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Alli AS, Clark SN, Hughes A, Nimo J, Bedford-Moses J, Baah S, Wang J, Vallarino J, Agyemang E, Barratt B, Beddows A, Kelly F, Owusu G, Baumgartner J, Brauer M, Ezzati M, Agyei-Mensah S, Arku RE. Spatial-temporal patterns of ambient fine particulate matter (PM 2.5) and black carbon (BC) pollution in Accra. ENVIRONMENTAL RESEARCH LETTERS : ERL [WEB SITE] 2021; 16:074013. [PMID: 34239599 PMCID: PMC8227509 DOI: 10.1088/1748-9326/ac074a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 05/06/2023]
Abstract
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.
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Affiliation(s)
- Abosede S Alli
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, United States of America
| | - Sierra N Clark
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London, United Kingdom
- MRC Center for Environment and Health, Imperial College London, London, United Kingdom
| | - Allison Hughes
- Department of Physics, University of Ghana, Legon, Ghana
| | - James Nimo
- Department of Physics, University of Ghana, Legon, Ghana
| | | | - Solomon Baah
- Department of Physics, University of Ghana, Legon, Ghana
| | - Jiayuan Wang
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, United States of America
| | - Jose Vallarino
- Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - Ernest Agyemang
- Department of Geography and Resource Development, University of Ghana, Legon, Ghana
| | - Benjamin Barratt
- MRC Center for Environment and Health, Imperial College London, London, United Kingdom
- NIHR HPRU in Environmental Exposures and Health, Imperial College London, London, United Kingdom
| | - Andrew Beddows
- MRC Center for Environment and Health, Imperial College London, London, United Kingdom
- NIHR HPRU in Environmental Exposures and Health, Imperial College London, London, United Kingdom
| | - Frank Kelly
- MRC Center for Environment and Health, Imperial College London, London, United Kingdom
- NIHR HPRU in Environmental Exposures and Health, Imperial College London, London, United Kingdom
| | - George Owusu
- Department of Geography and Resource Development, University of Ghana, Legon, Ghana
| | - Jill Baumgartner
- Institute for Health and Social Policy, McGill University, Montreal, Canada
- Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada
| | - Michael Brauer
- School of Population and Public Health, The University of British Columbia, Vancouver, Canada
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, United States of America
| | - Majid Ezzati
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London, United Kingdom
- MRC Center for Environment and Health, Imperial College London, London, United Kingdom
- Regional Institute for Population Studies, University of Ghana, Legon, Ghana
| | - Samuel Agyei-Mensah
- Department of Geography and Resource Development, University of Ghana, Legon, Ghana
| | - Raphael E Arku
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, United States of America
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