Modelling risk exposure of BTEX emissions from a diesel refuelling station in Johannesburg, South Africa

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, August 2015.Petrol and diesel fumes are known to be anthropogenic sources of air pollutants that have a negative impact on both environmental and human health. In developing countries, attendants are still employed to pump fuel for customers. In South Africa gas pump attendants refuel vehicles with various octane unleaded petrol, lead replacement petrol (LRP) and diesel on a daily basis. Attendants are particularly at risk to adverse health effects associated with inhalation of hazardous air pollutants (HAPs). Of increasing concern in recent years are the volatile organic compounds (VOCs), with particular reference to the six aromatic hydrocarbons (benzene, toluene, ethyl benzene and three isomeric xylenes), namely the BTEX

Distribution of Total Volatile Organic Compounds at taxi drivers in Tehran

Air pollution is currently the most serious environmental health threat worldwide. Volatile Organic Compounds (VOC) are considered as the main effective factors in causing air pollution. Vehicles are among the major sources which emit these compounds, so it seems that automobiles’ microenvironment is one of the places where people are exposed to high concentration of VOC. Evaluating the exposure amount of Total Volatile Organic Compounds (TVOC) can indeed be used as an indicator to estimate the amount of exposure to every individual VOC. This study was conducted on the concentration of TVOC inside Tehran taxies for a period of one year. For this purpose, a real time instrument equipped with photo-ionization detector (PID) was used. Consequently, the highest and the lowest measured TVOC in taxies equaled 3.33 ppm and 0.72 ppm, respectively. In addition, the arithmetic mean of TVOC concentration was 1.77±0.53 ppm inside the examined taxies. In this study, the parameters like measurement time, climate and vehicle conditions were found to have significant effect on the amount of exposure to TVOC

Investigating the Variation of Benzene and 1,3-Butadiene in the UK during 2000–2020

The concentrations of benzene and 1,3-butadiene in urban, suburban, and rural sites of the U.K. were investigated across 20 years (2000–2020) to assess the impacts of pollution control strategies. Given the known toxicity of these pollutants, it is necessary to investigate national long-term trends across a range of site types. We conclude that whilst legislative intervention has been successful in reducing benzene and 1,3-butadiene pollution from vehicular sources, previously overlooked sources must now be considered as they begin to dominate in contribution to ambient pollution. Benzene concentrations in urban areas were found to be ~5-fold greater than those in rural areas, whilst 1,3-butadiene concentrations were up to ~10-fold greater. The seasonal variation of pollutant concentration exhibited a maximum in the winter and a minimum in the summer with summer: winter ratios of 1:2.5 and 1:1.6 for benzene and 1,3-butadiene, respectively. Across the period investigated (2000–2020), the concentrations of benzene decreased by 85% and 1,3-butadiene concentrations by 91%. A notable difference could be seen between the two decades studied (2000–2010, 2010–2020) with a significantly greater drop evident in the first decade than in the second, proving, whilst previously successful, legislative interventions are no longer sufficiently limiting ambient concentrations of these pollutants. The health impacts of these pollutants are discussed, and cancer impact indices were utilized allowing estimation of cancer impacts across the past 20 years for different site types. Those particularly vulnerable to the adverse health effects of benzene and 1,3-butadiene pollution are discussed

Sources of non-methane volatile organic compounds in Delhi, India

Cities in India consistently feature amongst the most polluted in the world, with air quality problems driven by rapid and poorly regulated economic growth and development. Many sources emit non-methane volatile organic compounds (NMVOCs), which degrade local and regional air quality through the photochemical formation of tropospheric ozone and secondary organic aerosol (SOA). Large uncertainties in the understanding of NMVOC sources specific to India result in poorly constrained regional policy and global chemical transport models. Consequently, the drivers of the consistently observed poor air quality remain poorly understood. This thesis presents measurements of NMVOCs made in Delhi during pre- and post-monsoon seasons in 2018. The sources of NMVOCs were examined, which showed that NMVOC emissions were principally from petrol and diesel related sources. Very high NMVOC concentrations were measured at night during the post-monsoon campaign. These were shown to be emissions from the local area and were enhanced due to stagnant conditions caused by very low planetary boundary layer heights and windspeeds. Solid fuels represent a large energy source to India, with potentially significant impacts to air quality. Consequently, a detailed source study of organic emissions from solid-fuel combustion sources was conducted. Firstly, a new method for collecting intermediate-volatility and semi-volatile organic gases and particles onto solid-phase extraction disks and Teflon filters, followed by solvent extraction with analysis by two-dimensional gas chromatography coupled to time-of-flight mass spectrometry was evaluated. Secondly, an extremely detailed set of emission factors of NMVOCs were measured with a range of online gas-phase techniques. These results were then mapped onto a volatility-basis dataset and the SOA production potential and OH reactivity of different sources compared. Finally, a high-resolution bottom-up emission inventory was developed for India from 1993-2016. This found that burning of cow dung cake had a disproportionately large impact to NMVOCs from residential combustion

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

Quantification of volatile organic compounds in ten cities across three continents

Volatile organic compounds (VOCs) are emitted from both biogenic and anthropogenic sources. Biogenic compounds dominate VOCs emissions worldwide while the anthropogenic VOCs prevail in urban areas. Apart from undesired and direct human health effects, VOCs can affect the physical-chemical behaviour of the atmosphere in several ways. In addition to influencing local, regional and even global photochemistry, some of these compounds have a potential impact on climate (e.g. due to their ability to form aerosol particles). Despite these facts, few studies have focused on urban environments of developing countries where VOCs levels are expected to be high because of rapid industrialization and lenient regulations. People spend up to 80-90% of their time indoors (houses, offices, bars etc.) and a significant amount of time (5%) in traffic while commuting to and from work. However, air quality (e.g. exposure assessment) concerning a diversity of airborne VOCs for those micro-environments are hardly documented, even in the developed world. Given these considerations, quantitative data on VOCs levels in urban environments are of crucial importance in order to (i) enable comparison of pollution levels and exposure, and (ii) estimate their undesired effects (in particular, ozone formation potential and cancer risk assessment). In this thesis, VOCs have been measured in ten cities across five countries (i.e. Belgium, Vietnam, the Philippines, Bangladesh, and Ethiopia) in Europe, Asia, and Africa. All air sampling has been done in an active way using sorbent tubes filled with Tenax TA. The analysis has been excecuted by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) using internal standard calibration. The quantification resulted in a unique dataset of concentration levels of up to 84 VOCs in 450 samples from urban air regions or micro-environments where hardly data on VOCs exist today. This dataset has been used to make a first estimation of ozone formation potential and cancer risk via inhalation

Automotive air pollution : issues and options for developing countries

Air pollution constitutes an ominous threat to human health and welfare. Its adverse effects are pervasive and may be disaggregated at three levels: (a) local, confined to urban and industrial centers; (b) regional, pertaining to transboundary transport of pollutants; and (c) global, related to build up of greenhouse gases. These effects have been observed globally but the characteristics and scale of the air pollution problem in developing countries are not known; nor has the problem been researched and evaluated to the same extent as in industrialized countries. Air pollution, however, can no longer be regarded as a local or a regional issue as it has global repercussions in terms of the greenhouse effect and depletion of the ozone layer. This paper discusses the contribution of motorized land transport to air pollution problems, with special reference to developing countries. It assesses the adverse effects of air pollution from transport sources, primarily motor vehicles, and reviews possible approaches to bring about improvements. The paper identifies key issues and research needs related to land transport and air pollution in developing countriesTransport and Environment,Environmental Economics&Policies,Montreal Protocol,Energy and Environment,Roads&Highways

Indoor Air Quality: From Sampling to Risk Assessment in the Light of New Legislations

This Special Issue aims to make a concrete technical contribution to the solution of the various problems related to indoor air pollution. In 11 papers, international scientists report the last findings in this field from different points of view including topics such as the IAQ legislation, the role of IAQ in schools, hospitals and (micro)environments in general, the performance of an olfactometer system or the impact of an indoor malodor, BTEX measures in a Fire Station, and a chemical characterization of e-cigarette (e-cig) refill liquids (e-liq). It seems appropriate to encourage the development of reference values or specific action values in order to better manage particularly problematic situations in these environments. In the absence of national references to be used for a comparison, it is possible to use those reported in the legislation of other European countries or, by ad hoc working groups or by analogy, to use other standards such as those relating to ambient air