Showing papers by "Lidia Morawska published in 2002"

Effect of face velocity and the nature of aerosol on the collection of submicrometer particles by electrostatic precipitator.

Abstract: Despite the electrostatic collection of aerosol particles is one of the most widely used air cleaning methods, there have not been sufficient amount of effort devoted to investigate its performance in the full range of operating conditions. This paper reports results of the tests of a two-stage electrostatic precipitator (ESP) conducted in the particle size range of 0.018 - 1.2m over a range of flow rates using NaCl and Environmental Tobacco Smoke (ETS) test aerosols. The total collection efficiency of the precipitator was found to increase with an increase in the count median diameter (CMD) of the particles, to have polynomial dependence on flow rate and no significant dependence on the type of test aerosol. The fractional efficiency of the precipitator was found to be dependent on flow rate. However, the “critical” particle size of about 1.2 m was found to exist when the fractional collection efficiency becomes independent of flow rate. For submicrometer particles, the collection efficiency was found to be independent of particle size at flow rates below 560 L.s-1. A minimum in the efficiency was observed in the 0.1 to 0.45 m particle size range and for particles smaller than about 0.02 m.

Methodologies for characterisation of combustion sources and for quantification of their emissions

Abstract: Emissions from the combustion of biomass and fossil fuels result in generation of a large number of particle and gaseous products in outdoor and/or indoor air, which create health and environmental risks. Of particular importance are the very small particles that are emitted in large quantities from all the combustion sources, and that could be potentially more significant in terms of their impact on health and the environment than larger particles. It is important to quantify particle emissions from combustion sources for regulatory and control purposes in relation to air quality. This paper is a review of particle characteristics that are used as source signatures, their general advantages and limitations, as well as a review of source signatures of the most common combustion pollution sources including road transport, industrial facilities, small household combustion devices, environmental tobacco smoke, and vegetation burning. The current methods for measuring particle physical characteristics (mass and number concentrations) and principles of methodologies for measuring emission factors are discussed in the paper as well. Finally, the paper presents the recommendations for the future techniques for measurements of combustion products.

Dispersion of particles from vehicle emissions around high- and low-rise buildings.

Abstract: Understanding the distribution of outdoor pollutants around a building envelope, generated by sources located in its vicinity, is important for choosing the location of building ventilation system intakes, as well as for quantifying the exposure of people living or working in the building. A systematic experimental characterisation of the number concentration of submicrometre particles was undertaken around the envelope of six buildings (both low- and high-rise) at different distances from a road, (the main pollution source). The concentrations were measured using two TSI Scanning Mobility Particle Sizers. PM2.5 concentrations were also monitored around the low-rise buildings using two TSI DustTraks. For the three high rise buildings the concentration of fine and ultra-fine particles decreased in most cases to about 50 - 60% from the approximate ground level readings (between heights of 0 to 6 m), to full building height (from 24 to 33 m above the ground). Measurements of submicrometre particle number concentrations as well as PM2.5 fraction in the envelope around low-rise isolated buildings did not show any significant trends from the front to the rear of the building. The sensitivity of PM2.5 measurements to a small number of larger particles, possibly from sources other than vehicle emissions, was observed.

Modelling of Particle Emissions from Motor Vehicles in Urban Environments

Abstract: Air quality impacts of urban transportation policies and strategies are often assessed using modelling techniques based on traffic flow simulation and travel demand analysis tools. Such analytical methods have traditionally been aimed at estimating the overall mass of individual pollutants with an emphasis on gaseous emissions. Significantly less attention is usually given to the quantification of particle emissions. Extensive data relating to fine and ultra-fine airborne particle concentration levels and the corresponding contributing vehicles have been collected at two significantly different Brisbane sites. Analysis of the relationships between the data so far point to a strong correlation between traffic flow and meteorological variables and particle concentrations.

The evaluation of air quality impacts of traffic on urban road networks

Abstract: Air quality impacts of urban transportation policies and strategies are often assessed using modelling techniques based on traffic flow simulation and travel demand analysis tools Such analytical methods have traditionally been aimed at estimating the overall mass of individual pollutants with an emphasis on gaseous emissions Significantly less attention is usually given to the quantification of particle emissions Extensive data relating to fine and ultra-fine airborne particle concentration levels and the corresponding contributing vehicles have been collected at two significantly different Brisbane sites Analysis of the relationships between the data so far point to a strong correlation between traffic flow and meteorological variables and particle concentrations

New Directions: Particle Air Pollution Down Under.

Abstract: Flying across the oceans separating the continents of the Southern Hemisphere the traveller often develops almost a physical feeling of distance and space. However, it is not only nature that astonishes with its grandness Down Under: human problems and the catastrophic effects of human actions are on a grand scale as well. These include air pollution and its two major sources: fires and motor vehicles. It is not an uncommon, but often frightening view travelling somewhere between Australia and Asia to be surrounded by a large plume of smoke hiding the sun that should normally shine through the window when flying at these altitudes. At the same time blue sky is an uncommon view over most megacities of the Southern Hemisphere.

Modelling of Particle Concentrations from Motor Vehicles in Urban Environments

Abstract: Air quality impacts of urban transportation policies and strategies are often assessed using modelling techniques based on traffic flow simulation and travel demand analysis tools. Such analytical methods have traditionally been aimed at estimating the overall mass of individual pollutants with an emphasis on gaseous emissions. Significantly less attention is usually given to the quantification of particle emissions. Extensive data relating to fine and ultra-fine airborne particle concentration levels and the corresponding contributing vehicles have been collected at two significantly different Brisbane sites. Analysis of the relationships between the data so far point to a strong correlation between traffic flow and meteorological variables and particle concentrations. (a) For the covering entry of this conference, please see ITRD abstract no. E206301.

Characterisation of filter performance in relation to outdoor air quality

Abstract: Airborne particle size distribution depends on the type of source from which the particles originate - filtration efficiency in turn, is dependent on particle size. Thus, in order to optimise filtration efficiency, it is important to gain knowledge on both: the size distribution of particles in the air to be filtered and the relationship between filtration efficiency and particle size. In addition, assessment needs to be made about the expected concentration level of particles around the building envelope and its time variation. This information is necessary for selecting the most suitable type of filters for the characteristics of particles that dominate in outdoor air.