ABSTRACT
Background: Air pollution has caused health and environmental problems around the world. In this study we analysed the temporal evolution of air pollution in Cotonou regarding the standards of Benin and of World Health Organization (WHO).
Methods: Solar-powered electrochemical sensors (CO: carbon monoxide, SO2: sulphur dioxide, and O3/NO2: ozone/nitrogen dioxide) and photoionization detectors (for NMVOC: nonmethane volatile organic compounds) were permanently installed and monitored from June 2019 to March 2020 at Akpakpa PK3 (A) and Vèdokô Cica-Toyota (B) roundabouts.
Results: CO and SO2 concentrations at both roundabouts were significantly higher on weekends than on weekdays. The concentrations of NMVOC and O3 / NO2 on Sunday differed considerably from the other days of the week at A and B, respectively. There was a positive linear correlation between the concentrations of CO and SO2, O3 / NO2 and SO2, and CO O3 / NO2 to B, and only between CO and O3 / NO2, in A.
At the two sites, the average of SO2 concentrations (in μg/m3) were higher than the WHO standard (500) for an exposure of 10 minutes (2258 A and 2143 B) and the Benin standard (1300) for 1 hour exposure (2181 in A and 2092 in B).
Conclusion: Air pollution varies in hours and days in Cotonou. Standards are respected, except for SO2. Particular attention should be paid to the concentrations and the possible sources of gas. More sophisticated monitoring system should be put in place.
REFERENCES
World Health Organization. Pollution de l’air. Accessed: 2021 Apr 10. Available from: http://www.who.int/topics/air_pollution/fr/
World Health Organization. 9 out of 10 people worldwide breathe polluted air, but more countries are taking action. Accessed: 2020 Jul 8. Available from: https://www.who.int/news/item/02-05-2018-9-out-of-10-people-worldwide-breathe-polluted-air-but-more-countries-are-taking-action
World Health Organization.7 million premature deaths annually linked to air pollution. Accessed: 2021 Apr 10. Available from: https://www.who.int/news/item/25-03-2014-7-million-premature-deaths-annually-linked-to-air-pollution
Le Monde.fr [Internet]. [En Afrique de l’Ouest, une pollution mortelle mais d’ampleur inconnue].[in French]. 2019 Nov 29. Accessed: 2020 Jul 8. Available from: https://www.lemonde.fr/afrique/article/2019/11/29/en-afrique-de-l-ouest-une-pollution-mortelle-mais-d-ampleur-inconnue_6021103_3212.html
Loury R. [Afrique: la pollution atmosphérique en plein boom – Journal de l’environnement].[in French]. 2016. Accessed: 2020 Jul 8]. Available from: http://www.journaldelenvironnement.net/article/afrique-la-pollution-atmospherique-en-plein-boom,75885
Baumbach G, Vogt U, Hein KRG, et al. Air pollution in a large tropical city with a high traffic density — results of measurements in Lagos, Nigeria. Sci Total Environ 1995;169:25–31. DOI: https://doi.org/10.1016/0048-9697(95)04629-F
Ndong Ba A, Verdin A, Cazier F, et al. Individual exposure level following indoor and outdoor air pollution exposure in Dakar (Senegal). Environ Pollut Barking Essex 1987 2019;248:397-407. DOI: https://doi.org/10.1016/j.envpol.2019.02.042
Dionisio KL, Arku RE, Hughes AF, et al. Air pollution in Accra neighborhoods: Spatial, socioeconomic, and temporal patterns. Environ Sci Technol 2010;44:2270–6. DOI: https://doi.org/10.1021/es903276s
Doumbia EHT. [Caractérisation physico-chimique de la pollution atmosphérique en Afrique de l’Ouest et étude d’impact sur la santé].[PhD Thesis in French]. Université de Toulouse, Université Toulouse III – Paul Sabatier. 2012. Accessed: 2021 Jan 22. Available from: http://thesesups.ups-tlse.fr/1915/
Ozer P, Laghdaf MBOM, Lemine SOM, Gassani J. Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal visibility data. Water Air Soil Pollut 2007;178:79–87. DOI: https://doi.org/10.1007/s11270-006-9152-8
Obeng-Odoom F. The State of African Cities 2010: Governance, inequality and urban land markets. Cities 2013;31:425–9. DOI: https://doi.org/10.1016/j.cities.2012.07.007
Kouao AKR, N’datchoh ET, Yoboue V, et al. Exposure to indoor and outdoor air pollution among children under five years old in urban area. Glob J Environ Sci Manag 2019;5:191–202.
Le Point [Internet]. [Pollution de l’air: l’Afrique sur le point d’étouffer ?].[in French]. 2018. Accessed: 2021 Apr 10. Available from: https://www.lepoint.fr/afrique/pollution-de-l-air-l-afrique-sur-le-point-d-etouffer-18-05-2018-2219507_3826.php
Heft-Neal S, Burney J, Bendavid E, Burke M. Robust relationship between air quality and infant mortality in Africa. Nature 2018;559:254–8. DOI: https://doi.org/10.1038/s41586-018-0263-3
Lawin H, Fanou LA, Kpangon AA, et al. Comparison of motorcycle taxi driver’s respiratory health using an air quality standard for carbon monoxide in ambient air: a pilot survey in Benin. Pan Afr Med J 2018;30:113. DOI: https://doi.org/10.11604/pamj.2018.30.113.14975
Avogbe PH, Ayi-Fanou L, Cachon B, , et al. Hematological changes among Beninese motor-bike taxi drivers exposed to benzene by urban air pollution. Afr J Environ Sci Technol 2011;5:464–72.
Ayi-Fanou L, Avogbe PH, Fayomi B, et al. DNA-adducts in subjects exposed to urban air pollution by benzene and polycyclic aromatic hydrocarbons (PAHs) in Cotonou, Benin. Environ Toxicol 2011;26:93–102. DOI: https://doi.org/10.1002/tox.20533
Ashfaq A, Sharma P. Environmental effects of air pollution and application of engineered methods to combat the problem. J Industr Pollut Control 2012:45739.
Ukpebor EE, Ukpebor JE, Eromomene F, et al. Spatial and diurnal variations of carbon monoxide (CO) pollution from motor vehicles in an urban centre. Pol J Environ Stud 2010;19:817-23.
Rozante JR, Rozante V, Souza Alvim D, et al. Variations of carbon monoxide concentrations in the megacity of São Paulo from 2000 to 2015 in different time scales. Atmosphere 2017;8:81. DOI: https://doi.org/10.3390/atmos8050081
Government of Canada [Internet]. Common air pollutants: ground-level ozone. 2004. Accessed: 2020 Jul 3. Available from: https://www.canada.ca/en/environment-climate-change/services/air-pollution/pollutants/common-contaminants/ground-level-ozone.html
Menchaca-Torre HL, Mercado-Hernández R, Mendoza-Domínguez A. Diurnal and seasonal variation of volatile organic compounds in the atmosphere of Monterrey, Mexico. Atmospheric Pollut Res 2015;6:1073–81. DOI: https://doi.org/10.1016/j.apr.2015.06.004
Mégie G. Ozone and the oxidizing properties of the troposphere. Meteorologie 1996;13:11-28. DOI: https://doi.org/10.4267/2042/51171
Gour AA, Singh SK, Tyagi SK, Mandal A. Weekday/weekend differences in air quality parameters in Delhi, India. Int J Res Engin Technol 2013;1:69-76.
US Environmental Protection Agency [Internet]. Technical overview of volatile organic compounds. 2014. Accessed: 2020 Jul 11. Available from: https://www.epa.gov/indoor-air-quality-iaq/technical-overview-volatile-organic-compounds
US Environmental Protection Agency [Internet]. Volatile organic compounds’ impact on indoor air quality. US EPA. 2014 Accessed: 2020 Jul 11. Available from:https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality
La Nouvelle Tribune [Internet]. [Réglementation de la circulation des camions à Cotonou: L’arrêté de Toboula qui sème la confusion].[in French]. 2018. Accessed: 2020 Jul 11. Available from: https://lanouvelletribune.info/2018/03/reglementation-circulation-camions-a-cotonou-larrete-de-toboula-qui-seme-la-confusion/
US Environmental Protection Agency [Internet]. Sulfur dioxide basics. 2016. Accessed: 2020 Aug 11. Available from: https://www.epa.gov/so2-pollution/sulfur-dioxide-basics
Memoire Online [Internet]. [Problématique de l’interdiction de la vente de carburant dans le secteur informel à Cotonou au Bénin].[in French]. 2009. Accessed: 2020 Jul 3. Available from: https://www.memoireonline.com/09/13/7345/Problematique-de-l-interdiction-de-la-vente-de-carburant-dans-le-secteur-informel–Cotonou-au-Be.html
Le Point [Internet]. Afrique: le scandaleux commerce des carburants toxiques. 2016. Accessed: 2020 Jun 26. Available from: https://www.lepoint.fr/afrique/afrique-le-scandaleux-commerce-des-carburants-toxiques-29-09-2016-2072219_3826.php
Public Eye [Internet]. Les négociants suisses inondent l’Afrique de carburants toxiques. 2016. Accessed: 2020 Jul 10. Available from: https://www.publiceye.ch/fr/coin-medias/communiques-de-presse/detail/les-negociants-suisses-inondent-lafrique-de-carburants-toxiques/
Public Eye [Internet]. Dirty diesel. 2016. Accessed: 2020 Jul 10. Available from: https://www.publiceye.ch/fileadmin/doc/Rohstoffe/2016_PublicEye_Dirty_Diesel_FR_Magazin_1.pdf
Cancer Environnement [Internet]. Composés organiques volatils et risque de cancer. 2018. Accessed: 2020 Jul 11. Available from: https://www.cancer-environnement.fr/343-Composes-Organiques-Volatils-COV-dans-lair.ce.aspx
Lee P, Saylor R, McQueen J. Air quality monitoring and forecasting. Basel: MDPI; 2018. DOI: https://doi.org/10.3390/atmos9030089
US Environmental Protection Agency [Internet]. Air topics. 2016. Accessed: 2021 Apr 10. Available from: https://www.epa.gov/environmental-topics/air-topics
World Health Organization. Lignes directrices OMS relatives à la qualité de l’air: particules, ozone, dioxyde d’azote et dioxyde de soufre. 2006. Accessed: 2021 Apr 10. Available from: https://www.who.int/fr/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health
Republic of Benin. [Décret nº 2001-110 fixant les normes de qualité de l'air en République de Bénin].[in French]. 2011. Accessed: 2021 Apr 10. Available from: https://www.informea.org/fr/node/104622