Showing papers by "Lidia Morawska published in 2007"

Particle emission characteristics of office printers.

Abstract: In modern society, printers are widely used in the office environment This study investigated particle number and PM25 emissions from printers using the TSI SMPS, TSI CPC 3022 and 3025A TSI P-Trak and DustTrak The monitoring of particle characteristics in a large open plan office, conducted continuously for over 48 hours, showed that particles generated by printers can significantly (p = 001) affect the submicrometer particle number concentration levels in the office An investigation of the submicrometer particle emissions produced by each of the 62 printers used in the office building was also conducted In terms of emission levels, the printers were divided into four classes of non-emitters, low, medium and high emitters, based on the particle concentrations in the immediate vicinity of the printers, after a short printing job It was found that about 60% of the investigated printers did not emit submicrometer particles and of the 40% that did emit particles, 27% were high particle emitters Particle emission characteristics from three different laser printers were also studied in an experimental chamber, which showed that particle emission rates are printer type–specific and are affected by toner coverage and cartridge age The average particle number emission rates from a printer in the class “low emitter‿ were 004×109 particle min-1 (new cartridge with 5% toner coverage); 421×109 particle min-1 and 954×109 particle min-1 for a “medium emitter‿ (old cartridge with 5% and 50% toner coverage, respectively); and 411×109 particle min-1 (old cartridge, 5% toner coverage), 928×109 particle min-1 (old cartridge, 50% toner coverage), 763×109 particle min-1 (new cartridge, 5% toner coverage) and 159×109 particle min-1 (new cartridge, 50% toner coverage) for a “high emitter‿ Particle size distributions indicated that the higher emitters tended to generate more ultrafine particles (< 01 µm) than the lower emitters whilst the trend in PM25 emissions was different, with the “low emitter‿ in having a PM25 emission rate of (029 ±007 µg min-1) and the “high emitter‿ showing nearly zero mass emissions While a more comprehensive study is still required to provide a better database of printer emission rates, as well as their chemical characteristics, the results from this study imply that submicrometer particle concentration levels in an office can be reduced by a proper choice of the printers

Novel Method for On-Road Emission Factor Measurements Using a Plume Capture Trailer

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 sample 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. Samples 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 p...

Polycyclic aromatic hydrocarbons in house dust samples: Source identification and apportionment

Abstract: House dust is a heterogeneous matrix, consisting of a variety of inorganic, organic and biological materials. Once pollutants are adsorbed onto house dust particles, they either do not degrade at all or degrade at rates that are relatively slower than their ambient counterparts. Thus house dusts are useful reservoirs for chronic exposure to indoor pollutants. In this study, house dust samples from suburban houses in Brisbane, Australia were collected in summer 2004 and winter 2005. Given the growing need to understand the potential risks of indoor pollutants and to develop appropriate control strategies, the objective of the study was to use receptor-oriented models to estimate the number of sources, their compositions and the contribution of each source to the samples. Thus the polycyclic aromatic hydrocarbon (PAH) composition data were analyzed with advanced factor analysis models. Four factors were required to reproduce the summer data well and each factor had distinctive compositions that suggested that natural gas utilities, cooking, vehicle emissions and miscellaneous combustion processes are the main sources of PAHs in the samples. The implications of the results and of the observed correlation between the building characteristics and the PAH profiles on the quality of these indoor microenvironments and the development of control strategies are discussed.

Rapid Identification of High Particle Number Emitting On-Road Vehicles and Its Application to a Large Fleet of Diesel Buses

Abstract: Pollutant concentrations measured in the exhaust plume of a vehicle may be related to the pollutant emission factor using the CO2 concentration as a measure of the dilution factor. We have used this method for the rapid identification of high particle number (PN) emitting on-road vehicles. The method was validated for PN using a medium-duty vehicle and successfully applied to measurements of PN emissions from a large fleet of on-road diesel buses. The ratio of PN concentration to CO2 concentration, Z, in the exhaust plume was estimated for individual buses. On the average, a bus emitted about 1.5 × 109 particles per mg of CO2 emitted. A histogram of the number of buses as a function of Z showed, for the first time, that the PN emissions from diesel buses followed a gamma distribution, with most of the values within a narrow range and a few buses exhibiting relatively large values. It was estimated that roughly 10% and 50% of the PN emissions came from just 2% and 25% of the buses, respectively. A regressi...

The rapid identification of high particle number emitting on-road vehicles and its application to a large fleet of diesel buses

Abstract: Pollutant concentrations measured in the exhaust plume of a vehicle may be related to the pollutant emission factor using the CO2 concentration as a measure of the dilution factor. We have used this method for the rapid identification of high particle number (PN) emitting on-road vehicles. The method was validated for PN using a medium-duty vehicle and successfully applied to measurements of PN emissions from a large fleet of on-road diesel buses. The ratio of PN concentration to CO2 concentration, Z, in the exhaust plume was estimated for individual buses. On the average, a bus emitted about 1.5 x 109 particles per mg of CO2 emitted. A histogram of the number of buses as a function of Z showed, for the first time, that the PN emissions from diesel buses followed a gamma distribution, with most of the values within a narrow range and a few buses exhibiting relatively large values. It was estimated that roughly 10% and 50% of the PN emissions came from just 2% and 25% of the buses, respectively. A regression analysis showed that there was a positive correlation between Z and age of buses, with the slope of the best line being significantly different from zero. The mean Z value for the pre-Euro buses was significantly greater than each of the values for the Euro I and II buses.

Diurnal variation of PM10 concentrations and its spatial distribution in the South East Queensland airshed

Abstract: The aim of this work was quantification of the diurnal variation of PM10 concentration and the variation in its spatial distribution in the South East Queensland (SEQ) airshed with a specific focus on vehicle emissions as a contributing factor. The PM10 concentrations recorded at half-hourly intervals at six monitoring stations over a four-year period were used. Concentrations below 30 mug m-3 recorded at wind speeds less than 2.5 ms-1 and during times of clear visibility were selected for the analysis to lower the probability of interference from non-vehicular sources. The concentrations recorded between 2:00 and 5:00 am were considered to be the urban baseline and subtracted from the daytime readings to obtain a mean difference in concentration between daytime and night time. For a four-year period this mean difference in PM10 concentrations estimated for all the monitoring stations varied in the range between 3.8 and 6.9 mug m-3. In addition to the diurnal variation in the depth of the boundary layer (which was not quantified), vehicle emissions were concluded to be the major contributor to this variation. The method used in this study for quantification of the diurnal variation and spatial distribution of PM10 provides useful information on the influence of motor vehicle emissions on air quality, particularly in relation to human exposure. It provides information not directly available using source emission inventories, which yield data on the total emissions to the air, and cannot be directly translated into concentrations in the different areas of the airshed.

State of epidemiological evidence for health impacts of ultrafine particles

Abstract: There has been increasing interest in the effect of ultrafine particles (UFP) on human cardiovascular and respiratory health. The adverse health impacts due to particle exposure are currently attributed to the mass concentration or the chemical composition of particles smaller than 10 μm (PM) or 2.5 μm (PM) in diameter. However, it has been hypothesised that it is actually UFP (< 0.1 urn) measured in terms of number concentration, as opposed to mass concentration, that might be responsible for the observed health effects. This paper presents the results of a critical literature review aimed at analysing the current state of epidemiological evidence for the effects of UFP on human health. In summary, the array of epidemiological studies conducted thus far suggests that UFP exposure is associated with human mortality, and respiratory and cardiovascular morbidity. This holds true despite the considerable gaps in knowledge that remain, and despite the inconsistencies found between some studies, resulting from some deficiencies in the study designs. The limited number of epidemiological studies conducted thus far indicates that there are comparable health effects of fine and ultrafine particles, which appear to be independent of each other. Fine particles show more immediate effects whilst ultrafine particles show more delayed effects on mortality. However, at present the database is too limited (in terms of both number of studies and number of subjects) and geographically restricted, to allow clear conclusions on the mode of action and/or generalisation to other settings. Consequently, it is recommended that further, better-designed studies be initiated to improve the understanding of health impacts of UFP.

A novel method for on road emission factor measurements using a plume capture trailer

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 sample of the naturally diluted plume in a 200 liter 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. Samples can be collected at distances up to three meters 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.

Air Quality and Its Impact on Health: Focus on Particulate Matter

Abstract: Inadequate air quality and the inhalation of airborne pollutants pose many risks to human health and wellbeing, and are listed among the top environmental risks worldwide. The importance of outdoor air quality was recognised in the 1950s and indoor air quality emerged as an issue some time later and was soon recognised as having an equal, if not greater importance than outdoor air quality. Identification of ambient air pollution as a health hazard was followed by steps, undertaken by a broad range of national and international professional and government organisations, aimed at reduction or elimination of the hazard. However, the process of achieving better air quality is still in progress. The last 10 years or so have seen an unprecedented increase in the interest in, and attention to, airborne particles, with a special focus on their finer size fractions, including ultrafine (< 0.1 m) and their subset, nano particles (< 0.05 m). This paper discusses the current status of scientific knowledge on the links between air quality and health, with a particular focus on airborne particulate matter, and the directions taken by national and international bodies to improve air quality.

State of Epidemiological Evidence for the Health Impacts of Ultrafine Particles

Abstract: There has been increasing interest in the effect of ultrafine particles (UFP) on human cardiovascular and respiratory health. The adverse health impacts due to particle exposure are currently attributed to the mass concentration or the chemical composition of particles smaller than 10 μm (PM10) or 2.5 μm (PM2.5) in diameter. However, it has been hypothesised that it is actually UFP (< 0.1 μm) measured in terms of number concentration, as opposed to mass concentration, that might be responsible for the observed health effects. This paper presents the results of a critical literature review aimed at analysing the current state of epidemiological evidence for the effects of UFP on human health. In summary, the array of epidemiological studies conducted thus far suggests that UFP exposure is associated with human mortality, and respiratory and cardiovascular morbidity. This holds true despite the considerable gaps in knowledge that remain, and despite the inconsistencies found between some studies, resulting from some deficiencies in the study designs. The limited number of epidemiological studies conducted thus far indicates that there are comparable health effects of fine and ultrafine particles, which appear to be independent of each other. Fine particles show more immediate effects whilst ultrafine particles show more delayed effects on mortality. However, at present the database is too limited (in terms of both number of studies and number of subjects) and geographically restricted, to allow clear conclusions on the mode of action and/or generalisation to other settings. Consequently, it is recommended that further, better-designed studies be initiated to improve the understanding of health impacts of UFP.

Hygroscopic and Volatile Properties of Ultrafine Particles in the Eucalypt Forests: Comparison with Chamber Experiments and the Role of Sulphates in New Particle Formation

Abstract: Simultaneous measurements of the volatile and hygroscopic properties of ultrafine particles were conducted in a Eucalypt forest in Tumbarumba, South-East Australia, in November 2006 These measurements were part of an intensive field campaign EUCAP 2006 (Eucalypt Forest Aerosols and Precursors) The particles exhibited a 2 step volatilisation with the first component starting to evaporate at temperatures above 50 degrees Celsius With the onset of evaporation of the first component the hygroscopic growth factor increased This indicated that the particle was composed of a less volatile, but more hygroscopic core, which was coated with a more volatile, but less hygroscopic, coating The fraction of the more hygroscopic component was proportional to the measured maximum SO2 concentration indicating the role of gaseous H2SO4 in new particle formation As the volatilisation temperature of the second more hygroscopic component was above that for H2SO4 it is likely that this component is partially or fully neutralised H2SO4 Comparison with pinene smog chamber experiments shows an excellent agreement with the first step volatilisation indicating its origin in the photooxidation of a monoterpene precursor

Diurnal variation of PM10 concentrations and its spatial distribution in the South East Queensland airshed

Abstract: The aim of this work was quantification of the diurnal variation of PM10 concentrations and the variation in its spatial distribution in the South East Queensland (SEQ) airshed with a specific focus on vehicle emissions as a contributing factor. The PM10 levels recorded at half-hourly intervals at six monitoring stations over a four-year period were used. Levels below 30 g m-3 recorded at wind speeds less than 2.5 ms-1 and during times of clear visibility were selected for the analysis to lower the probability of interference from non-vehicular sources. The levels recorded between 2:00 and 5:00 am were considered to be the urban baseline and subtracted from the daytime readings to obtain a mean difference in concentration between daytime and night time. For a four-year period this mean difference in PM10 levels estimated for all the monitoring stations varied in the range between 3.8 and 6.9 g m-3. In addition to the diurnal variation in the depth of the boundary layer (which was not quantified), vehicle emissions were concluded to be the major contributor to this variation. The method used in this study for quantification of the diurnal variation and spatial distribution of PM10 provides useful information on the influence of motor vehicle emissions on air quality, particularly in relation to human exposure. It provides information not directly available using source emission inventories, which yield data on the total emissions to the air, and cannot be directly translated into concentrations in the different areas of the airshed.

Atmospheric Aerosol and Ion Characteristics during EUCAP (Eucalypt Forest Aerosols and Precursors)

Abstract: We measured the characteristics and dynamics of atmospheric ions, aerosol particles, and their precursors in an intensive field campaign in a Eucalypt forest in Tumbarumba, South-East Australia, in November 2006. The measured size range of ions was 0.34 to 40 nm and that of aerosol particles approximately 10 to 168 nm, and for observing their size distributions we used an Air Ion Spectrometer (AIS) and a Scanning Mobility Particle Sizer (SMPS). We also measured the hygroscopic and chemical properties of the particles with a Volatility-Humidity Tandem Differential Mobility Analyser (VH-TDMA). The total concentration of ultrafine aerosol particles was measured with a Condensational Particle Counter (CPC). Furthermore, we measured ambient concentrations of volatile organic compounds (VOC), SOx, NOx/NOy, and O3. Finally, we modelled the 96-h back trajectories of air masses arriving at the site and observed that the arrival directions varied greatly and included trajectories that travelled only over land as well as ones that travelled most of the time over the ocean. On the most polluted day, the air masses arrived approximately from the direction of greater Sydney / Newcastle coal mine area. The total concentration of ultrafine aerosol particles was approximately 3500 cm-3, and daytime aerosol formation took place on 64% of days with acceptable data. The dominant VOCs were isoprene, eucalyptol, a- and b-pinene, camphene, and limonene. The measured hygroscopic growth factors (Gh) at RH of 90% varied from 1.1 to 1.5. The smallest Gh were observed for aged accumulation mode particles in early mornings, and the largest Gh occurred for the freshly nucleated particles on Nov 10, the day with the highest concentration of SO2.

A simple and inexpensive dilution system for the TSI 3007 condensation particle counter

Abstract: The aim of this study was to develop a dilution system which would permit the TSI 3007 Condensation Particle Counter (CPC) to operate within its maximum detectable concentration threshold, even when sampling extremely high submicron particle concentrations. The intention of this was to provide a better alternative to coincidence correction factors, which have several limitations; the most significant of which being that they are only applicable to a comparatively low concentration and also that the components of the unit are exposed to concentrations beyond their operating specifications. To achieve the aim, a bifurcation based system was developed and tested repeatedly at concentrations of unleaded petrol combustion particles up to ~8.5×106 p/cc. The benchmark particle concentration was measured by a TSI 3022A CPC. The results of the tests showed that the nominal dilution ratio based on flow partitioning was applicable up to ~3.5×105 p/cc, after which particle losses to a capillary tube caused a large increase in apparent dilution. These losses were consistent throughout all tests and allowed the unit to remain below the maximum detection threshold, even under the extreme challenge concentrations encountered. This work represents a useful extension of the operating range of the TSI 3007, without significantly compromising either the quality of data collected or the internal components of the unit.