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Coronavirus (COVID-19) has rapidly spread across many countries in pandemic proportions since the first case was reported in Hubei, China in December 2019. Understanding transmission, susceptibility and exposure risks is crucial for surveillance, control and response to the disease. Knowing the geographic distribution of health resource scarcity areas is necessary if a country is to adequately anticipate and prepare for the full impact of infections. We explored the potential to undertake a spatial risk assessment of an emerging pandemic under data scarcity in Eswatini. We used a set of socio-economic and demographic variables to identify epidemic risk prone areas in the country. Three risk zone levels for COVID-19 were identified in the country. The analysis showed that about 29% (320 818) of the population were located in the high risk zone and these were people who could potentially be infected with COVID-19 in the absence of mitigation measures. A majority of cases and deaths attributed to COVID-19 would likely remain unknown but our estimate could be used to gauge the full burden of the disease. Approximating and quantifying the number of people who may be potentially infected with COVID-19 remains impossible under data scarcity and limited healthcare capacity especially in sub-Saharan Africa. We provided an estimation method that could support the pandemic risk forecasting, preparedness and response measures in the midst of data scarcity. The resultant map products could be used to guide on-the-ground surveillance and response efforts., Highlights • About 321 000 people are located in the COVID-19 high risk zone in Eswatini. • A majority of COVID-19 cases and deaths are likely to remain unknown due to poor testing in Eswatini. • Minimizing movement from high risk zones to low risk areas could help control the spread of COVID-19.

Veld fires have become a frequent and devastating phenomena in the predominantly savanna ecosystems of the Kingdom of Eswatini. While fire damages have become more common and recurrent in recent years, their causes and impacts in the Kingdom of Eswatini are less understood, with very limited literature. This study aimed at filling up this existing information gap by investigating the causes, socio-economic and environmental impacts of veld fires, as well as highlighting the challenges and/or limitations in fire management and control in the Kingdom of Eswatini. The study used mixed methods approach to collect both primary and secondary data. These included household questionnaires and face-to-face interviews with key informants. The results showed that the major causes of fires are mainly anthropogenic, and these include arson and conflicts, controlled burning, ignorance of proper fire management practices, collision of electric cables, and acts of negligence, among others. Major impacts of veld fires in Eswatini were found to include disruption of rural (and urban) livelihoods, infrastructure damage, loss of biodiversity and destruction of important environmental resources, to mention but a few. The study concluded that fires contribute to biodiversity loss and that fires continue to be a major treat to the country’s economy. Lack of fire management resources is one contributing factor to the widespread fire damage in the country, while quantifying the direct economic loss resulting from fire remains a challenge due to lack of standardized fire damages data collection and reporting tools. The study recommended a development of a standardized tool for reporting fire damages, improvement of fire prevention and management, and development of an early warning system (in addition to capacity assessment of fire emergency operators) in an effort to improve fire management and to minimize fire-related damages in the country.

High resolution remotely sensed (RS) data products remain of interest in disease mapping studies. However, previous usage of such satellite-derived products had been limited by high costs. There is also unprecedented space activity characterized by prolific satellite launches for various purposes, the chief of which being land cover observation. Therefore, there is need for information availability on the type of data products obtainable from the captured satellite images in order to facilitate access and utilization. Clearly, the remote sensing landscape is changing with the advent of Unmanned Aerial Vehicle/drones and spatially explicit images being captured at relatively low costs. We conducted a review to find out which RS data products were accessible for disease mapping and epidemiology. Our aim was to document RS data products for disease mapping and to propose other such products that could be incorporated in disease mapping and epidemiology studies. In view of the fact that RS data products are rapidly evolving, image data of higher spatial and temporal resolutions in near-real time are already available to aid disease mapping. We presented a catalogue of indices from ecological studies that could be used as variables in disease mapping and epidemiology. Remotely sensed data products related to climate, meteorology, land use/cover, cartography and urban mapping are explored as potential indices for disease mapping. There remains a substantial amount of work to be conducted on the evaluation and validation of some of the indices presented in this study. Conversely, synergies between remote sensing experts and epidemiologists could be useful in the uptake and testing of some of the proposed RS data products presented in this work.

Riparian vegetation in the Okavango Delta has extensive economic, social and environmental benefits. However, despite its importance, it is threatened by changes in variation in hydrology, anthropogenic activities, and other environmental conditions. Some riparian vegetation communities may change rapidly in response to both long term and short term disturbances. Long term monitoring of riparian woodland vegetation can help reveal changes in these woodland species, enabling timeous management interventions. In this study we classified, mapped and conducted change detection analysis of the spatial extent of different communities of riparian woodland in the Okavango Delta. Woodland species were identified in the field and their percentage cover estimated. Agglomerative hierarchical cluster analysis in PC-ORD was used to classify woodland vegetation into four communities. These communities were Croton megalobotrys-Hyphaene petersiana, Vachellia erioloba-Gymnosporia senegalensis, Phoenix reclinata-Syzygium cordatum and Vachellia tortilis-Combretum imberbe. Multi response permutation procedures (MRPP) was used to test if there was any significant difference in plant species composition between different vegetation communities. MRPP showed that communities varied significantly (p

The study investigated plastic waste management practices in the rural households of the Kingdom of Eswatini using Zikhotheni and Zombodze Emuva communities as case study sites. The aim of the study was to investigate plastic waste management practices employed by rural households through the identification of the types of plastic waste generated, estimation of the average daily amount of generated plastics and establishing their management practices. A total of 109 households (54 in Zikhotheni and 55 in Zombodze Emuva) were selected using simple random sampling. A questionnaire (supplemented with an observation matrix) was used to collect data from the sampled population. Classification of the types of plastic generated and measurements of the amount of plastic waste produced per household were performed for two consecutive months (December 2018 and January 2019). The results revealed that the types of plastic waste generated by these two communities included: Polyethylene Terephathalate (PET), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low Density Polyethylene (LDPE), Poly propylene (PP), Polystyrene (PS), Expanded Polystyrene (EPS) and other plastic materials layered from other types. On average, it was found that a rural household generates about 15.9 ​g of plastic waste per day. Common waste management practices found included open burning, burying, reusing, disposing of plastics in backyard pit, indiscriminate disposal in the backyard, selling and recycling. The study concluded that most of the rural households are still using traditional methods of managing plastic waste, even though recommended plastic waste management practices such as reusing and recycling were found amongst some households in Zombodze Emuva.

Trace metal species emitted into the atmosphere from natural and anthropogenic sources can cause various health-related and environmental problems. Limited data exist for atmospheric trace metal concentrations in South Africa, which has the largest industrialised economy in Africa, with significant mining and metallurgical activities. A large fraction of these mineral assets is concentrated in the Bushveld Igneous Complex, with the western limb being the most exploited. To partially address this knowledge gap, atmospheric trace metals were collected in the western Bushveld Igneous Complex at Marikana in the North West Province. Diurnal PM 2.5 and PM 10 samples were collected for 1 year. A total of 27 trace metal species were determined. With the exception of Ni, none of the trace metals measured during the sampling period exceeded local or international air quality standard limit values. Total trace metal concentrations in the PM 10 fraction peaked during the dry months and were regularly washed out during the wet season. A less significant seasonal trend was observed for the trace metal concentrations in the PM 2.5 fraction; a finding attributed to a faster replenishment of smaller particles into the atmosphere after rain events. About 80% of the PM 10 trace metal levels measured occurred in the PM 2.5 fraction, while 40% or more of all metals emanated from the PM 2.5 fraction. This finding indicated a strong influence of anthropogenic sources. Four meaningful emission sources were determined from explorative principal component factor analysis: crustal, vanadium related, base metal related and ferrochromium related, which correlated well with the anticipated atmospheric trace metal sources in the region.

The South African savannah region is a complex environment of air pollution and natural emissions influenced by a strong seasonal cycle in biomass burning and strong precipitation. However, the scarcity of long-term observations means that the knowledge of controlling aerosol processes in this environment is limited. Here we use a recent dataset of 18 months of aerosol size distribution observations trying to understand the annual cycle of cloud condensation nuclei (CCN). Our observations show that the concentration of CCN-sized particles remains, in line with previous studies, high throughout the year with the highest concentrations during the dry winter and the lowest during the wet summer. During the wet season with reduced anthropogenic and biomass burning primary emissions, this pool of CCN is partly filled by boundary layer nucleation with subsequent growth. The enhanced importance of formation and growth during the wet season is addressed to increased biogenic activity together with enhanced free tropospheric removal decreasing the concentration of pre-existing CCN. During the dry season, while frequent new particle formation takes place, particle growth is reduced due to reduced condensing vapour concentrations. Thus in the dry season particles are not able to grow to sizes where they may act as CCN nearly as efficiently as during the wet season. The observations are compared to simulations by a global aerosol model GLOMAP. To our surprise, the global aerosol model utilized to explain the observations was not capable of re-producing the characteristics of particle formation and the annual CCN cycle, despite earlier good performance in predicting the particle concentrations in a number of diverse environments, including the South African savannah region. While the average yearly CCN concentrations of modelled CCN is close to observed concentrations, the characteristics of nucleation bursts and subsequent growth are not captured satisfactory by the model. Our sensitivity tests using different nucleation parameterizations and condensing organic vapour production rates show that neither of these is likely to explain the differences between observed and modelled nucleation and growth rates. A sensitivity study varying 28 modelling parameters indicates that the main uncertainties in the result are due to uncertainties in biomass burning emissions during the dry season, and anthropogenic sulphur emissions during the wet season, both in terms or emitted mass and particle sizes. The uncertainties appear to be mostly related to uncertainties in primary particle emissions, including the emissions variability not captured by monthly emission inventories. The results of this paper also highlights the fact that deficiencies in emissions estimates may result in deficiencies in particle production fluxes, while the end product such as modelled CCN concentration may be in line with observations.

We have analyzed one year (July 2006–July 2007) of measurement data from a relatively clean background site located in dry savannah in South Africa. The annual-median trace gas concentrations were equal to 0.7 ppb for SO2, 1.4 ppb for NOx, 36 ppb for O3 and 105 ppb for CO. The corresponding PM1, PM2.5 and PM10 concentrations were 9.0, 10.5 and 18.8 μg m−3, and the annual median total particle number concentration in the size range 10–840 nm was 2340 cm−3. During Easterly winds, influence of industrial sources approximately 150 km away from the measurement site was clearly visible, especially in SO2 and NOx concentrations. Of gases, NOx and CO had a clear annual, and SO2, NOx and O3 clear diurnal cycle. Atmospheric new-particle formation was observed to take place in more than 90% of the analyzed days. The days with no new particle formation were cloudy or rainy days. The formation rate of 10 nm particles varied in the range of 0.1–28 cm−3 s−1 (median 1.9 cm−3 s−1) and nucleation mode particle growth rates were in the range 3–21 nm h−1 (median 8.5 nm h−1). Due to high formation and growth rates, observed new particle formation gives a significant contribute to the number of cloud condensation nuclei budget, having a potential to affect the regional climate forcing patterns.

This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006–January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008–May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12–840 nm, 50–840 nm and 100–840 nm the median concentrations were 1856, 1278 and 698 particles cm−3 at Botsalano and 7805, 3843 and 1634 particles cm−3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration originates from regional wild fires, while at Marikana domestic heating in the informal settlements is the main source. Air mass history analysis for Botsalano identified four regional scale source areas in southern Africa and enabled the differentiation between fresh and aged rural background aerosol originating from the clean sector, i.e., western sector with very few large anthropogenic sources. Comparison to size distributions published for other comparable environments in Northern Hemisphere shows southern African savannah to have a unique combination of sources and meteorological parameters. The observed strong link between combustion and seasonal variation is comparable only to the Amazon basin; however, the lack of long-term observations in the Amazonas does not allow a quantitative comparison. All the data presented in the figures, as well as the time series of monthly mean and median size distributions are included in numeric form as a Supplement to provide a reference point for the aerosol modelling community.

South Africa has the largest industrialised economy in Africa, with significant mining and metallurgical activities. A large fraction of the South African mineral assets is concentrated in the Bushveld Igneous Complex (BIC), with the western limb being the most exploited. Because the majority of the world’s platinum is produced in the BIC, this area is also of international interest. There are some indications that the western BIC should be considered an air pollution hotspot; however, inadequate data exist to substantiate these claims scientifically. To partially address this knowledge gap, a comprehensive air quality monitoring station was operated for more than 2 years in this area. Meteorological parameters, trace gas concentrations and total mass concentration of particulate matter up to 10 µm in size (PM 10 ) were measured. Compared with South African and European ambient air quality standards, SO 2 , NO 2 and CO concentrations were generally acceptable. The major sources of SO 2 were identified as high-stack industry emissions, while household combustion from semi-formal and informal settlements was identified as the predominant source of NO 2 and CO. In contrast, O 3 exceeded the 8-h moving average more than 322 times per year. The main contributing factor was identified to be the influx of regional air masses, with high O 3 precursor concentrations. PM 10 exceeded the current South African 24-h standard 6.6 times per year, the future (2015) standard 42.3 times per year and the European standard more than 120 times per year. The main source of PM 10 was identified as household combustion from semi-formal and informal settlements. The findings clearly indicate that atmospheric O 3 and PM 10 levels in the western BIC need to be addressed to avoid negative environmental and human health impacts.

The South African savannah region is complex environment of air pollution and natural emissions influenced by a strong seasonal cycle in biomass burning and strong precipitation. However, the scarcity of long-term observations means that our knowledge of controlling aerosol processes in this environment is very poor. Here we use a new dataset of 18 months of aerosol observations to understand the factors that control aerosol properties, and in particular cloud condensation nuclei. We find that biomass burning produces a strong source of primary CCN-sized particles during the dry winter season. However, measured CCN-sized particle concentrations remain high during the wet summer season despite the lack of burning and high wet removal rates. We show that during the wet season, a substantial fraction of CCN-sized particles originate from boundary layer new particle formation, whereas primary sources dominate during the dry winter season. The large contribution of boundary layer nucleation to CCN concentrations during the wet season is found to be due to high particle formation and growth rates and low pre-existing particle concentration in the beginning of particle formation. Based on the estimated seasonal cycle of condensable sulphuric acid and organic vapours, higher growth rates during the wet season are attributed to vapours of biogenic origin. Global model results for this region have the same seasonal cycle in nuclei growth rates but the opposite cycle in particle formation rates, and both rates are much lower than observed. In contrast, the same model tends to capture the seasonal cycle in particle concentrations at many other global sites where nucleation is an important process. These results point to deficiencies in our understanding of biogenic emissions and the factors controlling nucleation and growth in such dynamic environments.

This study is based on 18 months (20 July 2006–5 February 2008) of continuous measurements of aerosol particle size distributions, air ion size distributions, trace gas concentrations and basic meteorology in a semi-clean savannah environment in Republic of South Africa. New particle formation and growth was observed on 69% of the days and bursts of non-growing ions/sub-10 nm particles on additional 14% of the days. The new particle formation and growth rates were among the highest reported in the literature for continental boundary layer locations; median 10 nm formation rate was 2.2 cm−3s−1 and median 10–30 nm growth rate 8.9 nm h−1. The median 2 nm ion formation rate was 0.5 cm−3s−1 and the median ion growth rates were 6.2, 8.0 and 8.1 nm h−1 for size ranges 1.5–3 nm, 3–7 nm and 7–20 nm, respectively. Three different approaches were used to study the origin of the formation and growth rates: seasonal variation, air mass history analysis and estimated sulphuric acid contribution to the growth. The growth rates had a clear seasonal dependency with minimum during winter and maxima in spring and late summer and the air mass history analysis indicated the highest formation and growth rates to be associated with the area of highest VOC (Volatile Organic Compounds) emissions rather than the highest estimated sulphuric acid concentrations. The relative contribution of estimated sulphuric acid to the growth rate was decreasing with increasing particle size and could explain more than 20% of the observed growth rate only for the 1.5–3 nm size range. The implication is that the sulphuric acid alone is not enough to explain the growth, but the highest growth rates seem to originate in VOC emissions following from biological activity. The frequency of new particle formation, however, increased nearly monotonously with the estimated sulphuric acid reaching 100% at H2SO4 concentration of 4×107cm−3, which suggests the formation and growth to be independent of each other.

Southern African savanna background environment lacks previous, continuous long-term combined sub-micrometer aerosol number concentration and gas measurements. We have build a mobile measurement trailer, which contains measurements of aerosol number size distributions 10-840 nm, positive and negative ion size distributions 0.4-40 nm, aerosol mass PM 10 , PM 2.5 , PM 1 , inorganic compound in PM 10 and PM 2.5 , gases like SO 2 , NO, NOx, CO, O 3 and basic meteorology. In addition, we measure periodically VOCs. The trailer is well- protected against thunder storms, electricity breaks and other typical problems. It is connected to internet via GPRS-modem. Preliminary results show that in a clean savanna environment, new particle formation takes place every sunny day, with relatively high nucleation rates and very high growth rates (up to 15 nm/h).