Correcting respirable photometric particulate measurements using a gravimetric sampling method

According to the National Environmental Management: Air Quality Act of 2004 people have the right to clean air and a healthy environment. Particulate matter (PM) emissions pose a significant health threat. Both indoor and ambient air pollution contribute to the burden of disease associated with poor air quality. This is particularly true within the South African setting where low income households make use of different solid fuels for heating and cooking purposes resulting in high levels of PM emissions. This paper focuses on the evaluation mass concentration measurements recorded by continuous photometric PM instruments within KwaDela, a low income settlement in Mpumalanga located on the South African Highveld. Thus, obtaining a photometric calibration factor for both the DustTrak Model 8530 and the SidePak AM510. Sampling took place during August 2014 for a period of seven days. The photometric and gravimetric instruments were collocated within the indoor environment of selected households. These instruments were all fitted with 10mm Dorr-Oliver Cyclone inlets to obtain the respirable (PM4) cut-point. The study found that both instruments tend to overestimate the indoor particulate mass concentrations when compared to the reference gravimetric method. The estimated photometric calibration factors for the DustTrak Model 8530 and SidePak AM510 are 0.14 (95%Cl: 0.09, 0.15) and 0.24 (95%Cl: 0.16, 0.30) respectively. The overestimation of the photometric measurements is rather significant. It is therefore important that the correction factors are applied to data collected in indoor environments prone to the combustion of solid fuels. The correction factors obtained from this and other studies vary as a result of the environment (ambient, indoor etc.) as well as the aerosol size fraction and the origin thereof. Thus, it is important to considered site specific calibration factors when implementing these photometric light-scattering instruments

Indoor and outdoor particulate matter concentrations on the Mpumalanga highveld – A case study

The household combustion of solid fuels, for the purpose of heating and cooking, is an activity practiced by many people in South Africa. Air pollution caused by the combustion of solid fuels in households has a significant influence on public health. People mostaffected are those considered to be the poorest, living in low-income settlements, where burning solid fuel is the primary source of energy. Insufficient data has been collected in South Africa to quantify the concentrations of particulate emissions that peopleare exposed to, especially the respirable fraction, associated with the combustion of solid fuels. The aim of this paper is to gain an understanding of the particulate matter (PM) concentrations a person living in a typical household in a low income settlement in theSouth African Highveld is exposed to. It also seeks to demonstrate that the use of solid fuels in the household can lead to indoor air pollution concentrations reaching levels very similar to ambient PM concentrations, which could be well in excess of the NationalAmbient Air Quality Standards, representing a major national public health threat. A mobile monitoring station was used in KwaDela, Mpumalanga to measure both ambient particulate concentrations and meteorological conditions, while a range of dust/particulate monitors were used for indoor and personal particulate concentration measurements. Indoor and personal measurements are limited to the respirable fraction (PM4) as this fraction contributes significantly to the negative health impacts. The sampling for this case study took place from 7-19 August 2014. Highest particulate matter concentrations were evident during the early mornings and the early evenings, when solid fuel burning activities were at their highest. Indoor and personal daily average PM4 concentrations did not exceed the 24h National Ambient PM2.5 Standard of 65 μg/m3 nor did they exceed the 24h National Ambient PM10 Standard of 75 μg/ m3. The outdoor PM2.5 concentrations were found to be below the standards for the duration of the sampling period. The outdoor PM10 concentrations exceeded the standards for one day during the sampling period. Results indicate that, although people in KwaDelamay be exposed to ambient PM concentrations that can be non-compliant to ambient standards, the exposure to indoor air, where solid fuel is burnt, may be detrimental to their health

Characterising the impact of rainfall on dustfall rates

Soil moisture increased the cohesion potential between particles, reducing the ability of the particle to be entrained. Dust suppression techniques are designed to increase soil moisture and therefore soil cohesion through the application of water or water-based chemicals to surfaces that have known potential for dust entrainment. Rainfall has the ability to act as a natural dust suppression mechanism; however, there is a paucity of literature on the actual effectiveness of rainfall in this regard. The ASTM D1739 methods for dustfall monitoring, commonly used in South Africa, and the National Dust Control Regulations (2013), both state that rainfall should be recorded when conducting dustfall monitoring. The rationale is that rainfall or the absence thereof, results in lower or higher dustfall rates, respectively. A suitable study site was identified in Mpumalanga, South Africa. This site had eight non-directional dustfall samplers in the near vicinity of an air quality monitoring station. Dustfall results from the eight samplers were analysed based on four scenarios, two that considers the presence of rainfall and two that consider the absence of rainfall. This analysis was further combined with wind speed data. This study, over a 24-month period indicates that there is no substantial evidence that above average rainfall will result in below average dustfall. This occurred for one month out of 24 months. Conversely, there is no consensus that the absence of rainfall will result in higher dustfall rates, which occurred cumulatively 30% of the time. Additional environmental and / or operational information may have a greater influence on dustfall compared to rainfall. Careful consideration should be taken to prevent misrepresentation of causational effects of rainfall on dustfall results. Management of dust should be undertaken through dust mitigation measures irrespective of the natural rainfall regime

Uncertainty of dustfall monitoring results

Fugitive dust has the ability to cause a nuisance and pollute the ambient environment, particularly from human activities including construction and industrial sites and mining operations. As such, dustfall monitoring has occurred for many decades in South Africa little has been published on the repeatability, uncertainty, accuracy and precision of dustfall monitoring. Repeatability assesses the consistency associated with the results of a particular measurement under the same conditions; the consistency of the laboratory isassessed to determine the uncertainty associated with dustfall monitoring conducted by the laboratory. The aim of this study was to improve the understanding of the uncertainty in dustfall monitoring; thereby improving the confidence in dustfall monitoring. Uncertainty of dustfall monitoring was assessed through a 12-month study of 12 sites that were located on the boundary of the study area. Each site contained a directional dustfall sampler, which was modified by removing the rotating lid, with four buckets (A, B, C and D) installed. Having four buckets on one stand allows for each bucket to be exposed to the same conditions, for the same period of time; therefore, should have equal amounts of dust deposited in these buckets. The difference in the weight (mg) of the dust recorded from each bucket at each respective site was determined using the American Society for Testing and Materials method D1739 (ASTM D1739). The variability of the dust would provide the confidence level of dustfall monitoring when reporting to clients

Towards the development of a GHG emissions baseline for the Agriculture, Forestry and Other Land Use (AFOLU) sector, South Africa

South Africa is a signatory to the United Nations Framework Convention on Climate Change (UNFCCC) and as such is required to report on Greenhouse gas (GHG) emissions from the Energy, Transport, Waste and the Agriculture, Forestry and Other Land Use (AFOLU) sectors every two years in national inventories. The AFOLU sector is unique in that it comprises both sources and sinks for GHGs. Emissions from the AFOLU sector are estimated to contribute a quarter of the total global greenhouse gas emissions. GHG emissions sources from agriculture include enteric fermentation; manure management; manure deposits on pastures, and soil fertilization. Emissions sources from Forestry and Other Land Use (FOLU) include anthropogenic land use activities such as: management of croplands, forests and grasslands and changes in land use cover (the conversion of one land use to another). South Africa has improved the quantification of AFOLU emissions and the understanding of the dynamic relationship between sinks and sources over the past decade through projects such as the 2010 GHG Inventory, the Mitigation Potential Analysis (MPA), and the National Terrestrial Carbon Sinks Assessment (NTCSA). These projects highlight key mitigation opportunities in South Africa and discuss their potentials. The problem remains that South Africa does not have an emissions baseline for the AFOLU sector against which the mitigation potentials can be measured. The AFOLU sector as a result is often excluded from future emission projections, giving an incomplete picture of South Africa’s mitigation potential. The purpose of this project was to develop a robust GHG emissions baseline for the AFOLU sector which will enable South Africa to project emissions into the future and demonstrate its contribution towards the global goal of reducing emissions

Climate change and urban development in southern Africa : the case of Ekurhuleni Municipality (EMM) in South Africa

In this paper, outcomes from an investigation of plausible climate futures over the next century, and the potential impacts on water services including water resource management and disaster risk reduction, such as flash flooding in Ekurhuleni (EMM), are presented. Four key aspects are examined: (i) the extent to which the frequency of extreme rainfall events may change in South Africa as a result of climate change; (ii) the identification of some of the implications of extreme rainfall events for local government (iii) the identification of some of the challenges communities most at risk of flooding as a result of extreme rainfall events face, finally, (iv) the opportunities for future co-production of design methods and approaches to reduce current and future climate risks in EMM and elsewhere. Climate modelling conducted for this research indicates that it is plausible for an increase in the number of extreme rainfall events to occur over central and eastern South Africa over the next century. Over EMM, for example, an increase in extreme rainfall events is likely to be accompanied by flash flooding and a range of deleterious impacts, if planning and maintenance of the water services infrastructure is not improved – a result that is likely to be valid for all large metropolitan municipalities in the country. The paper provides some lessons learnt when trying to include a climate risk reduction approach into the planning of urban development.The Water Research Commissionhttp://www.wrc.org.zaam201

South African Highveld concentrations of outdoor Total Gaseous Mercury

It is well-known that the Highveld is one of the country's poorest air quality regions. This is due to the abundance of anthropogenic activities such as coal-fired power plants, mining, and cement production among others. The formerly mentioned source is regarded globally and has been extensively studied as the leading source of ambient mercury. Mercury is recurrently oxidized and reduced between its environmental forms. Methyl-mercury poses adverse effects on humans if inhaled/consumed in excessive amounts. In this research, the authors conducted a first-ever characterization of total gaseous mercury (TGM) concentrations over the Highveld regio

Integrated assessment of strategies to reduce air pollution in the Vaal Triangle Priority Area, South Africa

South Africa currently faces a serious problem of air pollution in its cities. The approach used to manage air quality has not yet met the desired outcomes. In this study, potential mitigation options for ambient PM2.5 in the Vaal Triangle Airshed Priority Area (VTAPA)—one of the most industrialised regions in South Africa—were explored using the GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) model. Based on projections of economic activities and population, changes in PM2.5 concentrations were quantified, applying different assumptions on application rates of end-of-pipe control technologies for key emission sources of PM2.5 and its precursor gases NOx and SO2. Ambient PM2.5 concentrations were used to estimate the potential human health benefits of emission reductions. Our findings reveal that PM2.5 concentrations for the VTAPA will not reach recommended air quality limits by 2035 under the current legislation. By introducing stringent controls, emissions will be reduced by more than half, and national air quality standards are attained. Trajectories show that implementation costs in the alternative scenario will nearly be twice as high as those for the current policies. Analysis using the GAINS model has demonstrated the value of assessing the multiple dimensions of air pollution through applying an integrated approach to provide evidence-based support for policy decision-making