Design of air quality monitoring network of Luanda, Angola: Urban air pollution assessment
Introduction
Free access to clean air is one of the fundamental human rights (WHO, 2000). However, several pollutants are emitted into the atmosphere from natural or anthropogenic sources, contributing to the degradation of air quality, which puts at risk both the health of the population, vegetation and the built heritage (Cardoso, 2002). According to the WHO (2016) report, over 92% of the world's population live in regions where air pollutant concentrations are above the limits considered safe. Mabahwi et al. (2015) concluded that heart and lung pathologies are significantly more common in people who breathe polluted air than in groups living in cleaner atmospheres. Anthropogenic sources of pollution caused by industrial and urban development lead to accelerated air quality degradation and reduce the quality of life of their inhabitants (Boubel, 1994).
In developed and industrialized countries such as the United States, Canada and China, air pollution in urban areas is extensively investigated and characterized (Chen et al., 2013; Matte et al., 2013; Oiamo et al., 2012). Notwithstanding in developing countries, there is a scarcity of air quality monitors, and the eventual investigated data are not efficiently disseminated (Carvalho, 2016). Whittaker et al. (2020) conducted a research study to determine the concentrations of air pollutants (NO2, O3, SO2, PM10 and PM2.5) in St. Kitts and Nevis, in the Eastern Caribbean. They found that the concentration of pollutants was high in urban areas, being positively correlated, except for PM10. This air quality monitoring provided unprecedented information on a range of pollutants and their determinants, having contributed to an in-depth knowledge of air pollution in small developing countries.
Strategies to mitigate the harmful effects of high pollutant concentrations must be developed and implemented efficiently and cost-effectively to prevent public health risks (WHO, 2000). According to Gollata and Newig (2017), one of the most difficult challenges is to select appropriate locations for the implementation of air quality monitoring sites when designing a monitoring network. Optimising the number of sites, which configure the monitoring network, reduces costs without changing the air quality characterisation of the region. Therefore, Castro and Pires (2019) defined three fundamental criteria to be taken into account when choosing the site to optimise a network of air quality monitoring sites: (i) the representativity of the site, preferably those with high concentrations of pollutants; (ii) the number of monitored pollutants per site should be maximised; and (iii) the distance between monitoring sites. Macpherson et al. (2017) demonstrated that one way to optimise a monitoring network would be to identify redundant sites that should be excluded because they encumber the monitoring process and introduce interpretation biases on air quality. In the Republic of China, Wang et al. (2018) developed an innovative system consisting of a combination of correlation analysis, principal component analysis and cluster analysis, which ultimately helped to identify redundant monitoring sites. Three redundant sites were thus identified, resulting not only in cost savings but also in the optimisation of the city's air monitoring networks in reference.
The Institute for Security Studies of South Africa has estimated that 26 African countries will double the population growth between 2017 and 2050. Half of Africa's population will live in urban areas by 2035 (Bello-Schünemann and Aucoin, 2016). Specifically, the city of Luanda (capital of Angola) has been experiencing a population explosion in urban areas since the mid-20th century: from a population of 224 540 in 1960 to 8 234 098 in 2014 (Amaral, 1969; INE, 2016). In this context, the present work proposed a spatial distribution plan of air quality monitoring sites in Luanda according to main air pollutant emission sources in the city. Also, this study comprises: (i) the first reported monitoring campaigns of sulphur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM10, PM2.5) and carbon monoxide (CO) concentrations at two urban sites in Luanda over four weeks; (ii) the assessment of the weekend effect on the concentration of the different pollutants; and (iii) the determination of the correlation between the different pollutants in each air quality monitoring site.
Section snippets
Studied area
Luanda is limited to the west by the Atlantic Ocean, to the north by Bengo province, to the east by Cuanza Norte province and the south by Cuanza Sul province. It has a total area of 18 826 km2, 25% of which are urban areas and 75% are rural areas. The largest part of the city is located 128 m above sea level (INE, 2016). Luanda has a population of approximately 8.2 million (INE, 2016).
The warm season lasts for 9 months (from 15th August to 15th May), and the average daily maximum temperature
Air quality characterisation
At ADR site, the hourly average NO2 concentration ranged from 46.67 to 130.21 μg m−3. At CVT site, NO2 concentrations were between 35.67 and 106.96 μg m−3. According to EU human health legislation, the hourly average concentration for NO2 should not exceed 200 μg m−3 more than 18 times per year (Directive, 2008). Therefore, this limit was not exceeded at any monitoring site. Fig. 2 shows the average daily profile of NO2 concentrations at ADR and CVT sites during four weeks of study. The values
Conclusions
This work has defined the location of important air quality monitoring sites in urban areas of Luanda, an overpopulated city with characteristics of cities in developing countries. Furthermore, NO2, SO2, CO, PM2.5 and PM10 concentrations were evaluated at two monitored sites. At ADR site, average concentrations of SO2, PM2.5 and PM10 exceeded the limits set by the European Union for the protection of human health, while NO2 and CO concentrations were within the recommended limits. The average
Author contributions
Conceptualisation, A.A.B. and J.C.M.P; Methodology, P.M.C., A.A.B. and J.C.M.P.; Software, P.M.C. and J.C.M.P.; Validation, P.M.C., A.A.B. and J.C.M.P.; Formal analysis, P.M.C., A.F.E., A.A.B. and J.C.M.P.; Investigation, P.M.C. and J.C.M.P.; Resources, A.A.B.; Data curation, P.M.C., A.F.E., and J.C.M.P.; Writing – original draft Preparation, P.M.C.; Writing – review & editing, P.M.C., A.F.E., A.A.B. and J.C.M.P.; Visualization, P.M.C., A.F.E., A.A.B. and J.C.M.P.; Supervision, A.A.B. and
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was financially supported by the Base Funding - UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy – LEPABE - funded by national funds through the FCT/MCTES (PIDDAC); A.F. Esteves acknowledges the FCT Scholarship 2020.05477. BD; J.C.M. Pires acknowledges the FCT Investigator 2015 Programme (IF/01341/2015).
References (53)
- et al.
Measurements of NO2, SO2, NH3, HNO3 and O3 in west african urban environments
Atmos. Environ.
(2016) - et al.
Characterizing air pollution in two low-income neighborhoods in Accra, Ghana
Sci. Total Environ.
(2008) - et al.
Research on aerosol sources and chemical composition: past, current and emerging issues
Atmos. Res.
(2013) The air we breathe: differentials in global air quality monitoring
The Lancet Resp. Med.
(2016)- et al.
Decision support tool to improve the spatial distribution of air quality monitoring sites
Atmos. Pollut. Res.
(2019) - et al.
Measurements of particulate matter concentrations at a landfill site (Crete, Greece)
Waste Manag.
(2010) - et al.
Ground-high altitude joint detection of ozone and nitrogen oxides in urban areas of Beijing
J. Environ. Sci.
(2013) - et al.
Identification and assessment of ship emissions and their effects in the harbour of Göteborg, Sweden
Atmos. Environ.
(2001) - et al.
Analysis of unregulated emissions from an off-road diesel engine during realistic work operations
Atmos. Environ.
(2011) - et al.
Aromatic compound emissions from municipal solid waste landfill: emission factors and their impact on air pollution
Atmos. Environ.
(2016)
Urban air quality and human health effects in Selangor, Malaysia
Proc.-Social Behav. Sci.
A mixed integer programming model for National Ambient Air Quality Standards (NAAQS) attainment strategy analysis
Environ. Model. Software
Challenges and perspectives of greenhouse gases emissions from municipal solid waste management in Angola
Energy Rep.
Impact of harbour activities on local air quality: a review
Environ. Pollut.
Impact of maritime transport emissions on coastal air quality in Europe
Atmos. Environ.
Identifying redundant monitoring stations in an air quality monitoring network
Atmos. Environ.
The Unheralded Polluter: Cement Industry Comes Clean on its Impact
Nota sobre a evolução da população de Luanda e dos seus muceques
A pilot study of gaseous pollutants' measurement (NO2, SO2, NH3, HNO3 and O3) in Abidjan, Côte d'Ivoire: contribution to an overview of gaseous pollution in African cities
Atmos. Chem. Phys.
Fundamentals of Air Pollution
Qualidade de ar na área metropolitana do Porto, 1994-1999
Average hourly concentrations of air contaminants in selected urban, town, and rural sites
Arch. Environ. Contam. Toxicol.
Área Industrial - Cimangola
Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe
Off. J. Euro. Union, L
Policy implementation through multi-level governance: analysing practical implementation of EU air quality directives in Germany
J. Eur. Publ. Pol.
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Peer review under responsibility of Turkish National Committee for Air Pollution Research and Control.