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Quantifying the Visibility and Human Health Effects of Aerosol Optical Depth Chemical Species in Some Cities of West Africa
Abstract
The high level of chemical compounds in the atmosphere of many West African cities is worrying because of the potential threats to human health and other environmental problems they are known for. However, routine monitoring and adequate control measures are rare due to technical, social and economic problems. This paper analyzed the health and visibility effects of aerosol optical depth chemical species within some West African cities from (2010–2020) using the aerosol optical depth data set obtained from the European Center for Medium-Range Weather Forecasts (ECMWF-UK). The results of the analysis showed that the visual range of the study cities ranged from 4600 to 5600 km, while the potentials of human health effects TPHhe existing in the cities are between 0.9 and 1.2 signifying low visibility and high potential threats to human health. There exist several weak and also inverse correlations between the variability of the aerosol optical depth chemical species in the study cities with a coefficient of determination ranging from 0.01 to 0.98. This implies that aerosol loads are not uniformly distributed across cities and also come from a plethora of sources across cities. The variability of aerosol optical depth chemical species in the West African cities presented is useful in evaluating and improving the accuracy of the models for aerosol prediction in the region and can assist in the easy determination of aerosol effects in the atmosphere. The total chemical composition of aerosol loads was gauged with acceptable standards limit set by Environmental Protection Agencies to determine the health effects on humans and the results are useful not only in measuring the health implication but also in evaluating safety measures to tackle the effects, while the identified poor visibility in the cities is a clear call for policymakers to step up regulation and design action to tackle the menace of visibility reduction in these cities.
... Studies conducted by Anuforon et al. (2007); Reeves et al. (2010); Zhang et al. (2014);Zhao et al. (2017); Ayua et al. (2024) on the aerosol distribution in West Africa all pointed out that aerosol concentrations have a comprehensible seasonal variation with the highest concentrations occurring in December-January each year. However, these studies could not establish the correlations between the AOD loadings across the cities. ...
... The study area experiences regular pollution events, particularly during spring and winter, as a result of its unique geography and the significant amount of anthropogenic primary aerosol emissions and secondary aerosol production as reported by Ayua et al. (2024). AOD shows a rapid decrease in its entire species with an increase in altitude, with about 460% contribution to AOD coming from regions below 200 km (Wang et al. 2022). ...
... Hence, there is statistical significance of the differences among them in the AOD in each city in West Africa. This concept further corroborates the evidence of different anthropogenic activities that are peculiar to each city as reported by Yang et al. (2013); Ayua et al. (2024). The Intraclass Correlation Coefficient (ICC) from the one-way ANOVA is 0.042064. ...
A prominent factor used in evaluating aerosol content and air quality is the Aerosol Optical Depth. Cities in Africa remain vulnerable to environmental issues such as air pollution since there are few appropriate control mechanisms and infrequent routine monitoring due to social, technological, and financial issues. This paper analyzes the Aerosol Optical Depth (AOD) dataset of fifty-five locations in West Africa (2010–2020) using geographic information system software (QGIS). It is observed that the AOD values have a varying spatial pattern signifying that the source of high AOD diffused due to rainfall and wind dynamics. The spatial analysis shows that AOD over West Africa is consistently increasing over the years (2019–2020) showing four locations (south-south Nigeria, coastal Mauritania, northern Mali, and coastal Sierra Leone) with reasonably high AOD values. The AOD dispersion in these four locations is consistent with AOD values of > 0.4. These four cities with little fluctuations in their aerosol load are most likely having their sources of AOD from nature, which hardly changes on timescales of a year or season. The seasonal analysis shows higher mean values of AOD (0.30 ≤ AOD ≤ 0.80) occurring during the winter across all the cities studied with the highest numbers reported in Kanema City of Sierra Leone and the least mean values (0.20 ≤ AOD ≤ 0.40) during the summer occurring in Ngaoundere city of Cameroon and all the Liberian cities. Strong and positive correlations are observed between Portonovo/Kumasi, Lome/Kumasi, Bondouke/Bouake, and Praia/Santiago with R² values ranging from 0.8 to 1.0. Weaker correlations are reported at Kandi/Fderik, Bonfara/Fderik, Soma/Accra, and Banjul/Accra, all with R² values ranging from 0.0001 to 0.002. Determining the fundamental common causes of air pollution in West Africa can be greatly aided by the AOD correlations provided. This may help reduce the time required to address episodes of air pollution at the regional level because communities may utilize the data to create more targeted air pollution programs and provide citizens with better guidance on what to do in the event of major air pollution incidents or disasters.
Satellite-derived aerosol data from Modern-Era Retrospective Analysis for Research and Application, version 2 (MERRA2), have received a lot of attention and offer substantial information for estimating aerosols, as well as for air quality,
climate, and health assessments.This study proposes an integration of multiple measurement approaches, including empirical modeling of MERRA-2 aerosol components, namely black carbon (BC), organic carbon (OC), dust, sea-salt, and sulfate (SO4
2−), ground-based PM2.5, and the feasibility of machine learning to simulate PM2.5 concentrations and develop
accurate and robust models in two distinct climatic regions in India—Rajasthan (arid/semi-arid) and Kerala (humid/semihumid). The 42-year MERRA-2 aerosol datasets (1980–2022) were obtained at the daily and monthly resolution, while
hourly ground-based PM2.5 datasets were collected from fourteen (14) continuous ambient air quality monitoring stations
(CAAQMS) in Rajasthan and Kerala. Firstly, we examined long-term trends of empirical-based PM2.5 [MERRA2-EEPM2.5] from 1980 to 2022, and results indicated a significant rise in PM2.5 levels in both Rajasthan and Kerala post-2000,
largely attributed to commercialization and industrialization. A detailed correlation analysis of MERRA-2 aerosol components with PM2.5 highlighted that dust, BC, OC, and SO4
2- were the main contributors in the arid and semi-arid regions of
Rajasthan. In contrast, Kerala’s humid regions showed differences among these components, highlighting the complexity
of regional aerosol impacts. Further, MERRA2-EE-PM2.5 underestimates, implying the need for accurate weighting of
each aerosol component and advanced models with meteorological parameters. Therefore, we ensembled three machine
learning (ML) models: random forest (RF), gradient boosting (GB), and k-nearest neighbour (k-NN) to estimate modelledPM2.5 using MERRA-2 aerosol components and meteorological parameters. The results showed an R2
value increase from
0.42 to 0.62 after accounting for meteorological parameters in the ML models. These findings highlight the ineptness of
conventional MERRA2-EE-PM2.5 and emphasize the need for customized regional models that assign appropriate weights
to each aerosol component according to specific climate conditions. Our findings support the potential of machine learning
as a tool to refine PM2.5 prediction, facilitating more accurate health risk assessments and policy-making for air quality
management in future studies.
Air pollution in Jos, Nigeria, is concerning due to a variety of anthropogenic causes which expose residents to possible respiratory health risks. Good emission source data and an understanding of all elements connected to air pollution is the foundation for successful pollution abatement. The study established a model for crosswind-integrated concentrations by solving the advection-diffusion equation using the reducible and irreducible techniques and utilizes it to forecast the concentration of PMX pollutants released from a stack in Jos, Nigeria. Data was collected from the Grand Cereals environment using a Handheld Portable Particle Counter for PMx with model number CW-HAT 200 for a year. High values of fine particulates recorded in the study are worrisome because they represent a threat to human health. Moreover, the monitored and modeled results evidenced a higher risk for human health in specific points, particularly areas less than 100 m away from the stack which is seen as deriving from the stack emissions. Electrostatic precipitators or mist collectors can be installed to reduce the PMX emissions and its impact on human health. We proposed that the boiler stack be replaced with a taller one and that people living and working near the industry wear a nasal mask to mitigate inhaling dangers. The model performs better in estimating PM2.5 concentrations under unstable conditions and is recommended for PM2.5 monitoring.
A sequential extraction guideline and protocol procedures were applied to specify and analyze major and trace elements, and water-soluble inorganic ions in size-separated atmosphere particulate matter. Quality control and quality of analysis were assured using standard reference materials and standards like NIST, USA. Enrichment of various elements was estimated. The enrichment factor of Co, Cu, Br, As, Zn, and H were found to be 5–150, indicating that these elements originate from sources of anthropogenic emission. A higher enrichment factor of N and Se in PM2.5 was also observed and can be attributed to industrial sources such as coal-related industry and coal storage areas near the monitoring station. The high correlation of NO3− with Cl−, F−, NO2−, SO42−, and Mg2+ indicates that these ions are likely to be originating from the same source, such as biomass burning.
Tropospheric anthropogenic aerosols contribute the second-largest forcing to climate change, but with high uncertainty owing to their spatio-temporal variability and complicated optical properties. In this Review, we synthesize understanding of aerosol observations and their radiative and climate effects. Aerosols offset about one-third of the warming effect by anthropogenic greenhouse gases. Yet, in regions and seasons where the absorbing aerosol fraction is high — such as South America and East and South Asia — substantial atmospheric warming can occur. The internal mixing and the vertical distribution of aerosols, which alters both the direct effect and aerosol–cloud interactions, might further enhance this warming. Despite extensive research in aerosol–cloud interactions, there is still at least a 50% spread in total aerosol forcing estimates. This ongoing uncertainty is linked, in part, to the poor measurement of anthropogenic and natural aerosol absorption, as well as the little-understood effects of aerosols on clouds. Next-generation, space-borne, multi-angle polarization and active remote sensing, combined with in situ observations, offer opportunities to better constrain aerosol scattering, absorption and size distribution, thus, improving models to refine estimates of aerosol forcing and climate effects. Atmospheric aerosols alter Earth’s radiation balance and serve as cloud condensation nuclei, but their climate forcing potential is poorly understood. This Review describes the occurrence of aerosols in the atmosphere, assesses the known impact on climate and proposes approaches to further constrain their climate effects. Climate models indicate at least a 30% uncertainty in aerosol direct forcing and 100% uncertainty in indirect forcing due to aerosol–cloud interactions.The amount of aerosol light scattering and absorption, expressed as the aerosol single-scattering albedo parameter, is critical in affecting both aerosol radiation interaction and aerosol–cloud interactions.Current satellite sensors cannot provide global-scale 3D single-scattering albedo measurements. Future observational efforts should combine satellite-based, multi-angle polarization sensors and high-spectral-resolution lidars with international aircraft and surface in situ observation networks.Direct comparison of radiation properties observed by satellites with those derived from climate models that assimilate aerosol parameters will improve the understanding of aerosol microphysical properties.Future work should investigate the mechanisms underlying aerosol–cloud interactions, especially the adjustment of cloud fraction and water for warm clouds and the microphysical processes in ice and mixed-phase clouds. Climate models indicate at least a 30% uncertainty in aerosol direct forcing and 100% uncertainty in indirect forcing due to aerosol–cloud interactions. The amount of aerosol light scattering and absorption, expressed as the aerosol single-scattering albedo parameter, is critical in affecting both aerosol radiation interaction and aerosol–cloud interactions. Current satellite sensors cannot provide global-scale 3D single-scattering albedo measurements. Future observational efforts should combine satellite-based, multi-angle polarization sensors and high-spectral-resolution lidars with international aircraft and surface in situ observation networks. Direct comparison of radiation properties observed by satellites with those derived from climate models that assimilate aerosol parameters will improve the understanding of aerosol microphysical properties. Future work should investigate the mechanisms underlying aerosol–cloud interactions, especially the adjustment of cloud fraction and water for warm clouds and the microphysical processes in ice and mixed-phase clouds.
Although air pollution in Ghana is ranked number one in environmental health threats to public health and sixth to cause of deaths, routine monitoring is rare. This paper presents fourteen years (2005-2018) assessment of aerosol optical depth (AOD) at 3 km resolution from MODIS Aqua and Terra satellites to ascertain the Spatio-temporal and seasonal distribution of aerosols over Ghana and its major cities. The MODIS AOD at 3 km were validated against ground-based Aerosol Robotic Network (AERONET) AODs to ascertain the suitability of the MODIS 3 km data for air quality application in the region. The contribution of distant aerosols to city aerosol loadings was also assessed with Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) backscatter model. A moderate-high aerosol burden (AODs ∼ 0.50) was observed over Ghana with a significant contribution from the pre-monsoon season. City centres of Takoradi and Kumasi showed higher aerosol loads (AODs ∼ 0.80) than Accra and Tamale. The HYSPLIT model showed that distant or transported aerosol sources to the city centres were of both marine and land generated origins. Linear regression analysis between MODIS AOD and AERONET AOD showed a reasonably good correlation of ∼ 0.60 for Aqua and Terra. From the validation analysis, both Aqua and Terra satellites can be used for air quality monitoring over Ghana; however, more ground research must be conducted to ascertain better aerosol model assumptions for the region.
The spate of increased air pollution in the study area is a source of concern. In this research, we examine the spatial distribution of atmospheric aerosol and its danger to the life form that resides therein. Fifteen years primary (aerosol optical depth) dataset was obtained from the Multi-angle Imaging Spectro-Radiometer (MISR). The secondary datasets that was generated from the primary data were aerosol loading, particles sizes, Angstrom parameter and the statistics of the primary dataset. It was observed that if not controlled, the life form in the research area may be under unimaginable danger in the near future. Hence, industrialization projects would require the dataset for environmental assessment before citing industry in the geographical area.
The strategic location of the AERONET site (Ilorin) makes it possible to obtain information on several aerosol types and their radiative effects. The strong reversal of wind direction occasioned by the movement of the ITCZ during the West Africa Monsoon (WAM) plays a major role in the variability of aerosol nature at this site. Aerosol optical depth (AOD) (675 nm) and Angstrom exponent (AE) (440-870 nm) with 1st and 99th percentile values of 0.08 and 2.16, and 0.11 and 1.47, respectively, confirms the highly varying nature of aerosol at this site. Direct radiative forcing (DRF) and radiative forcing efficiency (RFE) of aerosol as retrieved from the AERONET sun-photometer measurements are estimated using radiative transfer calculations for the period 2005-2009 and 2011-2015. The DRF and RFE of dominant aerosol classes - desert dust (DD), biomass burning (BB), urban (UB) and gas flaring (GF) - have been estimated. Median (±standard deviation) values of DRF at top-of-atmosphere (TOA) for the DD, BB, UB and GF aerosol classes are -27.5±13.2 Wm−2, -27.1±8.3 Wm−2, -11.5±13.2 Wm−2 and -9.6±8.0 Wm−2, respectively. While that of RFE for DD, BB, UB and GF aerosol classes are -26.2±4.1 Wm−2δ−1, -35.2±4.6 Wm−2δ−1, -31.0±8.4 Wm−2δ−1 and -37.0±10.3 Wm−2δ−1, respectively. The DD aerosol class showed the largest DRF but the smallest RFE, arguably, due to the high SSA and asymmetry factor values for this aerosol type. Its smallest AOD notwithstanding, the GF class could cause more perturbation to the Earth-Atmosphere system in the sub-region both directly and indirectly possibly due to the presence of black carbon and other co-emitted aerosol and the ageing of the GF aerosols. This study presents the first estimate of DRF for aerosols of gas flaring origin and shows that its radiative potential can be of similar magnitude to biomass burning, and urban aerosol in West Africa.
Background
Air pollution is involved in many pathologies. These pollutants act through several mechanisms that can affect numerous physiological functions, including reproduction: as endocrine disruptors or reactive oxygen species inducers, and through the formation of DNA adducts and/or epigenetic modifications. We conducted a systematic review of the published literature on the impact of air pollution on reproductive function.Eligible studies were selected from an electronic literature search from the PUBMED database from January 2000 to February 2016 and associated references in published studies. Search terms included (1) ovary or follicle or oocyte or testis or testicular or sperm or spermatozoa or fertility or infertility and (2) air quality or O3 or NO2 or PM2.5 or diesel or SO2 or traffic or PM10 or air pollution or air pollutants. The literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We have included the human and animal studies corresponding to the search terms and published in English. We have excluded articles whose results did not concern fertility or gamete function and those focused on cancer or allergy. We have also excluded genetic, auto-immune or iatrogenic causes of reduced reproduction function from our analysis. Finally, we have excluded animal data that does not concern mammals and studies based on results from in vitro culture. Data have been grouped according to the studied pollutants in order to synthetize their impact on fertility and the molecular pathways involved. Conclusion
Both animal and human epidemiological studies support the idea that air pollutants cause defects during gametogenesis leading to a drop in reproductive capacities in exposed populations. Air quality has an impact on overall health as well as on the reproductive function, so increased awareness of environmental protection issues is needed among the general public and the authorities.
Environmental security is totally relegated in countries of West Africa. The monitoring of the aerosols loading over Cotonou was the aim of this study. The outcome of our finding has salient links to food security, aviation and communication industry, thermal comfort and climate system of Benin. Cotonou is located on longitude 2.43°E and latitude 6.37°N. Fifteen years data were obtained from the multiangled spectro-reflectometry (MISR). The aerosol loading was monitored using analytical and statistical techniques. The aerosols retention over Cotonou was high in 2000 (69.91%), 2008 (72%) and 2013 (42.45%). This means that there is the possibility of higher rising sea levels and exposure to coastal erosion due to a twisted cloud formation.
The optical properties and chemical composition of PM1.0 particles in a suburban environment (Huairou) near the mega-city of Beijing were measured during the HOPE-J3A (Haze Observation Project Especially for Jing-Jin-Ji Area) field campaign. The campaign covered the period November 2014 to January 2015 during the winter coal heating season. The average values and standard deviations of the extinction, scattering, absorption coefficients, and the aerosol single scattering albedo (SSA) at λ = 470 nm during the measurement period were 201 ± 240, 164 ± 202, 37 ± 43 Mm-1, and 0.80 ± 0.08, respectively. The average values for the real and imaginary components of the effective complex refractive index (CRI) over the campaign were 1.40 ± 0.06 and 0.03 ± 0.02, while the average mass scattering and absorption efficiencies (MSE and MAE) of PM1.0 were respectively 3.6 and 0.7 m2 g-1. Highly time-resolved air pollution episodes clearly show the dramatic evolution of the PM1.0 size distribution, extensive optical properties (extinction, scattering, and absorption coefficients) and intensive optical properties (single scattering albedo and CRI) during haze formation, development and decline. Time periods were classified into three different pollution levels (clear, slightly polluted, and polluted) for further analysis. It was found that: (1) The relative contributions of organic and inorganic species to observed aerosol composition changed significantly from clear to polluted days: the organic mass fraction decreased from 50% to 43% while the proportion of sulfates, nitrates, and ammonium increased strongly from 34% to 44%. (2) Chemical apportionment of extinction, calculated using the IMPROVE algorithm, tended to underestimate the extinction compared to measurements. Agreement with measurements was improved by modifying the parameters to account for enhanced absorption by EC. Organic mass was the largest contributor (52%) to the total extinction of PM1.0, while EC, despite its low mass concentration of ca. 4%, contributed about 17%, to extinction. When the air quality deteriorated, the contribution of nitrate aerosol increased significantly (from 15% on clear days to 25% on polluted days). (3) Under polluted conditions, the average mass absorption efficiencies (MAE) of elemental carbon (EC) were up to 4 times as large as the reference MAE value for freshly generated black carbon (BC). The temporal pattern of MAE values was similar to that of the OC/EC ratio, suggesting that non-BC absorption from secondary organic aerosol (SOA) also contributes to particle absorption.
The optical properties and chemical composition of PM1.0 (particulate with an aerodynamic diameter of less than 1.0 μm) particles in a suburban environment (Huairou) near the mega-city Beijing were measured during the HOPE-J3A (Haze Observation Project Especially for Jing-Jin-Ji Area) field campaign. The campaign covered the period November 2014 to January 2015 during the winter coal heating season. The average and standard deviations for the extinction, scattering, absorption coefficients, and the aerosol single scattering albedo (SSA) at λ = 470 nm during the measurement period were 201 ± 240, 164 ± 202, 37 ± 43 Mm-1, and 0.80 ± 0.08, respectively. The mean mass scattering (MSE) and absorption (MAE) efficiencies were 4.77 ± 0.01 and 0.87 ± 0.03 m2g-1, respectively. Highly time-resolved air pollution episodes clearly show the dramatic evolution of the PM1.0 size distribution, extensive optical properties (extinction, scattering, and absorption coefficients) and intensive optical properties (single scattering albedo and complex refractive index) during haze formation, development and decline. Time periods were classified into three different pollution levels (clear, slightly polluted, and polluted) for further analysis. It was found that: (1) The diurnal patterns of the aerosol extinction, scattering, absorption coefficients, and SSA differed for the three pollution classes. (2) The real and imaginary part of complex refractive index (CRI) increased, while the SSA decreased from clear to polluted days. (3) The relative contributions of organic and inorganic species to observed aerosol composition changed significantly from clear to polluted days: the organic mass fraction decreased (50 to 43 %) while the proportion of sulfates, nitrates, and ammonium increased strongly (34 to 44 %). (4) The fractional contribution of chemical components to extinction coefficients was calculated by using the modified IMPROVE algorithm. Organic mass was the largest contributor (58 %) to the total extinction of PM1.0. When the air quality deteriorated, the change of the relative contribution of sulfate aerosol to the total extinction was small, but the contribution of nitrate aerosol increased significantly (from 17 % on clear days to 23 % on polluted days). (5) The observed mass scattering efficiencies increased consistently with the pollution extent, however, the observed mass absorption efficiencies increased consistently with increasing mass concentration in slightly pollution conditions, but decreased under polluted conditions.
A study of the long-term variability; trend and characteristics of visibility in four zones of Nigeria was carried out. Visibility and other meteorological data from NOAA-NCDC and aerosol index data over Nigeria during 1984–2013 are analyzed using time series and simple regression model. There are significant decreasing trends for every region and season during the 30-years period; the fluctuations exhibited nearly similar pattern. The 30-year mean visibilities for the four zones (Sahel; North Central; Southern; and Coastal) were 13.8 ± 3.9; 14.3 ± 4.2; 13.6 ± 3.5 and 12.8 ± 3.1 km with decreasing trends at the rates of 0.08; 0.06; 0.02 and 0.02 km/year. In all the zones; visibilities were better in summer while worse in Harmattan (dry season). During summer visibility was best in Sahel and North-central; however; in Harmattan visibility was best in southern and coastal zones. It was best between May and June (17.6; 18.9; 16.6 and 15.1 km) with a second peak in September. The 30-year seasonal averages were 16.2 ± 2.1; 16.8 ± 2.4; 15.4 ± 1.8 and 14.0 ± 2.2 km in summer; and 10.2 ± 2.5; 10.9 ± 2.9; 11.0 ± 3.3 and 11.4 ± 3.0 km in Harmattan for the respective zones. Sahel and North Central had the worse visibility reduction during Harmattan compared with Southern and coastal areas. An analysis based on simple regression equation reveals a strong and negative relationship between visibility on one hand; AI; and AOD on the other hand. The analysis also discusses the variability regarding the frequency of occurrence of a dust storm; dust haze; and good visibility over the period of study.
Atmospheric aerosol is a major health-impairment issue in Malaysia especially during southeast monsoon period (June-September) due to the active open burning activities. However, hazy days were an issue in Penang, Malaysia during March, 2014. Haze intruded Penang during March and lasted for a month except for the few days after rain.
Rain
water had washed out the aerosols from the atmosphere. Therefore, this study intends to analyse the aerosol profile and the optical properties of aerosol during this haze event and after rain. Meanwhile, several days after the haze event (during April, 2014) were also analyzed for comparison purposes. Additionally, the dominant aerosol type (i.e., dust, biomass burning, industrial and urban, marine, and mixed aerosol) during the study period was identified according to the scattering plots of the aerosol
optical depth (AOD) against the Angstrom exponent.
A series of tables and charts is presented from which the atmospheric transmittance between any two points in the terrestrial atmosphere can be determined. This material is based on a set of five atmospheric models ranging from tropical to arctic and two aerosol models. A selected set of laser frequencies has been defined for which monochromatic transmittance values have been given. For low resolution transmittance predcition, a series of charts has been drawn providing the capability for predicting transmittance at a resolution of 20 wave-numbers. Separate sections are included on scattered solar radiation, infrared emission, refractive effects, and attenuation by cloud and fog. This third edition differs from the others in that the low resolution spectral curves for the uniformly mixed gases and in the short wavelength region for water vapor have been revised, providing some overall improvement in accuracy; and more importantly, an appendix has been added providing model data and equivalent sea level path data for the U.S. Standard Atmosphere, 1962.
A series of tables and charts is presented from which the atmospheric transmittance between any two points in the terrestrial atmosphere can be determined. This material is based on a set of five atmospheric models ranging from tropical to arctic and two aerosol models. A selected set of laser frequencies has been defined for which monochromatic transmittance values have been given. For low resolution transmittance prediction, a series of charts has been drawn providing the capability for predicting transmittance at a resolution of 20 wavenumbers. Separate sections are included on scattered solar radiation, infrared emission, refractive effects, and attenuation by cloud and fog.
1] Direct and semidirect radiative effects of biomass burning aerosols from southern African fires during July–October are investigated using 20 year runs of the Community Atmospheric Model (CAM) coupled to a slab ocean model. Aerosol optical depth is constrained using observations in clear skies from Moderate Resolution Imaging Spectroradiometer (MODIS) and for aerosol layers above clouds from Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). Over the ocean, where the aerosol layers are primarily located above cloud, negative top of atmosphere (TOA) semidirect radiative effects associated with increased low cloud cover dominate over a weaker positive all‐sky direct radiative effect (DRE). In contrast, over the land where the aerosols are often below or within cloud layers, reductions in cloud liquid water path (LWP) lead to a positive semidirect radiative effect that dominates over a near‐zero DRE. Over the ocean, the cloud response can be understood as a response to increased lower tropospheric stability (LTS) which is caused both by radiative heating in overlying layers and surface cooling in response to direct aerosol forcing. The marine cloud changes are robust to changes in the cloud parameterization (removal of the hard‐wired dependence of clouds on LTS), suggesting that they are physically realistic. Over land, decreased LWP is consistent with weaker convection driven by increased static stability. Over the entire region the overall TOA radiative effect from the biomass burning aerosols is almost zero due to opposing effects over the land and ocean. However, the surface forcing is strongly negative, which leads to a reduction in precipitation and also a reduction in sensible heat flux. The former is primarily realized through reductions in convective precipitation on both the southern and northern flanks of the convective precipitation region spanning the equatorial rain forest and the Intertropical Convergence Zone (ITCZ) in the southern Sahel. The changes are consistent with the low‐level aerosol‐forced cooling pattern. The results highlight the importance of semidirect radiative effects and precipitation responses for determining the climatic effects of aerosols in the African region.
Occurrence, distribution, ecological risk and health risk of chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), arsenic (As) and cadmium (Cd) in PM2.5 of indoor dusts from Xi’an were determined. All the target elements were detected in the samples, and the maximum Cr, Mn, Ni, Cu, Zn, Pb, As and Cd contents in PM2.5 of dusts were 458, 1005, 115, 604, 2845, 1778, 122.6, and 21.1 mg/kg, respectively. Human activities, industrial produce and traffic could be the main reason for the detection of heavy metals in PM2.5. Cd exhibited significantly high potential ecological risk, which suggested that more attention should be paid to the ecological and environmental effects of Cd pollution. Health risk analysis shows that ingestion of dust particles is the route of exposure for metals in dust, followed by dermal adsorption and inhalation. For children, hazard indexes (HIs) for metals As and Pb were lager than 1, indicating the adverse non-carcinogenic risk for children. Overall, this study provides fundamental information regarding the occurrence, distribution, ecological risk and health risk of heavy metals, which could be helpful for further investigating the health risks of heavy metals in atmospheric environments.
In this study, we derived an analytical solution from the Gaussian approach and used it to estimate or predict the concentration of gaseous pollutants (CO and NO2) emitted from an industrial stack in northwestern Nigeria. The model results were compared with experimental data collected from the Terytex industry, Nigeria in Kano city using Altair 5X multi-gas detector for one year. The device is a portable handheld digital gas sensor meter that determines the concentrations of up to five gases simultaneously. The dispersion pattern of the pollutants was also studied by considering the effects of some parameters such as stack height, stack exit velocity, stack emission rate, temperature, solar radiation, wind speed, and direction. The measured and modeled averaged results ranged from 20.0-52.0 μg/m³ for NO2 and 8.0-16.0 μg/m³ for CO which are within the World Health Organization guideline and Nigeria Ambient Air Quality Standards except for CO values which were at some points higher than the set limits of (11.4 μg/m³). Statistical tools were also applied to test the model derived, and our findings revealed that the applied model was very useful under neutral conditions and in predicting the gaseous pollutants. We recommended that the concentration levels of CO and NO2 emissions control through complete combustion or industrial gas absorbers and the use of low-NOX burner (LNB) that operate at cooler temperatures to minimize the formation of thermal NOX. This will eliminate the consequences of effects on biological systems.
The optical properties of aerosols are investigated using multi-year analysis from the Ilorin AERONET site (8.320° N, 4.340° E) in Nigeria, in tropical West Africa. Characterization at five wavelengths (440, 550, 675, 870 and 1020 nm) were carried out to investigate the absorption and scattering tendencies of aerosol properties at multi-timescale. Results show large aerosol optical thickness (AOT) at 550 nm in a mixed aerosol load with 74% coarse mode dominance and 24% fine mode particles densely distributed in the dry-cold/Harmattan season (DJF) and sparsely distributed in the wet season (June–Oct). The volume size distribution (VSD) pattern shows higher variations and dominance for the coarse mode in the dry season than for the accumulation mode. The Ångström exponent (AE) α and τ550 show regular variations, with seasonal averaged maximum α > 1 and τ550 peak at ∼ 1.0. Values of α > 1 were observed in wet seasons; ∼1.1 (Aug), 1.04 (Sep). Averaged single scattering albedo (SSA) is confined to values between 0.83 and 0.97, with the highest values in October and lowest values in DJF due to biomass burning (BB) emissions mixed with transported desert dust that are composed of iron oxides (hematite) absorbing mineral. Seasonal ϖ0 increases with increasing wavelength and absorption was found to be the highest at 440 nm, with a total absorption of 0.16. The asymmetry parameter g shows minor interannual variations. The highest value of >0.70 was found at the shortest wavelength (440 nm), and was found to decrease as wavelengths increased. The real part of the refractive index (RR) ranges between 1.17 and 1.44 depending on seasons, and the imaginary part of the refractive index (RI) shows higher absorption for dry season (0.009).
A large number of processes are involved in the chain from emissions of aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those processes are manifest in a number of relationships that can be expressed as factors dlnX/dlnY driving aerosol effects on cloud radiative forcing. These factors include the relationships between cloud condensation nuclei (CCN) concentration and emissions, droplet number and CCN concentration, cloud fraction and droplet number, cloud optical depth and droplet number, and cloud radiative forcing and cloud optical depth. The relationship between cloud optical depth and droplet number can be further decomposed into the sum of two terms involving the relationship of droplet effective radius and cloud liquid water path with droplet number. These relationships can be constrained using observations of recent spatial and temporal variability of these quantities. However, we are most interested in the radiative forcing since the preindustrial era. Because few relevant measurements are available from that era, relationships from recent variability have been assumed to be applicable to the preindustrial to present-day change. Our analysis of Aerosol Comparisons between Observations and Models (AeroCom) model simulations suggests that estimates of relationships from recent variability are poor constraints on relationships from anthropogenic change for some terms, with even the sign of some relationships differing in many regions. Proxies connecting recent spatial/temporal variability to anthropogenic change, or sustained measurements in regions where emissions have changed, are needed to constrain estimates of anthropogenic aerosol impacts on cloud radiative forcing.
Different aspects of visibility degradation problems in Brisbane were investigated through concurrent visibility monitoring and aerosol sampling programs carried out in 1995. The relationship between the light extinction coefficients and aerosol mass/composition was derived by using multiple linear regression techniques. The visibility properties at different sites in Brisbane were found to be correlated with each other on a daily basis, but not correlated with each other hour by hour. The cause of scattering of light by moisture (bsw) was due to sulphate particles which shift to a larger size under high-humidity conditions. The scattering of light by particulate matter (bsp) was found to be highly correlated with the mass of fine aerosols, in particular the mass of fine soot, sulphate and non-soil K. For the period studied, on average, the total light extinction coefficient (bext) at five sites in Brisbane was 0.65×10−4 m−1, considerably smaller than those values found in other Australian and overseas cities. On average, the major component of bext is bsp (49% of bext), followed by bap (the absorption of light, mainly by fine soot particles, 28%), bsg (Rayleigh scattering, 20%) and bsw (3%). The absorption of light by NO2 (bag) is expected to contribute less than 5% of bext. On average, the percentage contribution of the visibility degrading species to bext (excluding bag) were: soot (53%), sulphate (21%), Rayleigh scattering (20%), non-soil K (2%) and humidity (3%). In terms of visibility degrading sources, motor vehicles (including soot and the secondary products) are expected to contribute more than half of the bext (excluding bag) in Brisbane on average, followed by secondary sulphates (17%) and biomass burning (10%).
Characteristics of visual air quality in Seoul were investigated during the fall of 1993. The total extinction coefficient, bext the particle light scattering coefficient, bsp, and the particle mass size distribution were measured using a transmissometer, a nephelometer and a cascade impactor, respectively. Also PM1, PM3 and PM10 particles were collected and analyzed for their ionic concentrations. The smog characteristics were also estimated by using a Mie theory based model. Measured and estimated light extinction budgets agree to each other within 10%. According to measurements, the daily average bext were 0.791 × 10−3 and 0.297 × 10−3 m−1 during the smoggy and clear period, respectively. Also bsp contributed 79.4 and 55.2% to bext during the smoggy and clear period, respectively, showing that particle scattering is the dominant factor in light extinction during the smog episode. The major variables that affect smog phenomena in Seoul are mass loadings of fine particle fraction (Dp < 2.98 μm), concentrations of sulfate and nitrate in fine particles, and relative humidity. The particle mass size distribution shows typical bimodal peaks, one of which is at about 0.8 μm and the other at about 5.0 μm of the mean diameter during both periods. Particulate sulfate and nitrate are more concentrated in the fine particle size fraction during the smoggy period than in the clear period. The effects of relative humidity are thought to influence the extinction and scattering efficiencies of particle species through changing the particle size.
The contribution of aerosols to light extinction at Meadview, AZ, during summer 1992 was estimated using Mie theory and size-resolved aerosol chemical measurements. Sulfate particle size increased as a function of relative humidity. Twelve-hour average light scattering was estimated to within 15%. Sulfate was the most abundant chemical component in the fine aerosol fraction. On average, Rayleigh scattering, coarse particles, and fine sulfates contributed 39, 21, and 19% to total light extinction. Average estimated light scattering was largely insensitive to assumptions about mixing state, degree of sulfate neutralization and organic carbon water uptake properties. It was estimated that a reduction of Mohave Power Plant (MPP) SO2 emissions corresponding to a contribution of 19% to ambient sulfate would have resulted in a decrease in total light extinction of between 3.3 and 5.3%.
Recent developments in atmospheric aerosol measurements are reviewed. The topics included complement those covered in the recent review by Chow (JAWMA 45: 320–382, 1995) which focuses on regulatory compliance measurements and filter measurements of particulate composition. This review focuses on measurements of aerosol integral properties (total number concentration, CCN concentration, optical coefficients, etc.), aerosol physical chemical properties (density, refractive index, equilibrium water content, etc.), measurements of aerosol size distributions, and measurements of size-resolved aerosol composition. Such measurements play an essential role in studies of secondary aerosol formation by atmospheric chemical transformations and enable one to quantify the contributions of various species to effects including light scattering/absorption, health effects, dry deposition, etc. Aerosol measurement evolved from an art to a science in the 1970s following the development of instrumentation to generate monodisperse calibration aerosols of known size, composition, and concentration. While such calibration tools permit precise assessments of instrument responses to known laboratory-generated aerosols, unquantifiable uncertainties remain even when carefully calibrated instruments are used for atmospheric measurements. This is because instrument responses typically depend on aerosol properties including composition, shape, density, etc., which, for atmospheric aerosols, may vary from particle-to-particle and are often unknown. More effort needs to be made to quantify measurement accuracies that can be achieved for realistic atmospheric sampling scenarios. The measurement of organic species in atmospheric particles requires substantial development. Atmospheric aerosols typically include hundreds of organic compounds, and only a small fraction (∼10%) of these can be identified by state-of-the-art analytical methodologies. Even the measurement of the total particulate organic carbon mass concentration is beset by difficulties including the unknown extent of evaporative losses during sampling, adsorption of gas-phase organic compounds onto sampling substrates, and the unknown relationship between carbon mass and mass of the particulate organics. The development of improved methodologies for such measurements should be a high priority for the future. Mass spectrometers that measure the composition of individual particles have recently been developed. It is not clear that these instruments will provide quantitative information on species mass concentrations, and more work is needed to routinely interpret the vast quantities of data generated during field sampling. Nevertheless, these instruments substantially expand the range of atmospheric aerosol issues that can be explored experimentally. These instruments represent the most significant advance in aerosol instrumentation in recent years.
The absorption and scattering of light by small particles is discussed
in terms of basic theory, optical properties of bulk matter, and optical
properties of particles. The subjects addressed include: electromagnetic
theory, absorption and scattering by an arbitrary particle and by a
sphere, particles small compared with the wavelength, the Rayleigh-Gans
theory, geometrical optics, and miscellaneous particles. Also considered
are: classical theories of optical constants, measured optical
properties, extinction, surface modes in small particles, the angular
dependence of scattering, and applications.
The Southeastern Aerosol and Visibility Study (SEAVS) was carried out to characterize the size-dependent composition, thermodynamic properties, and optical characteristics of the ambient atmospheric particles. Using statistical techniques, an attempt is made to compare measurements of scattering at ambient conditions and as functions of relative humidity to theoretical predictions of scattering. A new analysis technique is introduced, that relies on measurements of scattering as a function of relative humidity to develop actual estimates of f(RH) curves.
Visibility data collected from Kaohsiung City, Taiwan, for the past two decades indicated that the air pollutants have significantly degraded visibility in recent years. During our study period, the seasonal mean visibilities in spring, summer, fall, and winter were only 5.4, 9.1, 8.2, and 3.4 km, respectively. To ascertain how urban aerosols influence the visibility, we conducted concurrent visibility monitoring and aerosol sampling in 1999 to identify the principal causes of visibility impairments in the region. In this study, ambient aerosols were sampled and analyzed for 11 constituents, including water-soluble ions and carbon materials, to investigate the chemical composition of Kaohsiung aerosols. Stepwise regression method was used to correlate the impact of aerosol species on visibility impairments. Both seasonal and diurnal variation patterns were found from the monitoring of visibility. Our results showed that light scattering was attributed primarily to aerosols with sizes that range from 0.26 to 0.90 pm, corresponding with the wavelength region of visible light, which accounted for approximately 72% of the light scattering coefficient. Sulfate was a dominant component that affected both the light scattering coefficient and the visibility in the region. On average, (NH4)2SO4, NH4NO3, total carbon, and fine particulate matter (PM2.5)-remainder contributed 53%, 17%, 16%, and 14% to total light scattering, respectively. An empirical regression model of visibility based on sulfate, elemental carbon, and humidity was developed, and the comparison indicated that visibility in an urban area could be properly simulated by the equation derived herein.
Igbawua T (2020) Fine Particulate Matter and Heavy Metals Pollution Status in Ambient Air of Some Selected Industrial Sites in Northern Nigeria
- T J Ayua
- A A Tyovenda
- T Sombo
- E V Tikyaa
- TJ Ayua
Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability
- S J Ghan
- M Wang
- S Zhang
- S Ferrachat
- A Gettleman
- J Griesfeller
- Z Kipling
- U Lohmann
- H Morrison
- D Neubauer
- D G Partridge
- P Stier
- T Takemura
- H Wang
- K Zhang
Ghan SJ, Wang M, Zhang S, Ferrachat S, Gettleman A, Griesfeller J,
Kipling Z, Lohmann U, Morrison H, Neubauer D, Partridge DG,
Stier P, Takemura T, Wang H, Zhang K (2016) Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing
using present-day spatiotemporal variability. Proc Natl Acad Sci
113:5804-5811. https:// doi. org/ 10. 1073/ pnas. 15140 36113,1012
Fine Particulate Matter and Heavy Metals Pollution Status in Ambient Air of Some Selected Industrial Sites in Northern Nigeria
- T J Ayua
- A A Tyovenda
- T Sombo
- E V Tikyaa
- T Igbawua
Ayua TJ, Tyovenda AA, Sombo T, Tikyaa EV, Igbawua T (2020) Fine
Particulate Matter and Heavy Metals Pollution Status in Ambient
Air of Some Selected Industrial Sites in Northern Nigeria. J Geosci Environ Prot 8:1-13. https:// doi. org/ 10. 4236/ gep. 2020. 8800
Particulate Pollution in Korhogo and Abidjan (Cote d'Ivoire) during the Dry Season
- S Gnamien
- V Yoboué
- C Liousse
- M Ossohou
- S Keita
- J Bahino
- S Siélé
- L Diaby
Gnamien S, Yoboué V, Liousse C, Ossohou M, Keita S, Bahino J,
Siélé S, Diaby L (2020) Particulate Pollution in Korhogo and
Abidjan (Cote d'Ivoire) during the Dry Season. Aerosol Air Qual
Res 21(1):200201. https:// doi. org/ 10. 4209/ aaqr. 200226
Simulation of fine particulate matter dispersion from the Grand Cereals Industry Jos
- T J Ayua
- A A Tyovenda
- E V Tikyaa
- S Balarebe
Ayua TJ, Tyovenda AA, Tikyaa EV, Balarebe S (2023) Simulation
of fine particulate matter dispersion from the Grand Cereals
Industry Jos, Nigeria Using a Modified Gaussian Plume Model.
- K Fosu-Amankwah
- Geq Bessardon
- E Quansah
- L K Amekudzi
- B J Brooks
- R Damoah
Fosu-Amankwah K, Bessardon GEQ, Quansah E, Amekudzi LK,
Brooks BJ, Damoah R (2021) Assessment of aerosol burden over
Ghana. Scie Afr 14:e00971
Emission plumes over West Africa contain a high proportion of organic material
- R W Fenn
- Jea Selby
- E Volz
- J S Garing
Max Planck Institute for Chemistry (2016) Emission plumes over West
Africa contain a high proportion of organic material. Press and
Public Relations, Johannes Gutenberg-Universität Mainz
McClatchey RA, Fenn RW, Selby JEA, Volz E, Garing JS (1972) Optical Properties of the Atmosphere, Rep. AFCRL-72-0497, 3rd Ed.,
Air Force Cambridge Research Laboratories, Bedford, MA.