A simplified anthropogenic aerosol model for use in climate studies is developed and implemented within the regional climate model RegCM. The model includes sulphur dioxide, sulphate, hydrophobic and ...hydrophilic black carbon (BC) and organic carbon (OC) and is run for the winter and summer seasons of 2000 over a large domain extending from northern Europe to south tropical Africa. An evaluation of the model performance is carried out in terms of surface concentrations and aerosol optical depths (AODs). For sulphur dioxide and sulphate concentration, comparison of simulated fields and experimental data collected over the EMEP European network shows that the model generally reproduces the observed spatial patterns of near-surface sulphate. Sulphate concentrations are within a factor of 2 of observations in 34% (JJA) to 57% (DJF) of cases. For OC and BC, simulated concentrations are compared to different datasets. The simulated and observed values agree within a factor of 2 in 56% (DJF) to 62% (JJA) of cases for BC and 33% (JJA) to 64% (DJF) for OC. Simulated AODs are compared with ground-based (AERONET) and satellite (MODIS, MISR, TOMS) AOD datasets. Simulated AODs are in the range of AERONET and MISR data over northern Europe, and AOD spatial patterns show consistency with MODIS and TOMS retrievals both over Europe and Africa. The main model deficiencies we find are: (i) an underestimation of surface concentrations of sulphate and OC during the summer and especially over the Mediterranean region and (ii) a general underestimation of AOD, most pronounced over the Mediterranean basin. The primary factors we identify as contributing to these biases are the lack of natural aerosols (in particular, desert dust, secondary biogenic aerosols and nitrates), uncertainties in the emission inventories and aerosol cycling by moist convection. Also, in view of the availability of better observing datasets (e.g. as part of the AMMA project), we are currently working on improving these aspects of the model before applying it to climate studies. Despite the deficiencies identified above, we assess that our model shows a performance in line with that other coupled climate/aerosol models and can presently provide a useful tool for sensitivity and process studies.
Urbanization is an issue that is strongly emerging in southern West Africa (sWA). There is a lack of full understanding on chemical compositions and personal exposure levels to fine particulate ...matter (hereafter defined as PE PM2.5) and its health risks related to various anthropogenic sources in this region. In this study, PE PM2.5 was studied in dry (January) and wet (July) seasons of 2016 for the first time to characterize the contributions of a domestic fire site (DF) to the exposure of women and a waste burning site (WB) to that of students in Abidjan, Côte d'Ivoire, and a motorcycle traffic site (MT) to that of drivers in Cotonou, Benin. The average PE PM2.5 mass concentrations were 331.7±190.7, 356.9±71.9 and 242.8±67.6 µg m−3 at DF, WB and MT sites for women, students and drivers, which were 2.4, 10.3 and 6.4 times the ambient PM2.5 concentrations, respectively. Elevated PE PM2.5 levels in the dry season were found at DF (358.8±100.5 µg m−3), WB (494.3±15.8 µg m−3) and MT (335.1±72.1 µg m−3) sites, on average 15 % higher than that at DF and 55 % higher at both WB and MT sites in the wet season. The seasonal variations were attributed to emission sources, meteorological factors and personal activities. In addition, the results show that geological material (35.8 %, 46.0 % and 42.4 %) and organic matter (34.1 %, 23.3 % and 24.9 %) were the major components of PE PM2.5 at DF, WB and MT sites. It is worth noting that the contribution of heavy metals was higher at WB (1.0 %) than at DF (0.7 %) and MT (0.4 %) sites, strongly influenced by waste burning emission. This results in the highest non-cancer risks of heavy metals to students, 5.1 and 4.8 times the values for women and drivers, respectively. By conducting organic speciation, fingerprints were used to access the exposure and identify the source contributions from typical local anthropogenic sources. The women's exposure concentration to particulate polycyclic aromatic hydrocarbons (PAHs) at DF (77.4±47.9 ng m−3) was 1.6 and 2.1 times, respectively, that of students at WB (49.9±30.7 ng m−3) and of drivers at MT (37.0±7.4 ng m−3). This can be associated with the higher contributions from solid fuels' burning and meat grilling activities to women, resulting in a level 5 times in exceedance of the cancer risk safety threshold (1×10-6). Phthalate esters (PAEs), commonly used as plasticizers in products, were in high levels in the student exposure PM2.5 samples (1380.4±335.2 ng m−3), owing to obvious waste burning activities nearby. The drivers' exposures to fossil fuel combustion markers of hopanes in PE PM2.5 at MT (50.9±7.9 ng m−3) was 3.0–3.3 times those for women at DF (17.1±6.4 ng m−3) and students at WB (15.6±6.1 ng m−3). Overall, the current study shows that wood combustion, waste burning, fugitive dust and motor vehicle emissions were the dominant sources of PE PM2.5 and mainly contributed to its toxicities. The exposure to the heavy metals Pb and Mn caused high non-cancer risks to students at WB, while the severe cancer risk of PAHs was found for women at DF via inhalation. The result of this study provides original data, initial perspective of PM2.5 personal exposure and health risk assessment in the developing areas. The information encourages the governments to improve the air quality and living standards of residents in this region.
Naturally and anthropogenically emitted aerosols, which are determined by their physical and chemical properties, have an impact on both air quality and the radiative properties of the earth. An ...important source of atmospheric particulate matter (PM) in South Africa is household combustion for space heating and cooking, which predominantly occurs in low-income urban settlements. The aim of this study was to conduct a detailed size-resolved assessment of chemical characteristics of aerosols associated with household combustion through the collection of particulates in low-income urban settlements in South Africa to quantify the extent of the impacts of atmospheric pollution. Outdoor (ambient) and indoor aerosols in different size fractions were collected during summer and winter in four low-income urban settlements located in the north-eastern interior on the South African Highveld, i.e. Kwadela, Kwazamokuhle, Zamdela, and Jouberton. Mass concentration and chemical composition was determined for three size fractions, namely, PM.sub.1, PM.sub.2.5, and PM.sub.2.5-10 . The highest concentrations of particulates were measured indoors with the highest mass concentration determined in the indoor PM.sub.2.5-10 (coarse) size fraction. However, the highest mass concentrations were determined in PM.sub.1 in all outdoor aerosol samples collected during winter and summer, and in indoor samples collected during summer.
Several field campaigns were conducted in the framework of the
Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA)
project to measure a broad range of atmospheric constituents. ...Here we
present the analysis of an unprecedented and comprehensive dataset
integrating up to 56 volatile organic compounds (VOCs) from ambient
sites and emission sources. VOCs were collected on multi-sorbent tubes in the
coastal city of Abidjan, Côte d'Ivoire, in winter and summer 2016 and
later analysed by gas chromatography coupled with flame ionization and mass
spectrometer detectors (GC-FID and GC-MS) at the laboratory. The comparison between VOC emission source profiles and ambient profiles
suggests the substantial impact of two-stroke motorized two-wheel vehicles
and domestic fires on the composition of Abidjan's atmosphere. However,
despite high VOC concentrations near-source, moderate ambient levels were
observed (by factors of 10 to 4000 lower), similar to the concentrations
observed in northern mid-latitude urban areas. Besides photochemistry, the
reported high wind speeds seem to be an essential factor that regulates air
pollution levels in Abidjan. Emission ratios (ΔVOC∕ΔCO) were established based on
real-world measurements achieved for a selected number of representative
combustion sources. Maximum measured molar mass emissions were observed from
two-wheel vehicles, surpassing other regional sources by 2 orders of
magnitude. Local practices like waste burning also make a significant
contribution to VOC emissions, higher than those from light-duty vehicles by
1.5 to 8 orders of magnitude. These sources also largely govern the VOC's
atmospheric impacts in terms of OH reactivity, secondary organic aerosol
formation (SOAP), and photochemical ozone creation potential (POCP). While
the contribution of aromatics dominates the atmospheric impact, our
measurements reveal the systematic presence of anthropogenic terpenoids in
all residential combustion sectors. Finally, emission factors were used to
retrieve and quantify VOC emissions from the main anthropogenic source
sectors at the national level. Our detailed estimation of VOC emissions
suggests that the road transport sector is the dominant source in Côte
d'Ivoire, emitting around 1200 Gg yr−1 of gas-phase VOCs. These new
estimates are 100 and 160 times larger than global inventory estimations
from MACCity or EDGAR (v4.3.2), respectively. Additionally, the residential
sector is largely underestimated in the global emission inventories, by
factors of 13 to 43. Considering only Côte d'Ivoire, these new estimates
for VOCs are 3 to 6 times higher than the whole of Europe. Given the
significant underestimation of VOC emissions from the transport and residential
sectors in Côte d'Ivoire, there is an urgent need to build more
realistic and region-specific emission inventories for the entire West
African region. This might be true not only for VOCs, but also for all atmospheric
pollutants. The lack of waste burning, wood fuel burning and charcoal
burning, and fabrication representation in regional inventories also needs to
be addressed, particularly in low-income areas where these types of
activities are ubiquitous sources of VOC emissions.
Southern West Africa (SWA) is influenced by large numbers of aerosol particles of both anthropogenic and natural origins. Anthropogenic aerosol emissions are expected to increase in the future due to ...the economical growth of African megacities. In this paper, we investigate the aerosol optical depth (AOD) in the coastal area of the Gulf of Guinea using sun photometer and MODIS satellite observations. A network of lightweight handheld sun photometers have been deployed in SWA from December 2014 to April 2017 at five different locations in Côte d'Ivoire and Benin. The handheld sun photometer measures the solar irradiance at 465, 540 and 619 nm and is operated manually once per day. Handheld-sun-photometer observations are complemented by available AERONET sun photometer observations and MODIS level 3 time series between 2003 and 2019. MODIS daily level 3 AOD agrees well with sun photometer observations in Abidjan and Cotonou (correlation coefficient R=0.89 and RMSE = 0.19). A classification based on the sun photometer AOD and Ãngström exponent (AE) is used to separate the influence of coarse mineral dust and urban-like aerosols. The AOD seasonal pattern is similar for all the sites and is clearly influenced by the mineral dust advection from December to May. Sun photometer AODs are analyzed in coincidence with surface PM.sub.2.5 concentrations to infer trends in the particulate pollution levels over conurbations of Abidjan (Côte d'Ivoire) and Cotonou (Benin). PM.sub.2.5 -to-AOD conversion factors are evaluated as a function of the season and the aerosol type identified in the AE classification. The highest PM.sub.2.5 concentrations (up to 300 µg m.sup.-3) are associated with the advection of mineral dust in the heart of the dry season (December-February). Annual means are around 30 µg m.sup.-3, and 80 % of days in the winter dry season have a value above 35 µg m.sup.-3, while concentrations remain below 16 µg m.sup.-3 from May to September. No obvious trend is observed in the 2003-2019 MODIS-derived PM.sub.2.5 time series. However the short dry period (August-September), when urban-like aerosols dominate, is associated with a monotonic trend between 0.04 and 0.43 µgm-3yr-1 in the PM.sub.2.5 concentrations over the period 2003-2017. The monotonic trend remains uncertain but is coherent with the expected increase in combustion aerosol emissions in SWA.
Air quality degradation is a major issue in the large conurbations on
the shore of the Gulf of Guinea. We present for the first time
PM2.5 time series collected in Cotonou, Benin, and Abidjan,
Côte ...d'Ivoire, from February 2015 to March 2017. Measurements were
performed in the vicinity of major combustion aerosol sources:
Cotonou/traffic (CT), Abidjan/traffic (AT), Abidjan/landfill (AL) and
Abidjan/domestic fires (ADF). We report the weekly PM2.5 mass and
carbonaceous content as elemental (EC) and organic (OC) carbon
concentrations. We also measure the aerosol optical depth (AOD) and the
Ångström exponent in both cities. The average PM2.5 mass
concentrations were 32 ± 32, 32 ± 24 and
28 ± 19 µg m−3 at traffic sites CT and AT and landfill
site AL, respectively. The domestic fire site shows a concentration of
145 ± 69 µg m−3 due to the contribution of smoking and
roasting activities. The highest OC and EC concentrations were also measured
at ADF at 71 ± 29 and 15 ± 9 µg m−3,
respectively, while the other sites present OC concentration between 8 and
12 µg m−3 and EC concentrations between 2 and
7 µg m−3. The OC ∕ EC ratio is 4.3 at CT and 2.0 at AT.
This difference highlights the influence of two-wheel vehicles using gasoline
in Cotonou compared to that of four-wheel vehicles using diesel fuel in
Abidjan. AOD was rather similar in both cities, with a mean value of 0.58 in
Cotonou and of 0.68 in Abidjan. The seasonal cycle is dominated by the large
increase in surface mass concentration and AOD during the long dry season
(December–February) as expected due to mineral dust advection and biomass
burning activities. The lowest concentrations are observed during the short
dry season (August–September) due to an increase in surface wind speed
leading to a better ventilation. On the other hand, the high
PM2.5 ∕ AOD ratio in the short wet season (October–November)
indicates the stagnation of local pollution.
Anthropogenic emissions are the result of many different economic sectors, including transportation, power generation, industrial, residential and commercial activities, waste treatment and ...agricultural practices. Air quality models are used to forecast the atmospheric composition, analyze observations and reconstruct the chemical composition of the atmosphere during the previous decades. In order to drive these models, gridded emissions of all compounds need to be provided. This paper describes a new global inventory of emissions called CAMS-GLOB-ANT, developed as part of the Copernicus Atmosphere Monitoring Service (CAMS; https://doi.org/10.24380/eets-qd81, Soulie et al., 2023). The inventory provides monthly averages of the global emissions of 36 compounds, including the main air pollutants and greenhouse gases, at a spatial resolution of 0.1° × 0.1° in latitude and longitude, for 17 emission sectors. The methodology to generate the emissions for the 2000–2023 period is explained, and the datasets are analyzed and compared with publicly available global and regional inventories for selected world regions. Depending on the species and regions, good agreements as well as significant differences are highlighted, which can be further explained through an analysis of different sectors as shown in the figures in the Supplement.
Particulate Matter (PM) Low-Cost Sensors (LCS) can be used to monitor air quality in regions with limited access to reference monitors. This study carried out within the framework of the Improving ...Air Quality in West Africa (IAQWA) project provides high temporal resolution of data on fine aerosol (PM
2.5
) mass concentrations in Abidjan (Cote d'Ivoire) and Accra (Ghana) through the deployment of field calibrated Real-time Affordable Multi-pollutant (RAMP) monitors. From February 2020 to June 2021, RAMPs were deployed at five sites in Abidjan and four sites in Accra. Using a temporal resolution of 15 seconds, the datasets provided by RAMPs allowed a comparative analysis of diurnal, daily and seasonal variability of PM
2.5
concentrations for different urban sites with distinct pollution sources, over an extended period of time. Diurnal variations in PM
2.5
concentrations showed prominent morning peaks related to traffic rush hours reaching up to 50 μg m
−3
. Evening peaks were significant for sites in residential neighborhoods, and pointed to residential type pollution sources. Seasonal differences are analysed over a yearly cycle and maximum values are found during the so-called long dry season (Harmattan), between December and February. During a prominent pollution episode in January 2021 observed by the ground network, analysis of 3D satellite data, revealed Saharan dust transport as an additional source of (fine) aerosol pollution significantly increasing PM
2.5
. The same episode also revealed a limitation of LCS - an inability to adequately capture dust-dominated pollution, which can be quantified by reference monitors. Annual average PM
2.5
concentrations vary between 17 and 26 μg m
−3
. PM
2.5
differences between sites within a city, especially between traffic impacted and urban background sites, are larger than the differences between the two cities. These annual averages exceed World Health Organization (WHO) annual pollution thresholds from the 2005 (10 μg m
−3
) and 2021 (5 μg m
−3
) guidelines.
Study uses real-time monitors to analyze PM
2.5
in Abidjan & Accra, revealing diurnal & seasonal patterns, highlighting city differences, & showing Saharan dust impact. Emphasizes RAMPs' efficacy & need for robust monitoring in West African cities.
Particulate Matter (PM) Low-Cost Sensors (LCS) can be used to monitor air quality in regions with limited access to reference monitors. This study carried out within the framework of the Improving ...Air Quality in West Africa (IAQWA) project provides high temporal resolution of data on fine aerosol (PM 2.5 ) mass concentrations in Abidjan (Cote d'Ivoire) and Accra (Ghana) through the deployment of field calibrated Real-time Affordable Multi-pollutant (RAMP) monitors. From February 2020 to June 2021, RAMPs were deployed at five sites in Abidjan and four sites in Accra. Using a temporal resolution of 15 seconds, the datasets provided by RAMPs allowed a comparative analysis of diurnal, daily and seasonal variability of PM 2.5 concentrations for different urban sites with distinct pollution sources, over an extended period of time. Diurnal variations in PM 2.5 concentrations showed prominent morning peaks related to traffic rush hours reaching up to 50 μg m −3 . Evening peaks were significant for sites in residential neighborhoods, and pointed to residential type pollution sources. Seasonal differences are analysed over a yearly cycle and maximum values are found during the so-called long dry season (Harmattan), between December and February. During a prominent pollution episode in January 2021 observed by the ground network, analysis of 3D satellite data, revealed Saharan dust transport as an additional source of (fine) aerosol pollution significantly increasing PM 2.5 . The same episode also revealed a limitation of LCS – an inability to adequately capture dust-dominated pollution, which can be quantified by reference monitors. Annual average PM 2.5 concentrations vary between 17 and 26 μg m −3 . PM 2.5 differences between sites within a city, especially between traffic impacted and urban background sites, are larger than the differences between the two cities. These annual averages exceed World Health Organization (WHO) annual pollution thresholds from the 2005 (10 μg m −3 ) and 2021 (5 μg m −3 ) guidelines.
Anthropogenic emissions are the result of many different activities, related to transportation, power generation, industrial, residential and commercial activities, waste treatment and agriculture ...practices. Air quality models are used to forecast the atmospheric composition, analyse observations and reconstruct the chemical composition of the atmosphere during the previous decades. In order to drive these models, gridded emissions of all compounds emitted at the surface need to be provided. This paper describes a new global inventory of emissions called CAMS-GLOB-ANT, developed as part of the Copernicus Atmosphere Monitoring Service (CAMS). The inventory provides monthly averages of the global emissions of 36 compounds, including the main air pollutants and greenhouse gases, at a spatial resolution of 0.1x0.1 degree in latitude and longitude, for 17 emission sectors. The methodology to generate the emissions for the 2000–2023 period is explained, and the datasets are analysed and compared with publicly available global and regional inventories for selected world regions.
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