ORCID Profile
0000-0001-6874-0230
Current Organisation
Queensland University of Technology
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Atmospheric Sciences | Atmospheric Aerosols | Infectious Agents | Environmental Sciences Not Elsewhere Classified | Physical Sciences Not Elsewhere Classified | Engineering Systems Design | Geophysics | Public Health and Health Services | Environmental Engineering Design | Environmental and Occupational Health and Safety | Atmospheric Dynamics | Cloud Physics | Environmental Engineering not elsewhere classified | Environmental Chemistry (incl. Atmospheric Chemistry) | Environmental Monitoring | Geophysics Not Elsewhere Classified | Atmospheric Sciences not elsewhere classified | Atmospheric Sciences Not Elsewhere Classified |
ANZSRC Socio-Economic Objective (SEO)
Disease Distribution and Transmission (incl. Surveillance and Response) | Environmental Health | Ecosystem Adaptation to Climate Change | Atmospheric Processes and Dynamics | Urban and Industrial Air Quality | Atmospheric Composition (incl. Greenhouse Gas Inventory) | Commercial Building Management and Services | Ground Transport not elsewhere classified | Ground transport | Climate change | Atmospheric processes | Air quality | Air Quality not elsewhere classified | Climate and Climate Change not elsewhere classified | Planning | Environmental health | Environmentally Sustainable Transport not elsewhere classified | Health Protection and/or Disaster Response
Related Links
Publications
Environmental contamination and hospital-acquired infection: factors that are easily overlooked
Publisher: Hindawi Limited
Date: 20-11-2014
DOI: 10.1111/INA.12170
Abstract: There is an ongoing debate about the reasons for and factors contributing to healthcare-associated infection (HAI). Different solutions have been proposed over time to control the spread of HAI, with more focus on hand hygiene than on other aspects such as preventing the aerial dissemination of bacteria. Yet, it emerges that there is a need for a more pluralistic approach to infection control one that reflects the complexity of the systems associated with HAI and involves multidisciplinary teams including hospital doctors, infection control nurses, microbiologists, architects, and engineers with expertise in building design and facilities management. This study reviews the knowledge base on the role that environmental contamination plays in the transmission of HAI, with the aim of raising awareness regarding infection control issues that are frequently overlooked. From the discussion presented in the study, it is clear that many unknowns persist regarding aerial dissemination of bacteria, and its control via cleaning and disinfection of the clinical environment. There is a paucity of good-quality epidemiological data, making it difficult for healthcare authorities to develop evidence-based policies. Consequently, there is a strong need for carefully designed studies to determine the impact of environmental contamination on the spread of HAI.
A robust, portable H-TDMA for field use
Publisher: Elsevier BV
Date: 10-2008
Susceptibility of an Airborne Common Cold Virus to Relative Humidity
Publisher: American Chemical Society (ACS)
Date: 17-12-2021
Ultrafine particles from traffic emissions and children’s health (UPTECH) in Brisbane, Queensland (Australia): Study design and implementation
Publisher: MDPI AG
Date: 02-02-2015
Characterization of iodine particles with Volatilization-Humidification Tandem Differential Mobility Analyser (VH-TDMA), Raman and SEM techniques
Publisher: Copernicus GmbH
Date: 23-02-2006
Abstract: Abstract. Particles formed upon photo-oxidation of CH2I2 and particles of I2O5 and HIO3 have been studied using a Volatilisation and Humidification Tandem Differential Mobility Analyser (VH-TDMA) system. Volatilization and hygroscopic behaviour have been investigated as function of temperature (from 25 to 400°C), humidity (RH from 80 to 98%), initial aerosol sizes (from 27 to 100 nm mobility diameter) and in nitrogen or air as the sheath gasses. The volatility behaviour of particles formed upon photo-oxidation of CH2I2 is more similar to that of HIO3 particles in a filtered sheath air than in nitrogen, with the particle shrinkage occurring at 190°C and accompanied by hygroscopic growth. Despite its high solubility, HIO3 was found not to be hygroscopic at room temperature with no significant growth displayed until the thermodenuder temperature reached 200°C or above when the particles have transformed into I2O5. Diiodopentaoxide (I2O5) particles exhibit relatively low hygroscopic growth factors of 1.2–2 in the humidity range investigated. Scanning Electron Microscopy (SEM) of particles formed upon photo-oxidation of CH2I2 shows that their primary elemental components were iodine and oxygen in a stoichiometric ratio of approximately 1:2 with 10% error. Both Raman spectra and SEM show poor crystallinity for all the aerosols produced.
Volatility Characterization of Cooking-Generated Aerosol Particles
Publisher: Informa UK Limited
Date: 10-05-2011
Quantification of the relationship between fuser roller temperature and laser printer emissions
Publisher: Elsevier BV
Date: 06-2010
Viability of Pseudomonas aeruginosa in cough aerosols generated by persons with cystic fibrosis
Publisher: BMJ
Date: 17-04-2014
Composition and Morphology of Particle Emissions from in-use Aircraft during Takeoff and Landing
Publisher: American Chemical Society (ACS)
Date: 09-05-2013
DOI: 10.1021/ES3046058
Abstract: In order to provide realistic data for air pollution inventories and source apportionment at airports, the morphology and composition of ultrafine particles (UFP) in aircraft engine exhaust were measured and characterized. For this purpose, two independent measurement techniques were employed to collect emissions during normal takeoff and landing operations at Brisbane Airport, Australia. PM1 emissions in the airfield were collected on filters and analyzed using the particle-induced X-ray emission (PIXE) technique. Morphological and compositional analyses of in idual ultrafine particles in aircraft plumes were performed on silicon nitride membrane grids using transmission electron microscopy (TEM) combined with energy-dispersive X-ray microanalysis (EDX). TEM results showed that the deposited particles were in the range of 5-100 nm in diameter, had semisolid spherical shapes and were dominant in the nucleation mode (18-20 nm). The EDX analysis showed the main elements in the nucleation particles were C, O, S, and Cl. The PIXE analysis of the airfield s les was generally in agreement with the EDX in detecting S, Cl, K, Fe, and Si in the particles. The results of this study provide important scientific information on the toxicity of aircraft exhaust and their impact on local air quality.
Novel Method for On-Road Emission Factor Measurements Using a Plume Capture Trailer
Publisher: American Chemical Society (ACS)
Date: 08-12-2007
DOI: 10.1021/ES060179Z
Abstract: The method outlined provides for emission factor measurements to be made for unmodified vehicles driving under real world conditions at minimal cost. The method consists of a plume capture trailer towed behind a test vehicle. The trailer collects a s le of the naturally diluted plume in a 200 L conductive bag and this is delivered immediately to a mobile laboratory for subsequent analysis of particulate and gaseous emissions. The method offers low test turnaround times with the potential to complete much larger numbers of emission factor measurements than have been possible using dynamometer testing. S les can be collected at distances up to 3 m from the exhaust pipe allowing investigation of early dilution processes. Particle size distribution measurements, as well as particle number and mass emission factor measurements, based on naturally diluted plumes are presented. A dilution profile relating the plume dilution ratio to distance from the vehicle tail pipe for a diesel passenger vehicle is also presented. Such profiles are an essential input for new mechanistic roadway air quality models.
JEM Spotlight: Environmental monitoring of airborne nanoparticles
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B912589M
Abstract: The aim of this work was to review the existing instrumental methods to monitor airborne nanoparticles in different types of indoor and outdoor environments in order to detect their presence and to characterise their properties. Firstly the terminology and definitions used in this field are discussed, which is followed by a review of the methods to measure particle physical characteristics including number, concentration, size distribution and surface area. An extensive discussion is provided on the direct methods for particle elemental composition measurements, as well as on indirect methods providing information on particle volatility and solubility, and thus in turn on volatile and semivolatile compounds of which the particle is composed. A brief summary of broader considerations related to nanoparticle monitoring in different environments concludes the paper.
Size distribution of particles emitted from grass fires in the Northern Territory, Australia
Publisher: Elsevier BV
Date: 12-2007
Face Masks and Cough Etiquette Reduce the Cough Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis
Publisher: American Thoracic Society
Date: 02-2017
Theoretical analysis of the motion and evaporation of exhaled respiratory droplets of mixed composition
Publisher: Elsevier BV
Date: 2011
Method for measuring the hygroscopic behaviour of lower volatility fractions in an internally mixed aerosol
Publisher: Elsevier BV
Date: 04-2004
Determining the link between hygroscopicity and composition for semi-volatile aerosol species
Publisher: Copernicus GmbH
Date: 24-07-2018
Abstract: Abstract. Internally and externally mixed aerosols present significant challenges in assessing the hygroscopicity of each aerosol component. This study presents a new s ling technique which uses differences in volatility to separate mixtures and directly examine their respective composition and hygroscopic contribution. A shared thermodenuder and unheated bypass line are continuously cycled between an aerosol mass spectrometer and a volatility and hygroscopicity tandem differential mobility analyser, allowing real-time comparative analysis of heated and unheated aerosol properties. Measurements have been taken of both chamber-generated secondary organic aerosol and coastal marine aerosol at Cape Grim, Australia, to investigate system performance under erse conditions. Despite rapidly changing aerosol properties and the need to restrict analysis to a narrow size range, the former experiment separated the hygroscopic influences of ammonium sulfate and two distinct organic components with similar oxygen to carbon ratios but different volatilities. Analysis of the marine aerosol revealed an external mixture of non-sea-salt sulfates and sea spray aerosol, which likely shared similar volatile fractions composed of sulfuric acid and a non-hygroscopic organic component.
An Investigation into the Characteristics and Formation Mechanisms of Particles Originating from the Operation of Laser Printers
Publisher: American Chemical Society (ACS)
Date: 23-01-2009
DOI: 10.1021/ES802193N
Abstract: While current research has demonstrated that the operation of some laser printers results in emission of high concentrations of ultrafine particles, fundamental gaps in knowledge in relation to the emissions still remain. In particular, there have been no answers provided to questions such as the following: (1) What is the composition of the particles? (2) What are their formation mechanisms? (3) Why are some printers high emitters, while others are low? Considering the widespread use of printers and human exposure to these particles, understanding the process of particle formation is of critical importance. This study, using state-of-the-art instrumental methods, has addressed these three points. We present experimental evidence that indicates that intense bursts of particles are associated with temperature fluctuations and suggest that the difference between high and low emitters lies in the speed and sophistication of the temperature control. We have also shown, for the first time, that the particles are volatile and are of secondary nature, being formed in the air from VOC originating from both the paper and hot toner. Some of the toner is initially deposited on the fuser roller, after which the organic compounds evaporate and then form particles, through one of two main reaction pathways: homogeneous nucleation or secondary particle formation involving ozone.
Characteristics of airborne ultrafine and coarse particles during the Australian dust storm of 23 September 2009
Publisher: Elsevier BV
Date: 08-2011
The Mechanism of Breath Aerosol Formation
Publisher: Mary Ann Liebert Inc
Date: 09-2009
Abstract: Aerosol production during normal breathing is often attributed to turbulence in the respiratory tract. That mechanism is not consistent with a high degree of asymmetry between aerosol production during inhalation and exhalation. The objective was to investigate production symmetry during breathing. The aerosol size distribution in exhaled breath was examined for different breathing patterns including normal breathing, varied breath-holding periods, and contrasting inhalation and exhalation rates. The aerosol droplet size distribution measured in the exhaled breath was examined in real time using an aerodynamic particle sizer. The dependence of the particle concentration decay rate on diameter during breath holding was consistent with gravitational settling in the alveolar spaces. Also, deep exhalation resulted in a four- to sixfold increase in concentration, and rapid inhalation produced a further two- to threefold increase in concentration. In contrast, rapid exhalation had little effect on the measured concentration. A positive correlation of the breath aerosol concentration with subject age was observed. The results were consistent with the breath aerosol being produced through fluid film rupture in the respiratory bronchioles in the early stages of inhalation and the resulting aerosol being drawn into the alveoli and held before exhalation. The observed asymmetry of production in the breathing cycle with very little aerosol being produced by exhalation is inconsistent with the widely assumed turbulence-induced aerosolization mechanism.
The use of carbon dioxide as a tracer in the determination of particle number emissions from heavy-duty diesel vehicles
Publisher: Elsevier BV
Date: 11-2005
Application of the VH‐TDMA technique to coastal ambient aerosols
Publisher: American Geophysical Union (AGU)
Date: 08-2004
DOI: 10.1029/2004GL020126
Size characterization of airborne SiO2 nanoparticles with on-line and off-line measurement techniques: an interlaboratory comparison study
Publisher: Springer Science and Business Media LLC
Date: 15-09-2013
Utility of Three Nebulizers in Investigating the Infectivity of Airborne Viruses
Publisher: American Society for Microbiology
Date: 27-07-2021
DOI: 10.1128/AEM.00497-21
Abstract: Viral respiratory tract infections cause millions of lost days of work and physician visits globally, accounting for significant morbidity and mortality. Respiratory droplets and droplet nuclei from infected hosts are the potential carriers of such viruses within indoor environments.
Ultrafine Particles in Indoor Air of a School: Possible Role of Secondary Organic Aerosols
Publisher: American Chemical Society (ACS)
Date: 18-11-2009
DOI: 10.1021/ES902471A
Abstract: The aim of this work was to investigate ultrafine particles (<0.1 microm) in primary school classrooms, in relation to the classroom activities. The investigations were conducted in three classrooms during two measuring c aigns, which together encompassed a period of 60 days. Initial investigations showed that under the normal operating conditions of the school there were many occasions in all three classrooms where indoor particle concentrations increased significantly compared to outdoor levels. By far the highest increases in the classroom resulted from art activities (painting, gluing, and drawing), at times reaching over 1.4 x 10(5) particle cm(-3). The indoor particle concentrations exceeded outdoor concentrations by approximately 1 order of magnitude, with a count median diameter ranging from 20 to 50 nm. Significant increases also occurred during cleaning activities, when detergents were used. GC-MS analysis conducted on 4 s les randomly selected from about 30 different paints and glues, as well as the detergent used in the school, showed that d-limonene was one of the main organic compounds of the detergent, however, it was not detected in the s les of the paints and the glue. Controlled experiments showed that this monoterpene, emitted from the detergent, reacted with O(3) (at outdoor ambient concentrations ranging from 0.06 to 0.08 ppm) and formed secondary organic aerosols. Further investigations to identify other liquids that may be potential sources of the precursors of secondary organic aerosols were outside the scope of this project, however, it is expected that the problem identified by this study could be more widely spread, since most primary schools use liquid materials for art classes, and all schools use detergents for cleaning. Further studies are therefore recommended to better understand this phenomenon and also to minimize exposure of school children to ultrafine particles from these indoor sources.
A Plume Capture Technique for the Remote Characterization of Aircraft Engine Emissions
Publisher: American Chemical Society (ACS)
Date: 20-05-2008
DOI: 10.1021/ES702581M
Abstract: A technique for capturing and analyzing plumes from unmodified aircraft or other combustion sources under real world conditions is described and applied to the task of characterizing plumes from commercial aircraft during the taxiing phase of the Landing/Take-Off (LTO) cycle. The method utilizes a Plume Capture and Analysis System (PCAS) mounted in a four-wheel drive vehicle which is positioned in the airfield 60 to 180 m downwind of aircraft operations. The approach offers low test turnaround times with the ability to complete careful measurements of particle and gaseous emission factors and sequentially scanned particle size distributions without distortion due to plume concentration fluctuations. These measurements can be performed for in idual aircraft movements at five minute intervals. A Plume Capture Device (PCD) collected s les of the naturally diluted plume in a 200 L conductive membrane conforming to a defined shape. S les from over 60 aircraft movements were collected and analyzed in situ for particulate and gaseous concentrations and for particle size distribution using a Scanning Particle Mobility Sizer (SMPS). Emission factors are derived for particle number, NO(x), and PM2.5 for a widely used commercial aircraft type, Boeing 737 airframes with predominantly CFM56 class engines, during taxiing. The practical advantages of the PCAS include the capacity to perform well targeted and controlled emission factor and size distribution measurements using instrumentation with varying response times within an airport facility, in close proximity to aircraft during their normal operations.
An inventory of particle and gaseous emissions from large aircraft thrust engine operations at an airport
Publisher: Elsevier BV
Date: 06-2011
Insights into the growth of newly formed particles in a subtropical urban environment
Publisher: Copernicus GmbH
Date: 07-12-2015
DOI: 10.5194/ACP-15-13475-2015
Abstract: Abstract. The role of different chemical compounds, particularly organics, involved in the new particle formation (NPF) and its consequent growth are not fully understood. Therefore, this study was conducted to investigate the chemical composition of aerosol particles during NPF events in an urban subtropical environment. Aerosol chemical composition was measured along with particle number size distribution (PNSD) and several other air quality parameters at five sites across an urban subtropical environment. An Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (c-ToF-AMS) and a TSI Scanning Mobility Particle Sizer (SMPS) measured aerosol chemical composition (particles above 50 nm in vacuum aerodynamic diameter) and PNSD (particles within 9–414 nm in mobility diameter), respectively. Five NPF events, with growth rates in the range 3.3–4.6 nm, were detected at two of the sites. The NPF events happened on relatively warmer days with lower condensation sink (CS). Temporal percent fractions of organics increased after the particles grew enough to have a significant contribution to particle volume, while the mass fraction of ammonium and sulfate decreased. This uncovered the important role of organics in the growth of newly formed particles. Three organic markers, factors f43, f44 and f57, were calculated and the f44 vs. f43 trends were compared between nucleation and non-nucleation days. K-means cluster analysis was performed on f44 vs. f43 data and it was found that they follow different patterns on nucleation days compared to non-nucleation days, whereby f43 decreased for vehicle-emission-generated particles, while both f44 and f43 decreased for NPF-generated particles. It was found for the first time that vehicle-generated and newly formed particles cluster in different locations on f44 vs. f43 plot, and this finding can be potentially used as a tool for source apportionment of measured particles.
Observation of the suppression of water uptake by marine particles
Publisher: Elsevier BV
Date: 11-2010
New particle formation and growth at a remote, sub-tropical coastal location
Publisher: Copernicus GmbH
Date: 12-10-2009
Abstract: Abstract. A month-long intensive measurement c aign was conducted in March/April 2007 at Agnes Water, a remote coastal site just south of the Great Barrier Reef on the east coast of Australia. Particle and ion size distributions were continuously measured during the c aign. Coastal nucleation events were observed in clean, marine air masses coming from the south-east on 65% of the days. The events usually began at ~10:00 local time and lasted for 1–4 h. They were characterised by the appearance of a nucleation mode with a peak diameter of ~10 nm. The freshly nucleated particles grew within 1–4 h up to sizes of 20–50 nm. The events occurred when solar intensity was high (~1000 W m−2) and RH was low (~60%). Interestingly, the events were not related to tide height. The volatile and hygroscopic properties of freshly nucleated particles (17–22.5 nm), simultaneously measured with a volatility-hygroscopicity-tandem differential mobility analyser (VH-TDMA), were used to infer chemical composition. The majority of the volume of these particles was attributed to internally mixed sulphate and organic components. After ruling out coagulation as a source of significant particle growth, we conclude that the condensation of sulphate and/or organic vapours was most likely responsible for driving particle growth at sizes greater than 10 nm during the nucleation events. Although there was a possibility that the precursor vapours responsible for particle formation and growth had continental sources, on the balance of available data we would suggest that the precursors were most likely of marine/coastal origin. Furthermore, a unique and particularly strong nucleation event was observed during northerly wind. The event began early one morning (08:00) and lasted almost the entire day resulting in the production of a large number of ~80 nm particles (average modal concentration during the event was 3200 cm−3). The Great Barrier Reef was the most likely source of precursor vapours responsible for this event.
Application of bag sampling technique for particle size distribution measurements
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B907891F
Abstract: Bag s ling techniques can be used to temporarily store the aerosol and therefore provide sufficient time to utilize sensitive but slow instrumental techniques for recording detailed particle size distributions. Laboratory based assessment of the method was conducted to examine size dependant deposition loss coefficients for aerosols held in Velostat bags conforming to a horizontal cylindrical geometry. Deposition losses of NaCl particles in the range of 10 nm to 160 nm were analysed in relation to the bag size, storage time, and s ling flow rate. Results of this study suggest that the bag s ling method is most useful for moderately short s ling periods of about 5 minutes.
The modality of particle size distributions of environmental aerosols
Publisher: Elsevier BV
Date: 11-1999
Face Masks Reduce the Release of Pseudomonas aeruginosa Cough Aerosols When Worn for Clinically Relevant Periods.
Publisher: American Thoracic Society
Date: 15-11-2018
Biomass burning influenced particle characteristics in Northern Territory Australia based on airborne measurements
Publisher: Elsevier BV
Date: 04-2010
Deposition of ambient ultrafine particles in the respiratory tract of children: A novel experimental method and its application
Publisher: Elsevier BV
Date: 2020
Hygroscopic behavior of partially volatilized coastal marine aerosols using the volatilization and humidification tandem differential mobility analyzer technique
Publisher: American Geophysical Union (AGU)
Date: 25-10-2005
DOI: 10.1029/2004JD005657
Particle Number Emissions and Source Signatures of an Industrial Facility
Publisher: American Chemical Society (ACS)
Date: 16-12-2005
DOI: 10.1021/ES048337E
Abstract: The work presented was conducted within the scope of a larger study investigating impacts of the Stuart Oil Shale project, a facility operating to the north of the industrial city of Gladstone, Australia. The aims of the investigations were threefold: (a) the identification of the plant signatures in terms of particle size distributions in the submicrometer range (13-830 nm) through stack measurements, (b) exploring the applicability of these signatures in tracing the source contributions at locations of interest, at a distance from the plant, and (c) assessing the contribution of the plant to the total particle number concentration at locations of interest. The stack measurements conducted for three different conditions of plant operation showed that the particle size distributions were bimodal with average modal count median diameters (CMDs) of 24 (SD 4) and 52 (SD 9) nm. The average of all the particle size distributions recorded within the plant sector at a site located 4.5 km from the plant, over the s ling period when the plant was operating, also showed a bimodal distribution. The modal CMDs in this case were 27 and 50 nm, similar to those at the stack. This bimodal size distribution is distinct from the size distribution of the most common ambient anthropogenic emission source, which is vehicle emissions, and can be considered as a signature of this source. The average contribution of the plant (for plant sector winds) was estimated to be (10.0 +/- 3.8) x 10(2) particles cm(-3) and constituted approximately a 50% increase overthe local particle ambient concentration for plant sector winds. This increase in particle number concentration compared to the local background concentration, while high compared to the clean environment concentration, is not significant when compared to concentrations generally encountered in the urban environment of Brisbane.
Particle and bioaerosol characteristics in a paediatric intensive care unit
Publisher: Elsevier BV
Date: 10-2017
Hygroscopic and volatile properties of marine aerosol observed at Cape Grim during the P2P campaign
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/EN07011
Abstract: Environmental context. The marine environment covers 71% of the Earth’s surface, and accounts for most of the planet’s cloud cover. Water droplets in these clouds all form on pre-existing marine aerosol particles. The number, size and composition of these particles determine the cloud droplet size and consequently, the cloud’s light scattering and precipitation behaviour. Marine aerosols, therefore, have a major influence on the planet’s radiation balance and climate. The origin of marine aerosols is still not completely resolved. The newly developed VH-TDMA technique has been applied to marine aerosols that come from the Southern Ocean. The technique enabled new insights into the composition and structure of these aerosols. It has been found that organic matter constitutes 20–40% of these particles, which suppresses their hygroscopic growth. Abstract. Simultaneous measurement of particle hygroscopic and volatile properties was performed using a VH-TDMA on both Aitken and accumulation mode particles. In addition, deliquescence measurements at different thermodenuder temperatures were also performed. The measurements were part of the P2P c aign which took place in February 2006 at the Cape Grim monitoring station in Tasmania, Australia. During baseline conditions, there was often a volatilisation step that occurred below 125°C in the volatility scans, where up to 25% of the volume is lost. Analysis of the changes in growth as this took place indicates that different substances are responsible for this volatilisation on different days – ammonium nitrate, sulfuric acid, or a volatile non-hygroscopic organic. The major volatilisation in all cases occurred in the temperature range ~140–200°C, which is taken to indicate the presence of ammonium sulfate or ammonium bisulfate. A degree of growth suppression is generally evident before this volatilisation, which indicates that a non-hygroscopic material with a similar volatility to ammonium sulfate/bisulfate may be present, which cannot be distinguished in the volatility scans. Organic matter was typically present at around ~20–40% for these particles. When Aitken and accumulation mode particles were measured on the same day, it was found that the organic content of the smaller particles tended to be higher than the larger particles by roughly 20 percentage points.
Ozone-Initiated Particle Formation, Particle Aging, and Precursors in a Laser Printer
Publisher: American Chemical Society (ACS)
Date: 04-01-2012
DOI: 10.1021/ES203066K
Abstract: An increasing number of researchers have hypothesized that ozone may be involved in the particle formation processes that occur during printing, however no studies have investigated this further. In the current study, this hypothesis was tested in a chamber study by adding supplemental ozone to the chamber after a print job without measurable ozone emissions. Subsequent particle number concentration and size distribution measurements showed that new particles were formed minutes after the addition of ozone. The results demonstrated that ozone did react with printer-generated volatile organic compounds (VOCs) to form secondary organic aerosols (SOAs). The hypothesis was further confirmed by the observation of correlations among VOCs, ozone, and particles concentrations during a print job with measurable ozone emissions. The potential particle precursors were identified by a number of furnace tests, which suggested that squalene and styrene were the most likely SOA precursors with respect to ozone. Overall, this study significantly improved scientific understanding of the formation mechanisms of printer-generated particles, and highlighted the possible SOA formation potential of unsaturated nonterpene organic compounds by ozone-initiated reactions in the indoor environment.
Cystic fibrosis pathogens survive for extended periods within cough-generated droplet nuclei.
Publisher: BMJ
Date: 07-04-2018
DOI: 10.1136/THORAXJNL-2018-211567
Abstract: The airborne route is a potential pathway in the person-to-person transmission of bacterial strains among cystic fibrosis (CF) populations. In this cross-sectional study, we investigate the physical properties and survival of common non- Pseudomonas aeruginosa CF pathogens generated during coughing. We conclude that Gram-negative bacteria and Staphylococcus aureus are aerosolised during coughing, can travel up to 4 m and remain viable within droplet nuclei for up to 45 min. These results suggest that airborne person-to-person transmission is plausible for the CF pathogens we measured.
A Novel Method and Its Application to Measuring Pathogen Decay in Bioaerosols from Patients with Respiratory Disease
Publisher: Public Library of Science (PLoS)
Date: 07-07-2016
Humidity-dependent survival of an airborne influenza a virus: Practical implications for controlling airborne viruses
Publisher: American Chemical Society (ACS)
Date: 20-04-2021
Transmission of bacteria in bronchiectasis and chronic obstructive pulmonary disease: Low burden of cough aerosols
Publisher: Wiley
Date: 27-03-2019
DOI: 10.1111/RESP.13544
Abstract: Aerosol transmission of Pseudomonas aeruginosa has been suggested as a possible mode of respiratory infection spread in patients with cystic fibrosis (CF) however, whether this occurs in other suppurative lung diseases is unknown. Therefore, we aimed to determine if (i) patients with bronchiectasis (unrelated to CF) or chronic obstructive pulmonary disease (COPD) can aerosolize P. aeruginosa during coughing and (ii) if genetically indistinguishable (shared) P. aeruginosa strains are present in these disease cohorts. People with bronchiectasis or COPD and P. aeruginosa respiratory infection were recruited for two studies. Aerosol study: Participants (n = 20) underwent cough testing using validated cough rigs to determine the survival of P. aeruginosa aerosols in the air over distance and duration. Genotyping study: P. aeruginosa sputum isolates (n = 95) were genotyped using the iPLEX20SNP platform, with a subset subjected to the enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) assay to ascertain their genetic relatedness. Aerosol study: Overall, 7 of 20 (35%) participants released P. aeruginosa cough aerosols during at least one of the cough aerosol tests. These cough aerosols remained viable for 4 m from the source and for 15 min after coughing. The mean total aerosol count of P. aeruginosa at 2 m was two colony-forming units. Typing study: No shared P. aeruginosa strains were identified. Low viable count of P. aeruginosa cough aerosols and a lack of shared P. aeruginosa strains observed suggest that aerosol transmission of P. aeruginosa is an unlikely mode of respiratory infection spread in patients with bronchiectasis and COPD.
Relation between particle mass and number for submicrometer airborne particles
Publisher: Elsevier BV
Date: 06-1999
In situ measurements of human cough aerosol hygroscopicity
Publisher: The Royal Society
Date: 05-2021
Abstract: The airborne dynamics of respiratory droplets, and the transmission routes of pathogens embedded within them, are governed primarily by the diameter of the particles. These particles are composed of the fluid which lines the respiratory tract, and is primarily mucins and salts, which will interact with the atmosphere and evaporate to reach an equilibrium diameter. Measuring organic volume fraction (OVF) of cough aerosol has proved challenging due to large variability and low material volume produced after coughing. Here, the diametric hygroscopic growth factors (GF) of the cough aerosol produced by healthy participants were measured in situ using a rotating aerosol suspension chamber and a humidification tandem differential mobility analyser. Using hygroscopicity models, it was estimated that the average OVF in the evaporated cough aerosol was 0.88 ± 0.07 and the average GF at 90% relative humidity (RH) was 1.31 ± 0.03. To reach equilibrium in dry air the droplets will reduce in diameter by a factor of approximately 2.8 with an evaporation factor of 0.36 ± 0.05. Hysteresis was observed in cough aerosol at RH = ∼35% and RH = ∼65% for efflorescence and deliquescence, respectively, and may depend on the OVF. The same behaviour and GF were observed in nebulized bovine bronchoalveolar lavage fluid.
Characterization of expiration air jets and droplet size distributions immediately at the mouth opening
Publisher: Elsevier BV
Date: 02-2009
Sources and dynamics of fluorescent particles in hospitals
Publisher: Hindawi Limited
Date: 05-05-2017
DOI: 10.1111/INA.12380
Abstract: Fluorescent particles can be markers of bioaerosols and are therefore relevant to nosocomial infections. To date, little research has focused on fluorescent particles in occupied indoor environments, particularly hospitals. In this study, we aimed to determine the spatial and temporal variation of fluorescent particles in two large hospitals in Brisbane, Australia (one for adults and one for children). We used an Ultraviolet Aerodynamic Particle Sizer (UVAPS) to identify fluorescent particle sources, as well as their contribution to total particle concentrations. We found that the average concentrations of both fluorescent and non-fluorescent particles were higher in the adults' hospital (0.06×10
Particle and Gaseous Emissions from Commercial Aircraft at Each Stage of the Landing and Takeoff Cycle
Publisher: American Chemical Society (ACS)
Date: 15-12-2008
DOI: 10.1021/ES8013985
Abstract: A novel technique was used to measure emission factors for commonly used commercial aircraft including a range of Boeing and Airbus airframes under real world conditions. Engine exhaust emission factors for particles in terms of particle number and mass (PM2.5), along with those for CO2 and NOx, were measured for over 280 in idual aircraft during the various modes of landing/takeoff (LTO) cycle. Results from this study show that particle number, and NOx emission factors are dependent on aircraft engine thrust level. Minimum and maximum emissions factors for particle number, PM2.5, and NOx emissions were found to be in the range of 4.16 x 10(15)-5.42 x 10(16) kg(-1), 0.03-0.72 g.kg(-1), and 3.25-37.94 g.kg(-1), respectively, for all measured airframes and LTO cycle modes. Number size distributions of emitted particles for the naturally diluted aircraft plumes in each mode of LTO cycle showed that particles were predominantly in the range of 4-100 nm in diameter in all cases. In general, size distributions exhibit similar modality during all phases of the LTO cycle. A very distinct nucleation mode was observed in all particle size distributions, except for taxiing and landing of A320 aircraft. Accumulation modes were also observed in all particle size distributions. Analysis of aircraft engine emissions during LTO cycle showed that aircraft thrust level is considerably higher during taxiing than idling suggesting that International Civil Aviation Organization (ICAO) standards need to be modified as the thrust levels for taxi and idle are considered to be the same (7% of total thrust) (Environmental Protection, Annex 16, Vol. II, Aircraft Engine Emissions, 2nd ed. ICAO--International Civil Aviation Organization: Montreal, 1993).
A Comparative Investigation of Ultrafine Particle Number and Mass Emissions from a Fleet of On-Road Diesel and CNG Buses
Publisher: American Chemical Society (ACS)
Date: 22-07-2008
DOI: 10.1021/ES800394X
Abstract: Particle number, particle mass, and CO2 concentrations were measured on the curb of a busy urban busway used entirely by a mix of diesel and CNG operated buses. With the passage of each bus, the ratio of particle number concentration and particle mass concentration to CO2 concentration in the diluted exhaust plume were used as measures of the particle number and mass emission factors, respectively. With all buses accelerating pastthe monitoring point, the results showed that the median particle mass emission from CNG buses was less than 9% of that from diesel buses. However, the median particle number emission from CNG buses was 6 times higher than the diesel buses, and the particles from the CNG buses were mainly in the nanoparticle size range. Using a thermodenuder to remove the volatile material from the s led emissions showed that the majority of particles from the CNG buses, but not from the diesel buses, were volatile. Approximately, 82% of the particles from the CNG buses and 38% from the diesel buses were removed by heating the emissions to 300 degrees C.
Exposure to ambient air pollution and risk of childhood cancers: A population-based study in Tehran, Iran
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.SCITOTENV.2018.07.219
Abstract: The relationship between air pollution and childhood cancer is inconclusive. We investigated the associations between exposure to ambient air pollution and childhood cancers in Tehran, Iran. This project included children between 1 and 15 years-of-age with a cancer diagnosis by the Center for the Control of Non Communicable Disease (n = 161) during 2007 to 2009. Controls were selected randomly within the city using a Geographic Information System (GIS) (n = 761). The cases were geocoded based on exact home addresses. Air pollution exposure of cases and random controls were estimated by a previously developed Land Use Regression (LUR) model for the 2010 calendar year. The annual mean concentrations of Particulate Matter ≤ 10 μm (PM
Emissions from a vehicle fitted to operate on either petrol or compressed natural gas
Publisher: Elsevier BV
Date: 05-05-2004
Size distribution and sites of origin of droplets expelled from the human respiratory tract during expiratory activities
Publisher: Elsevier BV
Date: 03-2009
Precursors to Particles (P2P) at Cape Grim 2006: campaign overview
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/EN07041
Abstract: Environmental context. Understanding the role of clouds in assessing the impact of climate change is a challenging issue. It is thought that plankton and seaweed contribute to the formation of clouds by emitting gases that lead to the particle production necessary for cloud formation. Macroalgae (kelp) at Mace Head, Ireland, produce large quantities of iodine when exposed to sunlight at low tide and this iodine results in the rapid production of particles. Cape Grim, Tasmania, also has large colonies of kelp and the role of Bull Kelp (Durvillaea potatorum) in particle production was assessed. Abstract. Iodine emissions from coastal macroalgae have been found to be important initiators for nucleation events at Mace Head, Ireland. The source of this iodine is the large beds of the brown kelp Laminaria digitata, which are significantly exposed at low tide. On the coast around Cape Grim, Tasmania, there are beds of the brown kelp Durvillaea potatrum. The Precursors to Particles 2006 (P2P 2006) c aign at the Cape Grim Baseline Air Pollution Station in late summer (February) 2006 focused on the role of this local kelp in providing precursor gases to particle formation. Durvillaea potatorum does not produce iodated precursor gases at the levels observed at Mace Head. IO was measured at 0.5 ± 0.3 ppt, while OIO was below detection limits (9 ppt). The dominant atmospheric iodated species was methyl iodide and the average concentration measured at the Cape Grim Station was 1.5 ± 0.3 pptv in baseline conditions, but showed significant variation in discrete s les collected immediately above the ocean surface. Nucleation events were not detected at the Cape Grim Station, except for one period where the plume of a local bushfire interacted with air of marine origin. The passage of four fronts did not result in nucleation bursts and measurements on the beach 94 m below the Cape Grim Station suggested that Durvillaea potatorum was only a weak source of new particles.
Nanomechanics and Morphology of Simulated Respiratory Particles
Publisher: American Chemical Society (ACS)
Date: 19-07-2022
Abstract: The impact of respiratory particle composition on the equilibrium morphology and phase is not well understood. Furthermore, the effects of these different phases and morphologies on the viability of viruses embedded within these particles are equally unknown. Physiologically relevant respiratory fluid analogues were constructed, and their hygroscopic behavior was measured using an ensemble technique. A relationship between hygroscopicity and protein concentration was determined, providing additional validation to the high protein content of respiratory aerosol measured in prior works (>90%). It was found that the salt component of the respiratory particles could crystallize as a single crystal, multiple crystals, or would not crystallize at all. It was found that dried protein particles at indoor-relevant climatic conditions could exist separately in a glassy (∼77% of particles) or viscoelastic state (∼23% of particles). The phase state and morphology of respiratory particles may influence the viability of embedded pathogens. We recommend that pathogen research aiming to mimic the native composition of respiratory fluid should use a protein concentration of at least 90% by solute volume to improve the representativity of the pathogen's microenvironment.
Long term laser frequency control for applications in atomic physics
Publisher: IOP Publishing
Date: 26-10-2000
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