Xenobiotic particle emission formation in fixed-bed domestic coal combustion

Abstract : Combustion of solid fuels have been reportedly associated with several cases of cardiovascular, respiratory and neurological diseases. Furthermore, it is suggested that premature deaths and morbidity cases may be prevented by the use of clean energy technologies than coal and wood burning. In South Africa, despite 87% of households being connected to the grid, over 50% and 75% of households in urban and rural areas continue to depend on wood and coal for major household activities respectively. In 2004 the Department of Minerals and Energy advocated for the use of toplit updraft method (TLUD) as an interim clean coal burning technology. The initiative has been associated with the reduction of visible smoke/particulate matter (~80%) and coal consumption. However, studies suggest that there might be other emissions other than PM at household or regional level from such technologies which may be detrimental to health and environmental performances, which requires further investigations. This present study has investigated the emissions of xenobiotic pollutants emitted from small-scale combustion technology currently in use and advocated to be used in South African low-income settlements. The study focused on emission factors from small-scale coal combustion technologies, influence of coal properties on emissions, particle size distribution at different combustion phases, the physicochemical properties of emitted particles, risk assessment of BTEX emissions, toxicity and cellular uptake of particulate matter from coal combustion. All experiments were carried out in a laboratory environment in order to minimize contribution of other environmental contaminants, which were not intended for the scope of the project. The emission factors of CO2, CO, and NOx ranged from 98–102 g MJ-1, 4.1–6.4 g MJ-1, and 75–195 mg MJ-1, respectively. Particulate matter (PM2.5 and PM10) emissions were in the range 1.3–3.3 g MJ- 1 for the BLUD method, and 0.2–0.7 g MJ-1 for the TLUD method, for both field and lab-designed stoves. When employing the TLUD method, emission factors of PM2.5/PM10 reduced by up to 80% compared to the business as usual BLUD method. The fuel moisture content (from 2.4 wt.% to 8.6 wt.%) led to an 18 and 30% decrease in fire-power when using the TLUD and BLUD methods, respectively. Measured carbon monoxide (CO) emission factors (EF) increased with an increase in moisture content, while carbon dioxide (CO2) EF remained unchanged. The use of A-grade coal resulted in 49% increase in PM emissions compared with D-grade coal at high ventilation rates. Particles from the top-lit updraft (TLUD) showed an ultrafine geometric mean diameter centred at approximately 109 ± 18.4 nm for the ignition phase, 54.9 ± 5.9 nm for the pyrolysis/flaming phase, and 31.1 ± 5.1 nm for the coking phase. In studying the physical properties of smoke particles from coal burning three types of shapes were classified, viz., spherical organic particles with similar characteristics to tarballs (ignition), soot particles (flaming), and mineral particles (char-burning). Elemental composition was determined using ICP-MS and it was found that 55%, 28% and 17% of the selected elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu 63, Zn) were emitted during the char burning, flaming and ignition phase, respectively. However, during ignition most emitted element were K and Si, which may be used as markers for the simultaneous combustion of wood and coal. When using near-field breathing zone concentration of BTEX in a simulated exposure scenario applicable for a typical coal burning South African household, the cancer risk for adult males iii iii and females, was found to be 1.1 -1.2 and 110-120 folds higher than the US EPA designated risk severity indicator [1E-6], respectively. All four TEX compounds recorded the Hazard Quotient [HQ] of less than 1, indicating a low risk of developing related non-carcinogenic health effects. Lastly, smoke particles emitted from the TLUD ignition from a high-ventilated stove were used to determine the cytotoxicity and cellular uptake. Particles from three combustion phases showed mild toxicity on the bronchial epithelial cells at highest concentration of 150 μg/ml while lower concentrations (20 μg/ml, 60 μg/ml 100 μg/ml) did not indicate significant toxicity on the cells. The results of this study have shown that the emissions of health and environment damaging may be significantly reduced by the correct selection of stove to fuel combinations. The PM emissions are directly proportional to the stove type, fuel properties and ignition method. Stoves with higher ventilation rate ignited using fuel with low moisture content and lit with the TLUD ignition method, produces optimum performance on the reduction of PM2.5 and PM10. However, the use of fire ignition method and coal with different moisture content did not show a convincing reduction on the gaseous emissions. Therefore, it remains important when promoting clean coal burning technologies to take cognisance on non-conclusive information of emission performance, particularly on gaseous emissions. It was further, established that particles emitted from domestic coal burning are of small diameter with an average mean of less than 100 nm. This is concerning due to the longer residence time of small particles on air spaces and higher deposition rate in the lower respiratory track of the exposed individual. The emitted particles low to medium temperature produced organic enriched spherical particle with similar characteristics to tarballs. The emissions of BTEX remains a worrying subject given the high probability of cancer under a defined exposure scenario defined under this project. Therefore, it remains important not to rule out the potential harm associated with gaseous emissions when promoting the technology (use of TLUD ignition method).Ph.D. (Energy Studies

Research article Morphology and elemental analysis of freshly emitted particles from packed-bed domestic coal combustion

Abstract: This study was conducted in a laboratory-controlled environment to analyse the physical properties and elemental composition of coal combustion particles in a brazier. Particles were sampled ~1 m above the stove, using a partector. Particles were collected on gold transmission electron microscopy (TEM) grids, and polycarbonate filters for TEM and inductively coupled plasma mass spectrometry (ICP-MS) analysis, respectively. Particles for elemental analysis were collected on a 37 μm polycarbonate filter, and the exhaust was drawn in using a GilAir Plus pump. During sampling, a 2.5 μm cyclone was attached to the sampling cassette to isolate larger particles. Combustion particles emitted during the early stage of combustion were single organic spherical particles with similar characteristics to tarballs. As the combustion progressed, the particle diameter gradually decreased (from 109 nm), and the morphology changed to smaller particles (to 34.3 nm). The particles formed accretion chain structures, showing evidence of agglomeration. Furthermore, a fluffy microstructure, resembling the formation of soot, was formed in the post flaming phase. In the char-burning phase, an irregular structure of semi-spherical particles was formed, showing evidence of mineral particles infused with small carbonaceous particles. Similarly, with the findings of previous studies, the present research also observed organic spherical particles similar to tarballs. Given that during the ignition phase there was a simultaneous burning of wood as kindling and coal, the provenance of these particle emissions can be attributed to both coal and wood

The Extent of Occupational Health Hazard Impact on Workers: Documentary Evidence from National Occupational Disease Statistics and Selected South African Companies’ Voluntary Corporate Social Responsibility Disclosures

This paper explores the potential of Corporate Social Responsibility disclosures in providing alternative information on the extent of occupational health hazard impact on workers, by selected South African companies operating within the manufacturing and utilities sectors amidst an absent national occupational disease surveillance system. An online internet search was used to retrieve publicly available national occupational disease statistics published between 2001 and 2020, and Corporate Social Responsibility reports of selected South African case companies, published between 2015 and 2020. Content analysis was used to analyse the retrieved documents for both descriptive and numeric data. The collection and reporting of occupational disease data in South Africa is inconsistent. Corporate Social Responsibility disclosures related to occupational health metrics vary between companies. Occupational disease incidence was the least reported of the social aspects in Corporate Social Responsibility disclosures, and/or were reported as a single statistic or combined into occupational safety incidence rates in some instances, obfuscating the true extent of the impact caused by occupational health hazards on workers. Furthermore, noise-induced hearing loss remains the most prevalently reported occupational disease, in general. Corporate Social Responsibility reports point to occupational health hazards requiring regulatory intervention, whilst also providing an alternative information source for occupational disease statistics

Occupational Health and Safety Statistics as an Indicator of Worker Physical Health in South African Industry

Operations in general industry, including manufacturing, expose employees to a myriad of occupational health hazards. To prevent exposure, occupational health and safety regulations were enacted, with both employers and workers instituting various risk reduction measures. The analysis of available occupational disease and injury statistics (indicators of worker physical health) can be used to infer the effectiveness of risk reduction measures and regulations in preventing exposure. Thus, using the READ approach, analyses of occupational disease and injury statistics from South African industry, derived from annual reports of the Compensation Fund, were conducted. The publicly available database of occupational disease and injury statistics from the South African general industry is unstructured, and the data are inconsistently reported. This data scarcity, symptomatic of an absence of a functional occupational disease surveillance system, complicates judgement making regarding the effectiveness of implemented risk reduction measures, enacted occupational health and safety regulations and the status of worker physical health from exposure to workplace hazards. The statistics, where available, indicate that workers continue to be exposed to occupational health impacts within general industry, notwithstanding risk reduction measures and enacted regulations. In particular, worker physical health continues to be impacted by occupational injuries and noise-induced hearing loss. This is suggestive of shortcomings and inefficiencies in industry-implemented preventive measures and the regulatory state. A robust national occupational disease surveillance system is a regulatory tool that should detect and direct policy responses to identified occupational health hazards

Occupational Health Hazards: Employer, Employee, and Labour Union Concerns

This review paper examines the extent of employer, worker, and labour union concerns to occupational health hazard exposure, as a function of previously reported and investigated complaints. Consequently, an online literature search was conducted, encompassing publicly available reports resulting from investigations, regulatory inspection, and enforcement activities conducted by relevant government structures from South Africa, the United Kingdom, and the United States. Of the three countries’ government structures, the United States’ exposure investigative activities conducted by the National Institute for Occupational Safety and Health returned literature search results aligned to the study design, in the form of health hazard evaluation reports reposited on its online database. The main initiators of investigated exposure cases were employers, workers, and unions at 86% of the analysed health hazard evaluation reports conducted between 2000 and 2020. In the synthesised literature, concerns to exposure from chemical and physical hazards were substantiated by occupational hygiene measurement outcomes confirming excessive exposures above regulated health and safety standards in general. Recommendations to abate the confirmed excessive exposures were made in all cases, highlighting the scientific value of occupational hygiene measurements as a basis for exposure control, informing risk and hazard perception. Conclusively, all stakeholders at the workplace should have adequate risk perception to trigger abatement measures

Risk Assessment of Benzene, Toluene, Ethyl Benzene, and Xylene Concentrations from the Combustion of Coal in a Controlled Laboratory Environment

A D-grade type coal was burned under simulated domestic practices in a controlled laboratory set-up, in order to characterize the emissions of volatile organic compounds (VOCs); namely, benzene, toluene, ethylbenzene, and xylenes (BTEX). Near-field concentrations were collected in a shack-like structure constructed using corrugated iron, simulating a traditional house found in informal settlements in South Africa (SA). Measurements were carried out using the Synspec Spectras GC955 real-time monitor over a three-hour burn cycle. The 3-h average concentrations (in µg/m3) of benzene, toluene, ethylbenzene, p-xylene, and o-xylene were 919 ± 44, 2051 ± 91, 3838 ±19, 4245 ± 41 and 3576 ± 49, respectively. The cancer risk for adult males and females in a typical SA household exposure scenario was found to be 1.1 and 1.2 respectively, which are 110- and 120-fold higher than the U.S. Environmental Protection Agency (EPA) designated risk severity indicator (1 × 10−6). All four TEX (toluene, ethylbenzene, p-xylene and o-xylene) compounds recorded a Hazard Quotient (HQ) of less than 1, indicating a low risk of developing related non-carcinogenic health effects. The HQ for TEX ranged from 0.001 to 0.05, with toluene concentrations being the lowest, and ethylbenzene the highest. This study has demonstrated that domestic coal burning may be a significant source of BTEX emission exposure

Assessment of occupational health and safety practices at government mortuaries in Gauteng Province : a cross-sectional study

INTRODUCTION : hospital mortuaries are responsible for the receipt and storage of deceased people. This exposes mortuary workers to a variety of health and safety hazards, which include physical, chemical, ergonomics, biological and psychosocial hazards/stressors. The aim of this study was to assess occupational health and safety practices (OHS) among government mortuary workers in Gauteng province. METHODS : a cross-sectional descriptive study design was conducted between the year 2017 and 2018. A convenient sampling technique was used to sample 11 government hospitals in Gauteng Province. A total of 46 employees participated in the study. Data was collected using structured questionnaires and observational checklists. Ethical clearance and permission to conduct the study were obtained prior to the commencement of the study. Data was analyzed using Statistical Package for the Social Science (SPSS) version 25 software. RESULTS : thirty-one (67%) of the respondents did not know the concept of hazard. Observations indicated that 5 out of 11 (45%) facilities were well maintained with only 2 (18%) of the facilities had the participants wearing the required PPE on duty. There was no association between working experience and having a knowledge of the existing hazards. However, there was a high correlation (P<0.05) between training and adherence to safe practices. CONCLUSION : the OHS practices were poor amongst operational employees. The study highlights the significance of developing and implementing Occupational Health and Safety programmes. We recommend that these programmes should focus on occupational health and safety education, training, supervision, medical surveillance and monitoring strategies must be developed and implemented.http://www.panafrican-med-journal.compm2021School of Health Systems and Public Health (SHSPH

Morphology and elemental analysis of freshly emitted particles from packed-bed domestic coal combustion

This study was conducted in a laboratory-controlled environment to analyse the physical properties and elemental composition of coal combustion particles in a brazier. &nbsp;Particles were sampled ~1 m above the stove, using a partector. Particles were collected on gold transmission electron microscopy (TEM) grids, and polycarbonate filters for TEM and inductively coupled plasma mass spectrometry (ICP-MS) analysis, respectively. Particles for elemental analysis were collected on a 37 µm polycarbonate filter, and the exhaust was drawn in using a GilAir Plus pump. During sampling, a 2.5 µm cyclone was attached to the sampling cassette to isolate larger particles. Combustion particles emitted during the early stage of combustion were single organic spherical particles with similar characteristics to tarballs. As the combustion progressed, the particle diameter gradually decreased (from 109 nm), and the morphology changed to smaller particles (to 34.3 nm). The particles formed accretion chain structures, showing evidence of agglomeration. Furthermore, a fluffy microstructure, resembling the formation of soot, was formed in the post flaming phase. In the char-burning phase, an irregular structure of semi-spherical particles was formed, showing evidence of mineral particles infused with small carbonaceous particles. Similarly, with the findings of previous studies, the present research also observed organic spherical particles similar to tarballs. Given that during the ignition phase there was a simultaneous burning of wood as kindling and coal, the provenance of these particle emissions can be attributed to both coal and wood