5 and BC levels were highest during the dry dusty Harmattan period (mean PM2.5: 89 µg m−3 ) compared to non-Harmattan season (mean PM2.5: 23 µg m−3 ). PM2.5 at all sites peaked at dawn and dusk, coinciding with morning and evening heavy traffic. We found about a 50% reduction (71 vs 37 µg m−3 ) in mean annual PM2.5 concentrations when compared to measurements in 2006–2007 in Accra. Ambient PM2.5 concentrations in Accra may have plateaued at levels lower than those seen in large Asian megacities. However, levels are still 2- to 4-fold higher than the WHO guideline. Effective and equitable policies are needed to reduce pollution levels and protect public health.Item Within Neighborhood Patterns and Sources of particle Pollution: Mobile Monitoring and GIS Analysis in Four Accra Communities(Environmental Health Perspectives, 2010) Dionisio, K. L.; Rooney, M. S.; Arku, R. E.; Friedman, A. B.; Paciorek, C.; Hughes, A. F.; Vallarino, J.; Carmichael, H.; Agyei-Mensah, S.; Spengler, J. D.; Ezzati, M.Sources of air pollution in developing country cities include transportation and industrial pollution, biomass and coal fuel use, and resuspended dust from unpaved roads. Our goal was to understand within-neighborhood spatial variability of particulate mat¬ter (PM) in communities of varying socioeconomic status (SES) in Accra, Ghana, and to quantify the effects of nearby sources on local PM concentration.We conducted 1 week of morning and afternoon mobile and stationary air pollution measurements in four study neighborhoods. PM with aerodynamic diameters ≤ 2.5 μm (PM2.5) and ≤ 10 μm (PM10) was measured continuously, with matched global positioning system coordinates; detailed data on local sources were collected at periodic stops. The effects of nearby sources on local PM were estimated using linear mixed-effects models. In our measurement campaign, the geometric means of PM2.5 and PM10 along the mobile monitoring path were 21 and 49 μg/m3, respectively, in the neighborhood with highest SES and 39 and 96 μg/m3, respectively, in the neighborhood with lowest SES and highest population den¬sity. PM2.5 and PM10 were as high as 200 and 400 μg/m3, respectively, in some segments of the path. After adjusting for other factors, the factors that had the largest effects on local PM pollution were nearby wood and charcoal stoves, congested and heavy traffic, loose dirt road surface, and trash burning. Biomass fuels, transportation, and unpaved roads may be important determinants of local PM variation in Accra neighborhoods. If confirmed by additional or supporting data, the results demonstrate the need for effective and equitable interventions and policies that reduce the impacts of traffic and biomass pollution.