1
|
Wang J, Alli AS, Clark SN, Ezzati M, Brauer M, Hughes AF, Nimo J, Moses JB, Baah S, Nathvani R, D V, Agyei-Mensah S, Baumgartner J, Bennett JE, Arku RE. Inequalities in urban air pollution in sub-Saharan Africa: an empirical modeling of ambient NO and NO 2 concentrations in Accra, Ghana. ENVIRONMENTAL RESEARCH LETTERS : ERL [WEB SITE] 2024; 19:034036. [PMID: 38419692 PMCID: PMC10897512 DOI: 10.1088/1748-9326/ad2892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 02/04/2024] [Accepted: 02/12/2024] [Indexed: 03/02/2024]
Abstract
Road traffic has become the leading source of air pollution in fast-growing sub-Saharan African cities. Yet, there is a dearth of robust city-wide data for understanding space-time variations and inequalities in combustion related emissions and exposures. We combined nitrogen dioxide (NO2) and nitric oxide (NO) measurement data from 134 locations in the Greater Accra Metropolitan Area (GAMA), with geographical, meteorological, and population factors in spatio-temporal mixed effects models to predict NO2 and NO concentrations at fine spatial (50 m) and temporal (weekly) resolution over the entire GAMA. Model performance was evaluated with 10-fold cross-validation (CV), and predictions were summarized as annual and seasonal (dusty [Harmattan] and rainy [non-Harmattan]) mean concentrations. The predictions were used to examine population distributions of, and socioeconomic inequalities in, exposure at the census enumeration area (EA) level. The models explained 88% and 79% of the spatiotemporal variability in NO2 and NO concentrations, respectively. The mean predicted annual, non-Harmattan and Harmattan NO2 levels were 37 (range: 1-189), 28 (range: 1-170) and 50 (range: 1-195) µg m-3, respectively. Unlike NO2, NO concentrations were highest in the non-Harmattan season (41 [range: 31-521] µg m-3). Road traffic was the dominant factor for both pollutants, but NO2 had higher spatial heterogeneity than NO. For both pollutants, the levels were substantially higher in the city core, where the entire population (100%) was exposed to annual NO2 levels exceeding the World Health Organization (WHO) guideline of 10 µg m-3. Significant disparities in NO2 concentrations existed across socioeconomic gradients, with residents in the poorest communities exposed to levels about 15 µg m-3 higher compared with the wealthiest (p < 0.001). The results showed the important role of road traffic emissions in air pollution concentrations in the GAMA, which has major implications for the health of the city's poorest residents. These data could support climate and health impact assessments as well as policy evaluations in the city.
Collapse
Affiliation(s)
- Jiayuan Wang
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, United States of America
| | - 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, London, United Kingdom
- MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, United Kingdom
| | - Majid Ezzati
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, United Kingdom
- MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, United Kingdom
- Regional Institute for Population Studies, University of Ghana, Accra, Ghana
- Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, United Kingdom
| | - Michael Brauer
- School of Population and Public Health, The University of British Columbia, Vancouver, Canada
| | | | - James Nimo
- Department of Physics, University of Ghana, Accra, Ghana
| | | | - Solomon Baah
- Department of Physics, University of Ghana, Accra, Ghana
| | - Ricky Nathvani
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, United Kingdom
- MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, United Kingdom
| | - Vishwanath D
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, United Kingdom
- MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, United Kingdom
| | - Samuel Agyei-Mensah
- Department of Geography and Resource Development, University of Ghana, Accra, Ghana
- Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom
| | - Jill Baumgartner
- Institute for Health and Social Policy, McGill University, Montreal, Canada
- Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada
| | - James E Bennett
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, United Kingdom
- MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, United Kingdom
| | - Raphael E Arku
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, United States of America
| |
Collapse
|
2
|
Nathvani R, D V, Clark SN, Alli AS, Muller E, Coste H, Bennett JE, Nimo J, Moses JB, Baah S, Hughes A, Suel E, Metzler AB, Rashid T, Brauer M, Baumgartner J, Owusu G, Agyei-Mensah S, Arku RE, Ezzati M. Beyond here and now: Evaluating pollution estimation across space and time from street view images with deep learning. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 903:166168. [PMID: 37586538 PMCID: PMC7615099 DOI: 10.1016/j.scitotenv.2023.166168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 08/07/2023] [Accepted: 08/07/2023] [Indexed: 08/18/2023]
Abstract
Advances in computer vision, driven by deep learning, allows for the inference of environmental pollution and its potential sources from images. The spatial and temporal generalisability of image-based pollution models is crucial in their real-world application, but is currently understudied, particularly in low-income countries where infrastructure for measuring the complex patterns of pollution is limited and modelling may therefore provide the most utility. We employed convolutional neural networks (CNNs) for two complementary classification models, in both an end-to-end approach and as an interpretable feature extractor (object detection), to estimate spatially and temporally resolved fine particulate matter (PM2.5) and noise levels in Accra, Ghana. Data used for training the models were from a unique dataset of over 1.6 million images collected over 15 months at 145 representative locations across the city, paired with air and noise measurements. Both end-to-end CNN and object-based approaches surpassed null model benchmarks for predicting PM2.5 and noise at single locations, but performance deteriorated when applied to other locations. Model accuracy diminished when tested on images from locations unseen during training, but improved by sampling a greater number of locations during model training, even if the total quantity of data was reduced. The end-to-end models used characteristics of images associated with atmospheric visibility for predicting PM2.5, and specific objects such as vehicles and people for noise. The results demonstrate the potential and challenges of image-based, spatiotemporal air pollution and noise estimation, and that robust, environmental modelling with images requires integration with traditional sensor networks.
Collapse
Affiliation(s)
- Ricky Nathvani
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK.
| | - Vishwanath D
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - Sierra N Clark
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - Abosede S Alli
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - Emily Muller
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - Henri Coste
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - James E Bennett
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - James Nimo
- Department of Physics, University of Ghana, Accra, Ghana
| | | | - Solomon Baah
- Department of Physics, University of Ghana, Accra, Ghana
| | - Allison Hughes
- Department of Physics, University of Ghana, Accra, Ghana
| | - Esra Suel
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK; Centre for Advanced Spatial Analysis, University College London, London, UK
| | - Antje Barbara Metzler
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - Theo Rashid
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - Michael Brauer
- School of Population and Public Health, University of British Columbia, Vancouver, Canada
| | - Jill Baumgartner
- Institute for Health and Social Policy, McGill University, Montreal, Canada; Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada
| | - George Owusu
- Institute of Statistical, Social & Economic Research, University of Ghana, Accra, Ghana
| | - Samuel Agyei-Mensah
- Department of Geography and Resource Development, University of Ghana, Accra, Ghana
| | - Raphael E Arku
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - Majid Ezzati
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK; Regional Institute for Population Studies, University of Ghana, Accra, Ghana
| |
Collapse
|
3
|
Metzler AB, Nathvani R, Sharmanska V, Bai W, Muller E, Moulds S, Agyei-Asabere C, Adjei-Boadi D, Kyere-Gyeabour E, Tetteh JD, Owusu G, Agyei-Mensah S, Baumgartner J, Robinson BE, Arku RE, Ezzati M. Phenotyping urban built and natural environments with high-resolution satellite images and unsupervised deep learning. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 893:164794. [PMID: 37315611 PMCID: PMC7615085 DOI: 10.1016/j.scitotenv.2023.164794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/05/2023] [Accepted: 06/08/2023] [Indexed: 06/16/2023]
Abstract
Cities in the developing world are expanding rapidly, and undergoing changes to their roads, buildings, vegetation, and other land use characteristics. Timely data are needed to ensure that urban change enhances health, wellbeing and sustainability. We present and evaluate a novel unsupervised deep clustering method to classify and characterise the complex and multidimensional built and natural environments of cities into interpretable clusters using high-resolution satellite images. We applied our approach to a high-resolution (0.3 m/pixel) satellite image of Accra, Ghana, one of the fastest growing cities in sub-Saharan Africa, and contextualised the results with demographic and environmental data that were not used for clustering. We show that clusters obtained solely from images capture distinct interpretable phenotypes of the urban natural (vegetation and water) and built (building count, size, density, and orientation; length and arrangement of roads) environment, and population, either as a unique defining characteristic (e.g., bodies of water or dense vegetation) or in combination (e.g., buildings surrounded by vegetation or sparsely populated areas intermixed with roads). Clusters that were based on a single defining characteristic were robust to the spatial scale of analysis and the choice of cluster number, whereas those based on a combination of characteristics changed based on scale and number of clusters. The results demonstrate that satellite data and unsupervised deep learning provide a cost-effective, interpretable and scalable approach for real-time tracking of sustainable urban development, especially where traditional environmental and demographic data are limited and infrequent.
Collapse
Affiliation(s)
- A Barbara Metzler
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, Imperial College London, London, UK
| | - Ricky Nathvani
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, Imperial College London, London, UK
| | - Viktoriia Sharmanska
- Department of Informatics, University of Sussex, UK; Department of Computing, Imperial College London, London, UK
| | - Wenjia Bai
- Department of Computing, Imperial College London, London, UK; Department of Brain Sciences, Imperial College London, London, UK
| | - Emily Muller
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, Imperial College London, London, UK
| | - Simon Moulds
- School of Geography and the Environment, University of Oxford, UK
| | | | - Dina Adjei-Boadi
- Department of Geography and Resource Development, University of Ghana, Legon, Accra, Ghana
| | - Elvis Kyere-Gyeabour
- Department of Geography and Resource Development, University of Ghana, Legon, Accra, Ghana
| | - Jacob Doku Tetteh
- Department of Geography and Resource Development, University of Ghana, Legon, Accra, Ghana
| | - George Owusu
- Institute of Statistical, Social & Economic Research, University of Ghana, Accra, Ghana
| | - Samuel Agyei-Mensah
- Department of Geography and Resource Development, University of Ghana, Legon, Accra, Ghana
| | - Jill Baumgartner
- Department of Epidemiology and Biostatistics, McGill University, Montreal, Québec, Canada; Department of Equity, Ethics and Policy, McGill University, Montreal, Québec, Canada
| | - Brian E Robinson
- Department of Geography, McGill University, Montreal, Québec, Canada
| | - Raphael E Arku
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - Majid Ezzati
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, Imperial College London, London, UK; Regional Institute for Population Studies, University of Ghana, Accra, Ghana; Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK.
| |
Collapse
|
4
|
Gemmell E, Adjei-Boadi D, Sarkar A, Shoari N, White K, Zdero S, Kassem H, Pujara T, Brauer M. "In small places, close to home": Urban environmental impacts on child rights across four global cities. Health Place 2023; 83:103081. [PMID: 37506630 PMCID: PMC7615291 DOI: 10.1016/j.healthplace.2023.103081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 06/03/2023] [Accepted: 06/28/2023] [Indexed: 07/30/2023]
Abstract
Urban environments influence child behaviours, exposures and experiences and may affect health, development, achievement and realization of fundamental human rights. We examined the status of eleven UN Convention on the Rights of the Child articles, in a multi-case study across four global cities. Within all study cities, children experienced unequal exposure to urban environmental risks and amenities. Many violations of child rights are related to car-based transportation systems and further challenged by pressures on urban systems from rapid population increases in the context of climate change. A child rights framework provides principles for a collective, multi-sectoral re-imagination of urban environments that support the human rights of all citizens.
Collapse
Affiliation(s)
- Emily Gemmell
- School of Population and Public Health, University of British Columbia, Vancouver, 2206 West Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Dina Adjei-Boadi
- Department of Geography and Resource Development, University of Ghana, MR28+9MQ, Doutor J.B. Danquah Avenue, Accra, Ghana.
| | - Asesh Sarkar
- Department of Architecture and Planning, Indian Institute of Technology, Haridwar Highway, Roorkee, Uttarakhand, 247667, India.
| | - Niloofar Shoari
- MRC Centre for Environment & Health, Department of Epidemiology and Biostatistics, Imperial College London, St Mary's Campus, Norfolk Place, London, W2 1PG, United Kingdom.
| | - Katherine White
- School of Population and Public Health, University of British Columbia, Vancouver, 2206 West Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Svetlana Zdero
- School of Population and Public Health, University of British Columbia, Vancouver, 2206 West Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Hallah Kassem
- School of Population and Public Health, University of British Columbia, Vancouver, 2206 West Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Tina Pujara
- Department of Architecture and Planning, Indian Institute of Technology, Haridwar Highway, Roorkee, Uttarakhand, 247667, India.
| | - Michael Brauer
- School of Population and Public Health, University of British Columbia, Vancouver, 2206 West Mall, Vancouver, BC, V6T 1Z4, Canada; Institute for Health Metrics and Evaluation, Population Health Building, Hans Rosling Center, 3980 15th Ave. NE, Seattle, WA, 98195, USA.
| |
Collapse
|
5
|
Raheja G, Nimo J, Appoh EKE, Essien B, Sunu M, Nyante J, Amegah M, Quansah R, Arku RE, Penn SL, Giordano MR, Zheng Z, Jack D, Chillrud S, Amegah K, Subramanian R, Pinder R, Appah-Sampong E, Tetteh EN, Borketey MA, Hughes AF, Westervelt DM. Low-Cost Sensor Performance Intercomparison, Correction Factor Development, and 2+ Years of Ambient PM 2.5 Monitoring in Accra, Ghana. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:10708-10720. [PMID: 37437161 PMCID: PMC10373484 DOI: 10.1021/acs.est.2c09264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 07/14/2023]
Abstract
Particulate matter air pollution is a leading cause of global mortality, particularly in Asia and Africa. Addressing the high and wide-ranging air pollution levels requires ambient monitoring, but many low- and middle-income countries (LMICs) remain scarcely monitored. To address these data gaps, recent studies have utilized low-cost sensors. These sensors have varied performance, and little literature exists about sensor intercomparison in Africa. By colocating 2 QuantAQ Modulair-PM, 2 PurpleAir PA-II SD, and 16 Clarity Node-S Generation II monitors with a reference-grade Teledyne monitor in Accra, Ghana, we present the first intercomparisons of different brands of low-cost sensors in Africa, demonstrating that each type of low-cost sensor PM2.5 is strongly correlated with reference PM2.5, but biased high for ambient mixture of sources found in Accra. When compared to a reference monitor, the QuantAQ Modulair-PM has the lowest mean absolute error at 3.04 μg/m3, followed by PurpleAir PA-II (4.54 μg/m3) and Clarity Node-S (13.68 μg/m3). We also compare the usage of 4 statistical or machine learning models (Multiple Linear Regression, Random Forest, Gaussian Mixture Regression, and XGBoost) to correct low-cost sensors data, and find that XGBoost performs the best in testing (R2: 0.97, 0.94, 0.96; mean absolute error: 0.56, 0.80, and 0.68 μg/m3 for PurpleAir PA-II, Clarity Node-S, and Modulair-PM, respectively), but tree-based models do not perform well when correcting data outside the range of the colocation training. Therefore, we used Gaussian Mixture Regression to correct data from the network of 17 Clarity Node-S monitors deployed around Accra, Ghana, from 2018 to 2021. We find that the network daily average PM2.5 concentration in Accra is 23.4 μg/m3, which is 1.6 times the World Health Organization Daily PM2.5 guideline of 15 μg/m3. While this level is lower than those seen in some larger African cities (such as Kinshasa, Democratic Republic of the Congo), mitigation strategies should be developed soon to prevent further impairment to air quality as Accra, and Ghana as a whole, rapidly grow.
Collapse
Affiliation(s)
- Garima Raheja
- Department
of Earth and Environmental Sciences, Columbia
University, New York, New York 10027, United States
- Lamont-Doherty
Earth Observatory of Columbia University, Palisades, New York 10964, United States
| | - James Nimo
- Department
of Physics, University of Ghana, Legon, Ghana, Ghana
- African
Institute of Mathematical Sciences, Kigali, Rwanda
| | | | | | - Maxwell Sunu
- Ghana
Environmental Protection Agency, Accra, Ghana
| | - John Nyante
- Ghana
Environmental Protection Agency, Accra, Ghana
| | | | | | - Raphael E. Arku
- Department
of Environmental Health Sciences, School of Public Health and Health
Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Stefani L. Penn
- Industrial
Economics, Inc, Cambridge, Massachusetts 02140, United States
| | - Michael R. Giordano
- Univ
Paris Est Creteil, CNRS UMS 3563, Ecole Nationale des Ponts et Chaussés,
Université de Paris, OSU-EFLUVE—Observatoire Sciences
de L’Univers-Envelopes Fluides de La Ville à L’Exobiologie, F-94010 Créteil, France
| | - Zhonghua Zheng
- Department
of Earth and Environmental Sciences, The
University of Manchester, Manchester M13 9PL, U.K.
| | - Darby Jack
- Department of Environmental Health Sciences, Mailman
School of Public
Health, Columbia University, New York, New York 10032, United States
| | - Steven Chillrud
- Department of Environmental Health Sciences, Mailman
School of Public
Health, Columbia University, New York, New York 10032, United States
| | | | - R. Subramanian
- Univ
Paris Est Creteil, CNRS UMS 3563, Ecole Nationale des Ponts et Chaussés,
Université de Paris, OSU-EFLUVE—Observatoire Sciences
de L’Univers-Envelopes Fluides de La Ville à L’Exobiologie, F-94010 Créteil, France
- Kigali Collaborative
Research Centre, Kigali, Rwanda
| | - Robert Pinder
- Environmental Protection Agency, Raleigh, North Carolina 27709, United States
| | | | | | | | | | - Daniel M. Westervelt
- Lamont-Doherty
Earth Observatory of Columbia University, Palisades, New York 10964, United States
- NASA Goddard Institute for Space Science, New York, New York 10025, United States
| |
Collapse
|
6
|
Alli AS, Clark SN, Wang J, Bennett J, Hughes AF, Ezzati M, Brauer M, Nimo J, Bedford-Moses J, Baah S, Cavanaugh A, Agyei-Mensah S, Owusu G, Baumgartner J, Arku RE. High-resolution patterns and inequalities in ambient fine particle mass (PM 2.5) and black carbon (BC) in the Greater Accra Metropolis, Ghana. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 875:162582. [PMID: 36870487 PMCID: PMC10131145 DOI: 10.1016/j.scitotenv.2023.162582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 02/06/2023] [Accepted: 02/27/2023] [Indexed: 06/02/2023]
Abstract
Growing cities in sub-Saharan Africa (SSA) experience high levels of ambient air pollution. However, sparse long-term city-wide air pollution exposure data limits policy mitigation efforts and assessment of the health and climate effects. In the first study of its kind in West Africa, we developed high resolution spatiotemporal land use regression (LUR) models to map fine particulate matter (PM2.5) and black carbon (BC) concentrations in the Greater Accra Metropolitan Area (GAMA), one of the fastest sprawling metropolises in SSA. We conducted a one-year measurement campaign covering 146 sites and combined these data with geospatial and meteorological predictors to develop separate Harmattan and non-Harmattan season PM2.5 and BC models at 100 m resolution. The final models were selected with a forward stepwise procedure and performance was evaluated with 10-fold cross-validation. Model predictions were overlayed with the most recent census data to estimate the population distribution of exposure and socioeconomic inequalities in exposure at the census enumeration area level. The fixed effects components of the models explained 48-69 % and 63-71 % of the variance in PM2.5 and BC concentrations, respectively. Spatial variables related to road traffic and vegetation explained the most variability in the non-Harmattan models, while temporal variables were dominant in the Harmattan models. The entire GAMA population is exposed to PM2.5 levels above the World Health Organization guideline, including even the Interim Target 3 (15 μg/m3), with the highest exposures in poorer neighborhoods. The models can be used to support air pollution mitigation policies, health, and climate impact assessments. The measurement and modelling approach used in this study can be adapted to other African cities to bridge the air pollution data gap in the region.
Collapse
Affiliation(s)
- Abosede S Alli
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - Sierra N Clark
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | - Jiayuan Wang
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - James Bennett
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK
| | | | - Majid Ezzati
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK; MRC Centre for Environment and Health, School of Public Health, Imperial College London, London, UK; Regional Institute for Population Studies, University of Ghana, Accra, Ghana
| | - Michael Brauer
- School of Population and Public Health, The University of British Columbia, Vancouver, Canada
| | - James Nimo
- Department of Physics, University of Ghana, Accra, Ghana
| | | | - Solomon Baah
- Department of Physics, University of Ghana, Accra, Ghana
| | | | - Samuel Agyei-Mensah
- Department of Geography and Resource Development, University of Ghana, Accra, Ghana
| | - George Owusu
- Institute of Statistical, Social & Economic Research, University of Ghana, Accra, Ghana
| | - Jill Baumgartner
- Institute for Health and Social Policy, McGill University, Montreal, Canada; Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Canada
| | - Raphael E Arku
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA.
| |
Collapse
|
7
|
Characterisation of urban environment and activity across space and time using street images and deep learning in Accra. Sci Rep 2022; 12:20470. [PMID: 36443345 PMCID: PMC9703424 DOI: 10.1038/s41598-022-24474-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 11/15/2022] [Indexed: 11/29/2022] Open
Abstract
The urban environment influences human health, safety and wellbeing. Cities in Africa are growing faster than other regions but have limited data to guide urban planning and policies. Our aim was to use smart sensing and analytics to characterise the spatial patterns and temporal dynamics of features of the urban environment relevant for health, liveability, safety and sustainability. We collected a novel dataset of 2.1 million time-lapsed day and night images at 145 representative locations throughout the Metropolis of Accra, Ghana. We manually labelled a subset of 1,250 images for 20 contextually relevant objects and used transfer learning with data augmentation to retrain a convolutional neural network to detect them in the remaining images. We identified 23.5 million instances of these objects including 9.66 million instances of persons (41% of all objects), followed by cars (4.19 million, 18%), umbrellas (3.00 million, 13%), and informally operated minibuses known as tro tros (2.94 million, 13%). People, large vehicles and market-related objects were most common in the commercial core and densely populated informal neighbourhoods, while refuse and animals were most observed in the peripheries. The daily variability of objects was smallest in densely populated settlements and largest in the commercial centre. Our novel data and methodology shows that smart sensing and analytics can inform planning and policy decisions for making cities more liveable, equitable, sustainable and healthy.
Collapse
|
8
|
Suel E, Sorek-Hamer M, Moise I, von Pohle M, Sahasrabhojanee A, Asanjan AA, Arku RE, Alli AS, Barratt B, Clark SN, Middel A, Deardorff E, Lingenfelter V, Oza N, Yadav N, Ezzati M, Brauer M. What you see is what you breathe? Estimating air pollution spatial variation using street level imagery. REMOTE SENSING 2022; 14:3429. [PMID: 37719470 PMCID: PMC7615101 DOI: 10.3390/rs14143429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
High spatial resolution information on urban air pollution levels is unavailable in many areas globally, partially due to high input data needs of existing estimation approaches. Here we introduce a computer vision method to estimate annual means for air pollution levels from street level images. We used annual mean estimates of NO2 and PM2.5 concentrations from locally calibrated models as labels from London, New York, and Vancouver to allow for compilation of a sufficiently large dataset (~250k images for each city). Our experimental setup is designed to quantify intra and intercity transferability of image-based model estimates. Performances were high and comparable to traditional land-use regression (LUR) and dispersion models when training and testing on images from the same city (R2 values between 0.51 and 0.95 when validated on data from ground monitoring stations). Like LUR models, transferability of models between cities in different geographies is more difficult. Specifically, transferability between the three cities i.e., London, New York, and Vancouver, which have similar pollution source profiles were moderately successful (R2 values between zero and 0.67). Comparatively, performances when transferring models trained on these cities with very different source profiles i.e., Accra in Ghana and Hong Kong were lower (R2 between zero and 0.21) suggesting the need for local calibration with local calibration using additional measurement data from cities that share similar source profiles.
Collapse
Affiliation(s)
| | | | | | - Michael von Pohle
- Universities Space Research Association (USRA)
- NASA Ames Research Center
| | | | | | | | | | | | | | | | - Emily Deardorff
- Universities Space Research Association (USRA)
- NASA Ames Research Center
- San Diego State University
| | - Violet Lingenfelter
- Universities Space Research Association (USRA)
- NASA Ames Research Center
- UC Berkeley
| | | | - Nishant Yadav
- Universities Space Research Association (USRA)
- NASA Ames Research Center
| | | | | |
Collapse
|
9
|
Wang J, Alli AS, Clark S, Hughes A, Ezzati M, Beddows A, Vallarino J, Nimo J, Bedford-Moses J, Baah S, Owusu G, Agyemang E, Kelly F, Barratt B, Beevers S, Agyei-Mensah S, Baumgartner J, Brauer M, Arku RE. Nitrogen oxides (NO and NO 2) pollution in the Accra metropolis: Spatiotemporal patterns and the role of meteorology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 803:149931. [PMID: 34487903 PMCID: PMC7611659 DOI: 10.1016/j.scitotenv.2021.149931] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/17/2021] [Accepted: 08/23/2021] [Indexed: 06/02/2023]
Abstract
Economic and urban development in sub-Saharan Africa (SSA) may be shifting the dominant air pollution sources in cities from biomass to road traffic. Considered as a marker for traffic-related air pollution in cities, we conducted a city-wide measurement of NOx levels in the Accra Metropolis and examined their spatiotemporal patterns in relation to land use and meteorological factors. Between April 2019 to June 2020, we collected weekly integrated NOx (n = 428) and NO2 (n = 472) samples at 10 fixed (year-long) and 124 rotating (week-long) sites. Data from the same time of year were compared to a previous study (2006) to assess changes in NO2 concentrations. NO and NO2 concentrations were highest in commercial/business/industrial (66 and 76 μg/m3, respectively) and high-density residential areas (47 and 59 μg/m3, respectively), compared with peri-urban locations. We observed annual means of 68 and 70 μg/m3 for NO and NO2, and a clear seasonal variation, with the mean NO2 of 63 μg/m3 (non-Harmattan) increased by 25-56% to 87 μg/m3 (Harmattan) across different site types. The NO2/NOx ratio was also elevated by 19-28%. Both NO and NO2 levels were associated with indicators of road traffic emissions (e.g. distance to major roads), but not with community biomass use (e.g. wood and charcoal). We found strong correlations between both NO2 and NO2/NOx and mixing layer depth, incident solar radiation and water vapor mixing ratio. These findings represent an increase of 25-180% when compared to a small study conducted in two high-density residential neighborhoods in Accra in 2006. Road traffic may be replacing community biomass use (major source of fine particulate matter) as the prominent source of air pollution in Accra, with policy implication for growing cities in SSA.
Collapse
Affiliation(s)
- Jiayuan Wang
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - Abosede Sarah Alli
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA
| | - Sierra Clark
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London, UK; MRC Centre for Environment and Health, Imperial College London, London, UK
| | - Allison Hughes
- Department of Physics, University of Ghana, Legon, Ghana
| | - Majid Ezzati
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London, UK; MRC Centre for Environment and Health, Imperial College London, London, UK; Abdul Latif Jameel Institute for Disease and Emergency Analytics, Imperial College London, London, UK; Regional Institute for Population Studies, University of Ghana, Accra, Ghana
| | - Andrew Beddows
- NIHR HPRU in Environmental Exposures and Health, Imperial College London, UK
| | - Jose Vallarino
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - James Nimo
- Department of Physics, University of Ghana, Legon, Ghana
| | | | - Solomon Baah
- Department of Physics, University of Ghana, Legon, Ghana
| | - George Owusu
- Institute of Statistical, Social and Economic Research, University of Ghana, Legon, Ghana
| | - Ernest Agyemang
- Department of Geography and Resource Development, University of Ghana, Legon, Ghana
| | - Frank Kelly
- MRC Centre for Environment and Health, Imperial College London, London, UK; NIHR HPRU in Environmental Exposures and Health, Imperial College London, UK
| | - Benjamin Barratt
- MRC Centre for Environment and Health, Imperial College London, London, UK; NIHR HPRU in Environmental Exposures and Health, Imperial College London, UK
| | - Sean Beevers
- MRC Centre for Environment and Health, Imperial College London, London, UK
| | - Samuel Agyei-Mensah
- 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
| | - Raphael E Arku
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, USA.
| |
Collapse
|
10
|
Cai YS, Gibson H, Ramakrishnan R, Mamouei M, Rahimi K. Ambient Air Pollution and Respiratory Health in Sub-Saharan African Children: A Cross-Sectional Analysis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18189729. [PMID: 34574653 PMCID: PMC8467583 DOI: 10.3390/ijerph18189729] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/11/2021] [Accepted: 09/13/2021] [Indexed: 02/03/2023]
Abstract
Ambient air pollution is projected to become a major environmental risk in sub-Saharan Africa (SSA). Research into its health impacts is hindered by limited data. We aimed to investigate the cross-sectional relationship between particulate matter with a diameter ≤ 2.5 μm (PM2.5) and prevalence of cough or acute lower respiratory infection (ALRI) among children under five in SSA. Data were collected from 31 Demographic and Health Surveys (DHS) in 21 SSA countries between 2005–2018. Prior-month average PM2.5 preceding the survey date was assessed based on satellite measurements and a chemical transport model. Cough and ALRI in the past two weeks were derived from questionnaires. Associations were analysed using conditional logistic regression within each survey cluster, adjusting for child’s age, sex, birth size, household wealth, maternal education, maternal age and month of the interview. Survey-specific odds ratios (ORs) were pooled using random-effect meta-analysis. Included were 368,366 and 109,664 children for the analysis of cough and ALRI, respectively. On average, 20.5% children had reported a cough, 6.4% reported ALRI, and 32% of children lived in urban areas. Prior-month average PM2.5 ranged from 8.9 to 64.6 μg/m3. Pooling all surveys, no associations were observed with either outcome in the overall populations. Among countries with medium-to-high Human Development Index, positive associations were observed with both cough (pooled OR: 1.022, 95%CI: 0.982–1.064) and ALRI (pooled OR: 1.018, 95%CI: 0.975–1.064) for 1 μg/m3 higher of PM2.5. This explorative study found no associations between short-term ambient PM2.5 and respiratory health among young SSA children, necessitating future analyses using better-defined exposure and health metrics to study this important link.
Collapse
Affiliation(s)
- Yutong Samuel Cai
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Oxford OX3 9DU, UK; (H.G.); (M.M.); (K.R.)
- Deep Medicine Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
- Informal Cities Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
- Correspondence:
| | - Harry Gibson
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Oxford OX3 9DU, UK; (H.G.); (M.M.); (K.R.)
- Deep Medicine Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
- Informal Cities Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
| | - Rema Ramakrishnan
- National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford OX3 7LF, UK;
| | - Mohammad Mamouei
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Oxford OX3 9DU, UK; (H.G.); (M.M.); (K.R.)
- Deep Medicine Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
- Informal Cities Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
| | - Kazem Rahimi
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Oxford OX3 9DU, UK; (H.G.); (M.M.); (K.R.)
- Deep Medicine Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
- Informal Cities Programme, Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK
| |
Collapse
|