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Now showing items 1 - 16 of 32

  • Respiratory health effects of diesel particulate matter

    ZORAN D. RISTOVSKI   BRANKA MILJEVIC   NICHOLAS C. SURAWSKI   LIDIA MORAWSKA   KWUN M. FONG   FELICIA GOH and IAN A. YANG  

    Particulate matter (PM) emissions involve a complex mixture of solid and liquid particles suspended in a gas, where it is noted that PM emissions from diesel engines are a major contributor to the ambient air pollution problem. While epidemiological studies have shown a link between increased ambient PM emissions and respiratory morbidity and mortality, studies of this design are not able to identify the PM constituents responsible for driving adverse respiratory health effects. This review explores in detail the physico-chemical properties of diesel PM (DPM) and identifies the constituents of this pollution source that are responsible for the development of respiratory disease. In particular, this review shows that the DPM surface area and adsorbed organic compounds play a significant role in manifesting chemical and cellular processes that if sustained can lead to the development of adverse respiratory health effects. The mechanisms of injury involved included inflammation, innate and acquired immunity, and oxidative stress. Understanding the mechanisms of lung injury from DPM will enhance efforts to protect at-risk individuals from the harmful respiratory effects of air pollutants.
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  • New Directions: Shall we peel an orange?

    Lidia Morawska  

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  • New Directions: Shall we peel an orange?

    Lidia Morawska  

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  • Ambient air particulate matter: A cause of airway and systemic disease

    Lidia Morawska  

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  • Indoor Particles, Combustion Products and Fibres

    Lidia Morawska  

    Pollutants in an indoor environment are a complex mixture of gases, vapours and particles in either the liquid or the solid phase, suspended in the air, settled or adsorbed on or attached to indoor surfaces. The pollutants originate from a multiplicity of indoor and outdoor sources. The pollutant mixture is dynamic, involved in numerous physical and chemical processes and changes its characteristics with time. Its composition and concentration depend on the strengths of indoor sources, the concentration of pollutants outside and the properties of heating-ventilation and air-conditioning systems. The spatial distribution of pollutant concentration within an indoor environment is often inhomogeneous. Particulate matter in an indoor environment includes particles which are airborne as well as those which are settled on indoor surfaces: dust. The particles vary in chemical properties, which depend on the origin of the particles and differ for particles in different size ranges. The particles can, for example, be combustion products, dust or bioaerosols, and can act as carriers of adsorbed chemicals, biocontaminants or condensed gases. Particles are a key component of emissions from all the combustion sources. In particular, a significant indoor combustion product, environmental tobacco smoke is a mixture of particle and gaseous products of smoke exhaled into the air by smokers and is mixed with the smoke resulting from smouldering of a cigarette between puffs. This chapter is focused on particulate matter, its origin, characteristics and behaviour in an indoor environment. In addition, several important classes of indoor pollutants are discussed: those which are entirely or partially composed of particulate matter. These include environmental tobacco smoke and combustion products from other sources, such as wood smoke or vehicle emissions, and also fibres, in particular, asbestos.
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  • Combustion sources of particles. 1. Health relevance and source signatures

    Lidia Morawska   Junfeng (Jim) Zhang  

    Combustion processes result in generation of a large number of particle and gaseous products that create health and environmental risks. Of particular importance are the very small particles that are emitted in large quantities from all the combustion sources, and that have been shown to be potentially more significant in terms of their impact on health than larger particles. To control and mitigate the particles with a view of health and environmental risk reduction, a good understanding is necessary of the relative and absolute contribution from the emission sources to the airborne concentrations. This understanding could only be achieved by developing source signature libraries through direct emission measurements from the sources on one hand, and by measuring particle concentrations in the air, and apportioning them to the specific local and distant sources using the signatures, on the other hand. This paper is a review of particle characteristics that are used as source signatures as well as their general advantages and limitations. The second part of the paper reviews source signatures of the most common combustion pollution sources.
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  • Experimental study of the deposition of combustion aerosols in the human respiratory tract

    Lidia Morawska   Werner Hofmann   Jane Hitchins-Loveday   Cheryl Swanson   Kerrie Mengersen  

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  • New Directions: Particle air pollution down under

    Lidia Morawska  

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  • The modality of particle size distributions of environmental aerosols

    Lidia Morawska   Stephen Thomas   Milan Jamriska   Graham Johnson  

    Knowledge of the distribution of airborne particulate matter into size fractions has become an increasing area of focus when examining the effects of air pollution. While total number and mass concentrations may play an important role in exposure and risk assessment analyses, often an understanding of the particle size distributions provides more information on the type of atmospheric processes resulting in the distributions. The modality of the particle size distribution is one such aspect that has been associated with the aerosol formation mechanisms. The aim of this work is to provide a detailed analysis of the modal characteristics of a large number of particle size spectra collected over a period of three years for a range of ambient aerosol types. Measurements of over 6000 size distributions in the size range 0.016-30 mum were made using a scanning mobility particle sizer and an aerodynamic particle sizer for various ambient aerosols including: traffic influenced, urban, vegetation burning influenced, marine, modified background and suburban. Advanced data analytical procedures were adopted to combine the distributions from the two instruments for the calculation of the volume size distributions to allow clear interpretation of the modal characteristics. It was determined that, while in most cases there is a distinct nuclei mode in the number size distribution, this does not translate to a nuclei mode in the volume size distribution. Furthermore, while many of the number size distributions were different for each aerosol studied, the volume distributions were similar. This finding has serious implications for the setting of mass-based air quality standards.
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  • The relationship between indoor and outdoor airborne particles in the residential environment

    Lidia Morawska   Congrong He   Jane Hitchins   Dale Gilbert   Sandhya Parappukkaran  

    The relationship between indoor and outdoor airborne particles was investigated for 16 residential houses located in a suburban area of Brisbane, Australia. The submicrometer particle numbers were measured using the Scanning Mobility Particle Sizer, the larger particle numbers using the Aerodynamic Particle Sizer and an approximation of PM2.5 was also measured using a DustTrak. The measurements were conducted for normal and minimum ventilation conditions using simultaneous and non-simultaneous measurement methods designed for the purpose of the study. Comparison of the ratios of indoor to outdoor particle concentrations revealed that while temporary values of the ratio vary in a broad range from 0.2 to 2.5 for both lower and higher ventilation conditions, average values of the ratios were very close to one regardless of ventilation conditions and of particle size range. The ratios were in the range from 0.78 to 1.07 for submicrometer particles, from 0.95 to 1.0 for supermicrometer particles and from 1.01 to 1.08 for PM2.5 fraction. Comparison of the time series of indoor to outdoor particle concentrations shows a clear positive relationship existing for many houses under normal ventilation conditions (estimated to be about and above 2h-1), but not under minimum ventilation conditions (estimated to be about and below 1 h-1). These results suggest that for normal ventilation conditions, outdoor particle concentrations could be used to predict instantaneous indoor particle concentrations but not for minimum ventilation, unless air exchange rate is known, thus allowing for estimation of the "delay constant".
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  • Size characteristics and ageing of the environmental tobacco smoke

    Lidia Morawska   Milan Jamriska   Neville D. Bofinger  

    The work presented here is a study of the behaviour of the particulate phase of ETS under controlled laboratory conditions and in real indoor environments with the aim of providing information for assessment of human exposure to ETS. This paper reports investigations of the size distribution of ETS and changes to the distribution with time under a range of environmental conditions. Measurements were performed using two instruments, the Scanning Mobility Particle Sizer and the Aerodynamic Particle Sizer, which enabled the determination of the precise locations of ETS peaks at frequent short time intervals. While total particle concentrations or changes in concentrations are not specific markers of ETS, peaks related to ETS in the spectral distribution of atmospheric particles, for a properly designed experiment, are. The presence and locations of these peaks are characteristic of ETS in indoor environments and are clearly distinguishable from the background particle distribution. It is demonstrated that an initial ETS size distribution in an indoor environment about 10 min after generation by a human smoker has a major peak in the submicron range between 60 and 90 nm. The location of the peak does not depend on the relative humidity, but does depend on the way the cigarette is smoked. An increase in particle size in the range of 20 to 50%, takes place in the first 30 to 60 min after ETS generation and then remains unchanged for the duration of the experiment. A decrease in particle size (shrinkage), was not observed during these experiments. Particle shrinkage has been reported in the literature. Both the SS and the MS smoke reveal bimodal size distribution. In both cases the most significant, in terms of particle numbers, is the submicron peak. Natural ventilation, which is the most common type of ventilation for residences, is often not sufficient for effectively reducing human exposure to ETS. Controlled chamber experiments are useful for investigations of general trends in ETS size distribution and concentration and the results from such experiments, in most cases, correlate well with those from real indoor measurements. There are however, aspects which show certain differences between the two types of experiments. These differences indicate that chamber experiments can not fully simulate indoor measurements, and results from such experiments should be treated with caution when applied to exposure assessment.
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  • Editorial

    Lidia Morawska  

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  • Characteristics of particle number and mass concentrations in residential houses in Brisbane, Australia

    Lidia Morawska   Congrong He   Jane Hitchins   Kerrie Mengersen   Dale Gilbert  

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  • Modality in ambient particle size distributions and its potential as a basis for developing air quality regulation

    Lidia Morawska   Diane U. Keogh   Stephen B. Thomas    Kerrie Mengersen  

    Current ambient air quality standards are mass-based and restricted to PM2.5 and PM10 fractions. The major contribution to both PM2.5 and PM10 fractions is from particles belonging to the coarse mode and generated by mechanical processes. These standards are thus unable to effectively control particle concentrations from combustion sources, such as motor vehicles and power plants, which tend to emit very small particles that are almost entirely respirable and in the submicron range, and dominate the nucleation and accumulation modes, which contribute much less to particle mass concentration.The aim of this work was to examine whether PM1 and PM10 would be a more effective combination of mass standards than PM2.5 (dominant in the nucleation and accumulation modes) and PM10 (dominant in the coarse mode) in controlling combustion-related ambient particles, as well as those originating from mechanical processes. First, a large body of data on particle size distributions in a range of environments in South East Queensland, Australia, was analysed, with an aim of identifying the relation between modality in the distributions and sources of particles belonging to different modes. The analyses included a matrix of the following elements: particle volume and number distributions, type of environment and locations of the modes in the range of PM1, PM2.5 and PM10 fractions. Second, with the same aim, 600 published modal location values relating to number, surface area, volume and mass size distributions for a range of environments worldwide were analysed. The analysis identified a clear and distinct separation between the location of the modes for a substantial number of environments worldwide and particle metrics, which suggests that modality in particle size distributions may be a parameter that has potential to be used in the development of PM1 air quality guidelines and standards. Based on these analyses, implications for choosing different mass standards for airborne particulate matter are discussed in the paper.
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  • Modality in ambient particle size distributions and its potential as a basis for developing air quality regulation

    Lidia Morawska   Diane U. Keogh   Stephen B. Thomas   Kerrie Mengersen  

    Current ambient air quality standards are mass-based and restricted to PM2.5 and PM10 fractions. The major contribution to both PM2.5 and PM10 fractions is from particles belonging to the coarse mode and generated by mechanical processes. These standards are thus unable to effectively control particle concentrations from combustion sources, such as motor vehicles and power plants, which tend to emit very small particles that are almost entirely respirable and in the submicron range, and dominate the nucleation and accumulation modes, which contribute much less to particle mass concentration.The aim of this work was to examine whether PM1 and PM10 would be a more effective combination of mass standards than PM2.5 (dominant in the nucleation and accumulation modes) and PM10 (dominant in the coarse mode) in controlling combustion-related ambient particles, as well as those originating from mechanical processes. First, a large body of data on particle size distributions in a range of environments in South East Queensland, Australia, was analysed, with an aim of identifying the relation between modality in the distributions and sources of particles belonging to different modes. The analyses included a matrix of the following elements: particle volume and number distributions, type of environment and locations of the modes in the range of PM1, PM2.5 and PM10 fractions. Second, with the same aim, 600 published modal location values relating to number, surface area, volume and mass size distributions for a range of environments worldwide were analysed. The analysis identified a clear and distinct separation between the location of the modes for a substantial number of environments worldwide and particle metrics, which suggests that modality in particle size distributions may be a parameter that has potential to be used in the development of PM1 air quality guidelines and standards. Based on these analyses, implications for choosing different mass standards for airborne particulate matter are discussed in the paper.
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  • A study of the horizontal and vertical profile of submicrometer particles in relation to a busy road

    Lidia Morawska   Stephen Thomas   Dale Gilbert   Chris Greenaway   Esther Rijnders  

    Epidemiological studies are consistently reporting an association between fine particulate pollution and ill-health. Motor vehicle emissions are considered to be the main source of fine particles in ambient urban air of cities which are not directly influenced by industrial emissions. The aim of this work was to assess the influence of a major arterial road on concentration levels of airborne fine particles in its vicinity. Measurements of over 500 particle size distributions in the particle size range 16-626 nm, were made using two scanning mobility particle sizers (SMPS). A subsequent comparison of the recorded values from differing locations is discussed, with reference made to topographic and climatic influences. Both horizontal and vertical profile measurements of fine particle number size distributions are described; the combination of the two yielding information as to the relative exposures of occupants of buildings in the vicinity of a major arterial route. With the exception of measurements in close proximity to the freeway (about 15 m), the horizontal profile measurements did not provide any evidence of a statistically significant difference in fine particle number concentration with respect to distance at ground level up to a distance of 200 m within the study area. The vertical profile measurements also revealed no significant correlation between particle concentration and height. However, for buildings in the immediate proximity to the arterial road (about 15 m) concentrations around the building envelope are very high, comparable to those in the immediate vicinity of the road, indicating undiluted concentrations drawn directly from the freeway. This finding has a significant implication for management of indoor air quality in the buildings located in the immediate vicinity of major roads.
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