Showing papers by "Lidia Morawska published in 2011"

Observation of new particle formation in subtropical urban environment

Abstract: . The aim of this study was to characterise the new particle formation events in a subtropical urban environment in the Southern Hemisphere. The study measured the number concentration of particles and its size distribution in Brisbane, Australia during 2009. The variation of particle number concentration and nucleation burst events were characterised as well as the particle growth rate which was first reported in urban environment of Australia. The annual average NUFP, NAitken and NNuc were 9.3×103, 3.7×103 and 5.6×103 cm−3, respectively. Weak seasonal variation in number concentration was observed. Local traffic exhaust emissions were a major contributor of the pollution (NUFP) observed in morning which was dominated by the Aitken mode particles, while particles formed by secondary formation processes contributed to the particle number concentration during afternoon. Overall, 65 nucleation burst events were identified during the study period. Nucleation burst events were classified into two groups, with and without particles growth after the burst of nucleation mode particles observed. The average particle growth rate of the nucleation events was 4.6 nm h−1 (ranged from 1.79–7.78 nm h−1). Case studies of the nucleation burst events were characterised including (i) the nucleation burst with particle growth which is associated with the particle precursor emitted from local traffic exhaust emission, (ii) the nucleation burst without particle growth which is due to the transport of industrial emissions from the coast to Brisbane city or other possible sources with unfavourable conditions which suppressed particle growth and (iii) interplay between the above two cases which demonstrated the impact of the vehicle and industrial emissions on the variation of particle number concentration and its size distribution during the same day.

Volatility Characterization of Cooking-Generated Aerosol Particles

Abstract: Cooking-generated aerosol characterization is crucial for providing an accurate evaluation of human exposure to particle concentrations. In addition, when evaluating the dimensional properties of aerosols emitted from cooking activities, one key aspect to be investigated is the composition of the particles emitted. To this end, an evaluation of the volatility of cooking-generated aerosol particles was performed in this study. Total concentration and size distribution measurements were carried out using a thermal conditioning device, along with a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS), in order to evaluate the amount of volatile material emitted by different cooking activities (frying and grilling), as well as those involving different kinds of food (fatty and vegetable foods). The results showed a shift in the dominant size distribution mode toward smaller diameters with higher aerosol conditioning temperatures. The corresponding total number concentrations were ro...

An inventory of particle and gaseous emissions from large aircraft thrust engine operations at an airport

Abstract: Published particle number emission factors for aircraft operations remain very sparse and so far such emissions have not been included in the International Civil Aviation Organization (ICAO) databases. This work addresses this gap in knowledge by utilizing recent progress in the quantification of aircraft particle emissions. Annual emissions of particle number (PN), particle mass (PM2.5) and NOx throughout the aircraft landing and takeoff (LTO) cycles and ground running procedures (GRP) are presented for aircraft using Brisbane Airport BNE (domestic and international). The aircraft are grouped according to an airframe based classification system. The resulting data are then used to develop an emissions inventory for large aircraft thrust engine operations on the ground, during LTO cycles and GRP, at the Airport. Annual PN, PM2.5 and NOx emissions from large aircraft operations during LTO cycles and GRP at BNE were 1.98 × 1024 yr−1, 1.35 × 104 kg yr−1 and 8.13 × 105 kg yr−1, respectively. Results showed that LTO cycles contribute more than 97% of these annual emissions at BNE in comparison to GRP related emissions. Analysis of the LTO cycle contribution to the daily emissions showed that the contribution of the climbout mode is considerably higher than for other individual LTO operational modes. Emissions during aircraft departures were significantly higher than those during arrival operations, due to the higher aircraft engine emission rates during takeoff and climbout.

Exposure to particles from laser printers operating within office workplaces.

Abstract: While recent research has provided valuable information as to the composition of laser printer particles, their formation mechanisms, and explained why some printers are emitters while others are low emitters, questions relating to the potential exposure of office workers remained unanswered. In particular, (i) what impact does the operation of laser printers have on the background particle number concentration (PNC) of an office environment over the duration of a typical working day? (ii) What is the airborne particle exposure to office workers in the vicinity of laser printers? (iii) What influence does the office ventilation have upon the transport and concentration of particles? (iv) Is there a need to control the generation of, and/or transport of particles arising from the operation of laser printers within an office environment? (v) What instrumentation and methodology is relevant for characterizing such particles within an office location? We present experimental evidence on printer temporal and spatial PNC during the operation of 107 laser printers within open plan offices of five buildings. The 8 h time-weighted average printer particle exposure is significantly less than the 8 h time-weighted local background particle exposure, but that peak printer particle exposure can be greater than 2 orders of magnitude higher than local background particle exposure. The particle size range is predominantly ultrafine (<100 nm diameter). In addition we have established that office workers are constantly exposed to nonprinter derived particle concentrations, with up to an order of magnitude difference in such exposure among offices, and propose that such exposure be controlled along with exposure to printer derived particles. We also propose, for the first time, that peak particle reference values be calculated for each office area analogous to the criteria used in Australia and elsewhere for evaluating exposure excursion above occupational hazardous chemical exposure standards. A universal peak particle reference value of 2.0 × 10(4) particles cm(-3) has been proposed.

Exposure to particles from laser printers operating within office workplaces

Abstract: While recent research has provided valuable information as to the composition of laser printer particles, their formation mechanisms, and explained why some printers are emitters whilst others are low emitters, fundamental questions relating to the potential exposure of office workers remained unanswered. In particular, (i) what impact does the operation of laser printers have on the background particle number concentration (PNC) of an office environment over the duration of a typical working day?; (ii) what is the airborne particle exposure to office workers in the vicinity of laser printers; (iii) what influence does the office ventilation have upon the transport and concentration of particles?; (iv) is there a need to control the generation of, and/or transport of particles arising from the operation of laser printers within an office environment?; (v) what instrumentation and methodology is relevant for characterising such particles within an office location? We present experimental evidence on printer temporal and spatial PNC during the operation of 107 laser printers within open plan offices of five buildings. We show for the first time that the eight-hour time-weighted average printer particle exposure is significantly less than the eight-hour time-weighted local background particle exposure, but that peak printer particle exposure can be greater than two orders of magnitude higher than local background particle exposure. The particle size range is predominantly ultrafine (< 100nm diameter). In addition we have established that office workers are constantly exposed to non-printer derived particle concentrations, with up to an order of magnitude difference in such exposure amongst offices, and propose that such exposure be controlled along with exposure to printer derived particles. We also propose, for the first time, that peak particle reference values be calculated for each office area analogous to the criteria used in Australia and elsewhere for evaluating exposure excursion above occupational hazardous chemical exposure standards. A universal peak particle reference value of 2.0 x 104 particles cm-3 has been proposed.

Using the Generalised Additive Model to model the particle number count of ultrafine particles

Abstract: Abstract In this paper, we compare the Generalised Linear Model (GLM) and Generalised Additive Model (GAM) for modelling the particle number concentration (PNC) of outdoor, airborne ultrafine particles in Helsinki, Finland. We examine temporal trends in PNC and examine the relationship between PNC and rainfall, wind speed and direction, humidity, temperature and solar insolation. Model choice is via the Akaike Information Criterion (AIC). We have shown that the Generalised Additive Model provides a better fit than the equivalent Generalised Linear Model (ELM) when fitting models with the same covariates with equivalent degrees of freedom (AIC and BIC for the GAM are 10266.52 and 10793.04, AIC and BIC for the ELM are 10297.19 and 10885.97, both have an R2 value of 0.836). We also present results that show that modelling both temporal trends and the effect of rainfall, wind speed and direction, humidity, temperature and solar insolation yields a better fitting model, according to the AIC, than either temporal trends or meteorological conditions by themselves. The model is applicable to any longitudinal monitoring-type measurement campaign where long time series are recorded. Use of this technique may be inappropriate for very short measurement campaigns. Attempting to fit a representative daily trend to one or two days’ measurements may lead to a high degree of uncertainty; inclusion of a yearly trend requires having at least a year’s worth of data with few gaps, particularly large gaps. In such a situation, the temporal trends may end up being penalised to zero and the model reverts to one largely influenced by meteorology.

A review of commuter exposure to ultrafine particles and its health effects

Abstract: Ultrafine particles (UFPs, <100 nm) are produced in large quantities by vehicular combustion and are implicated in causing several adverse human health effects. Recent work has suggested that a large proportion of daily UFP exposure may occur during commuting. However, the determinants, variability and transport mode-dependence of such exposure are not well-understood. The aim of this review was to address these knowledge gaps by distilling the results of ‘in-transit’ UFP exposure studies performed to-date, including studies of health effects. We identified 47 exposure studies performed across 6 transport modes: automobile, bicycle, bus, ferry, rail and walking. These encompassed approximately 3000 individual trips where UFP concentrations were measured. After weighting mean UFP concentrations by the number of trips in which they were collected, we found overall mean UFP concentrations of 3.4, 4.2, 4.5, 4.7, 4.9 and 5.7 × 10^4 particles cm^-3 for the bicycle, bus, automobile, rail, walking and ferry modes, respectively. The mean concentration inside automobiles travelling through tunnels was 3.0 × 10^5 particles cm^-3. While the mean concentrations were indicative of general trends, we found that the determinants of exposure (meteorology, traffic parameters, route, fuel type, exhaust treatment technologies, cabin ventilation, filtration, deposition, UFP penetration) exhibited marked variability and mode-dependence, such that it is not necessarily appropriate to rank modes in order of exposure without detailed consideration of these factors. Ten in-transit health effects studies have been conducted and their results indicate that UFP exposure during commuting can elicit acute effects in both healthy and health-compromised individuals. We suggest that future work should focus on further defining the contribution of in-transit UFP exposure to total UFP exposure, exploring its specific health effects and investigating exposures in the developing world. Keywords: air pollution; transport modes; acute health effects; travel; public transport

Association between indoor air pollution measurements and respiratory health in women and children in Lao PDR.

Abstract: This article presents the results of a study on the association between measured air pollutants and the respiratory health of resident women and children in Lao PDR, one of the least developed countries in Southeast Asia. The study, commissioned by the World Health Organisation, included PM10, CO and NO2 measurements made inside 181 dwellings in nine districts within two provinces in Lao PDR over a 5- month period (12/05–04/06), and respiratory health information (via questionnaires and peak expiratory flow rate (PEFR) measurements) for all residents in the same dwellings. Adjusted odds ratios were calculated separately for each health outcome using binary logistic regression. There was a strong and consistent positive association between NO2 and CO for almost all questionnaire-based health outcomes for both women and children. Women in dwellings with higher measured NO2 had more than triple of the odds of almost all of the health outcomes, and higher concentrations of NO2 and CO were significantly associated with lower PEFR. This study supports a growing literature confirming the role of indoor air pollution in the burden of respiratory disease in developing countries. The results will directly support changes in health and housing policy in Lao PDR.

Role of vegetation in enhancing radon concentration and ion production in the atmosphere

Abstract: The role of ions in the production of atmospheric particles has gained wide interest due to their profound impact on climate. Away from anthropogenic sources, molecules are ionized by alpha radiation from radon exhaled from the ground and cosmic gamma radiation from space. These molecular ions quickly form into ‘cluster ions’, typically smaller than about 1.5 nm. Using our measurements and the published literature, we present evidence to show that cluster ion concentrations in forest areas are consistently higher than outside. Since alpha radiation cannot penetrate more than a few centimetres of soil, radon present deep in the ground cannot directly contribute to the measured cluster ion concentrations. We propose an additional mechanism whereby radon, which is water soluble, is brought up by trees and plants through the uptake of groundwater and released into the atmosphere by transpiration. We estimate that, in a forest comprising eucalyptus trees spaced 4m apart, approximately 28% of the radon in the air may be released by transpiration. Considering that 24% of the earth’s land area is still covered in forests; these findings have potentially important implications for atmospheric aerosol formation and climate.

Pollutant concentrations within households in Lao PDR and association with housing characteristics and occupants' activities.

Abstract: The paper presents the results of a study conducted to investigate indoor air quality within residential dwellings in Lao PDR. Results from PM(10), CO, and NO(2) measurements inside 167 dwellings in Lao PDR over a five month period (December 2005-April 2006) are discussed as a function of household characteristics and occupant activities. Extremely high PM(10) and NO(2) concentrations (12 h mean PM(10) concentrations 1275 ± 98 μg m(-3) and 1183 ± 99 μg m(-3) in Vientiane and Bolikhamxay provinces, respectively; 12 h mean NO(2) concentrations 1210 ± 94 μg m(-3) and 561 ± 45 μg m(-3) in Vientiane and Bolikhamxay, respectively) were measured within the dwellings. Correlations, ANOVA analysis (univariate and multivariate), and linear regression results suggest a substantial contribution from cooking and smoking. The PM(10) concentrations were significantly higher in houses without a chimney compared to houses in which cooking occurred on a stove with a chimney. However, no significant differences in pollutant concentrations were observed as a function of cooking location. Furthermore, PM(10) and NO(2) concentrations were higher in houses in which smoking occurred, suggestive of a relationship between increased indoor concentrations and smoking (0.05 < p < 0.10). Resuspension of dust from soil floors was another significant source of PM(10) inside the house (634 μg m(-3), p < 0.05).

Association between indoor air pollution measurements and respiratory health in women and children in Lao PDR

Abstract: This article presents the results of a study on the association between measured air pollutants and the respiratory health of resident women and children in Lao PDR, one of the least developed countries in Southeast Asia. The study, commissioned by the World Health Organisation, included PM10, CO and NO2 measurements made inside 181 dwellings in nine districts within two provinces in Lao PDR over a 5- month period (12/05–04/06), and respiratory health information (via questionnaires and peak expiratory flow rate (PEFR) measurements) for all residents in the same dwellings. Adjusted odds ratios were calculated separately for each health outcome using binary logistic regression. There was a strong and consistent positive association between NO2 and CO for almost all questionnaire-based health outcomes for both women and children. Women in dwellings with higher measured NO2 had more than triple of the odds of almost all of the health outcomes, and higher concentrations of NO2 and CO were significantly associated with lower PEFR. This study supports a growing literature confirming the role of indoor air pollution in the burden of respiratory disease in developing countries. The results will directly support changes in health and housing policy in Lao PDR.

Regulations and policy measures related to the reduction of ambient particulate matter

Abstract: The aim of this paper was to review the existing regulations and policy measures related to the reduction of airborne particulate matter, which is perhaps the most complex airborne pollutant to understand and manage. The paper discusses the existing health guidelines for particulate matter concentration, as well as the directions in setting national standards. In relation to particle mass concentration, there are no threshold levels, nor is there a linear exposure-health response relationship. At this point in time, epidemiological studies are yet to provide any quantification of exposure-response relationships in relation to particle number concentration (ultrafine particles), and the only existing number concentration standards are for clean rooms. Motor vehicle emission standards are generally provided in terms of total particle mass emissions, however, for light-duty diesel vehicles, a particle number limit has recently been introduced, whereas standards relating to industrial emissions commonly regulate total emissions of particulate matter. There are many other sources of airborne particulate matter, including aviation, shipping, biomass combustion or waste incineration, which are not directly regulated in terms of particle emissions.

CO2 emissions from the combustion of native Australian trees

Abstract: Carbon dioxide (CO2), as a primary product of combustion, is a known factor affecting climate change and global warming. In Australia, CO2 emissions from biomass burning are a significant contributor to total carbon in the atmosphere and therefore, it is important to quantify the CO2 emission factors from biomass burning in order to estimate their magnitude and impact on the Australian atmosphere. This paper presents the quantification of CO2 emission factors for five common tree species found in South East Queensland forests, as well as several grasses taken from savannah lands in the Northern Territory of Australia, under controlled ‘fast burning’ and ‘slow burning’ laboratory conditions. The results showed that CO2 emission factors varied according to the type of vegetation and burning conditions, with emission factors for fast burning being 2574 ± 254 g/kg for wood, 394 ± 40 g/kg for branches and leaves, and 2181 ± 120 g/kg for grass. Under slow burning conditions, the CO2 emission factors were 218 ± 20 g/kg for wood, 392± 80 g/kg for branches and leaves, and 2027 ± 809 g/kg for grass.

An Investigation of Commuter Exposure to Ultrafine Particles in Sydney

Abstract: Commuting in various transport modes represents an activity likely to incur significant exposure to traffic emissions. This study investigated the determinants and characteristics of exposure to ultrafine (< 100 nm) particles (UFPs) in four transport modes in Sydney, with a specific focus on exposure in automobiles, which remain the transport mode of choice for approximately 70% of Sydney commuters. UFP concentrations were measured using a portable condensation particle counter (CPC) inside five automobiles commuting on above ground and tunnel roadways, and in buses, ferries and trains. Determinant factors investigated included wind speed, cabin ventilation (automobiles only) and traffic volume. The results showed that concentrations varied significantly as a consequence of transport mode, vehicle type and ventilation characteristics. The effects of wind speed were minimal relative to those of traffic volume (especially heavy diesel vehicles) and cabin ventilation, with the latter proving to be a strong determinant of UFP ingress into automobiles. The effect of 70 minutes of commuting on total daily exposure was estimated using a range of UFP concentrations reported for several microenvironments. A hypothetical Sydney resident commuting by automobile and spending 8.5 minutes of their day in the M5 East tunnel could incur anywhere from a lower limit of 3-11% to an upper limit of 37-69% of daily UFP exposure during a return commute, depending on the concentrations they encountered in other microenvironments, the type of vehicle they used and the ventilation setting selected. However, commute-time exposures at either extreme of the values presented are unlikely to occur in practice. The range of exposures estimated for other transport modes were comparable to those of automobiles, and in the case of buses, higher than automobiles.

The Effect of indoor and outdoor particle sources on indoor air quality of a new multilevel office building in the vicinity of a busway

Abstract: Indoor air quality is very important for office workers’ exposure levels. There is a large body of literature showing that pollutants in indoor air have an effect on health (Sundell, 2008), with cardiovascular and respiratory disorders often linked to particle exposure. Other responses, such as damage to the central nervous system by ultrafine particles (UFP), have also been suggested. Both indoor and outdoor particle sources can affect indoor particle concentration levels, however these effects could be influenced by variety conditions and may be building-specific. This study investigated indoor and outdoor (I/O) particle concentration levels and diurnal variations, as well as the effect of indoor and outdoor particle sources on indoor air quality in a new four level office building, with an elevated busway in close proximity (about 10 m) to the air intake of the building’s ventilation system. Further to this, size dependent filtration efficiencies for two of the existing HVAC systems were also tested.

The Effect of Indoor and Outdoor Sources and House Characteristics on Indoor Airborne Particles and NO2

Abstract: As part of a larger indoor environmental study, residential indoor and outdoor 48-hour average levels of nitrogen dioxide (NO2), 48-hour indoor submicrometer particle number (0.007-0.808) concentration and the approximation of particle mass (PM2.5) concentrations were measured simultaneously for 14 houses in a suburb of Brisbane, Queensland, Australia. These pollutants were also measured at two central monitoring stations, a few kilometres from the suburb. Statistical analyses of the correlation between indoor and outdoor pollutants, and the association between house characteristics and indoor pollutants were conducted.