Browsing by Author "Morawska, L"

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    Airborne ultrafine particles in a Pacific Island country: characteristics, sources and implications for human exposure
    (Elsevier, 2017-09-25) Isley, CF; Nelson, PF; Taylor, MP; Mazaheri, M; Morawska, L; Atanacio, AJ; Stelcer, E; Cohen, DD; Morrison, AL
    The Pacific Islands carry a perception of having clean air, yet emissions from transport and burning activities are of concern in regard to air quality and health. Ultrafine particle number concentrations (PNCs), one of the best metrics to demonstrate combustion emissions, have not been measured either in Suva or elsewhere in the Islands. This work provides insight into PNC variation across Suva and its relationship with particle mass (PM) concentration and composition. Measurements over a short monitoring campaign provide a vignette of conditions in Suva. Ambient PNCs were monitored for 8 day at a fixed location, and mobile PNC sampling for two days. These were compared with PM concentration (TSP, PM10, PM2.5, PM1) and are discussed in relation to black carbon (BC) content and PM2.5 sources, determined from elemental concentrations; for the October 2015 period and longer-term data. Whilst Suva City PM levels remained fairly low, PM2.5 = 10–12 μg m−3, mean PNC (1.64 ± 0.02 × 104 cm−3) was high compared to global data. PNCs were greater during mobile sampling, with means of 10.3 ± 1.4 × 104 cm−3 and 3.51 ± 0.07 × 104 cm−3 when travelling by bus and taxi, respectively. Emissions from road vehicles, shipping, diesel and open burning were identified as PM sources for the October 2015 period. Transport related ultrafine particle emissions had a significant impact on microscale ambient concentrations, with PNCs near roads being 1.5 to 2 times higher than nearby outdoor locations and peak PNCs occurring during peak traffic times. Further data, particularly on transport and wet-season exposures, are required to confirm results. Understanding PNC in Suva will assist in formulating effective air emissions control strategies, potentially reducing population exposure across the Islands and in developing countries with similar emission characteristics. Suva's PNC was high in comparison to global data; high exposures were related to transport and combustion emissions, which were also identified as significant PM2.5 sources. © 2017 Elsevier Ltd.
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    Elemental composition of ambient fine particles in urban schools : sources of children’s exposure
    (Aerosol and Air Quality Research, 2014-12-01) Crilley, LR; Ayoko, GA; Stelcer, E; Cohen, DD; Morawska, L
    Currently, there is a limited understanding of the sources of ambient fine particles that contribute to the exposure of children at urban schools. Since the size and chemical composition of airborne particle are key parameters for determining the source as well as toxicity, PM1 particles (mass concentration of particles with an aerodynamic diameter less than 1 µm) were collected at 24 urban schools in Brisbane, Australia and their elemental compositions determined. Based on the elemental compositions four main sources were identified; secondary sulphates, biomass burning, vehicle and industrial emissions. While secondary sulphates were likely to be a large contributing source by mass, industrial emissions accounted for the most variation in trace metals in the PM1 that children were exposed to at the schools. PM1 concentrations at the schools were compared to the elemental composition of the PM2.5 particles (mass concentration of particles with an aerodynamic diameter less than 2.5 µm) from a previous study conducted at a suburban and roadside site in Brisbane. This comparison suggested that the more toxic heavy metals (V, Cr, Ni, Cu, Zn and Pb), mostly from vehicle and industrial emissions, were predominantly in the PM1 fraction. Thus, the results from this study points to PM1 as a potentially good particle size fraction for investigating the health effects of airborne particles. Further work is required to confirm this hypothesis. © 2014 Taiwan Association for Aerosol Research
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    Relating urban airborne particle concentrations to shipping using carbon based elemental emission ratios
    (Elsevier, 2014-10) Johnson, GR; Juwono, AM; Friend, AJ; Cheung, HC; Stelcer, E; Cohen, DD; Ayoko, GA; Morawska, L
    This study demonstrates a novel method for testing the hypothesis that variations in primary and secondary particle number concentration (PNC) in urban air are related to residual fuel oil combustion at a coastal port lying 30 km upwind, by examining the correlation between PNC and airborne particle composition signatures chosen for their sensitivity to the elemental contaminants present in residual fuel oil. Residual fuel oil combustion indicators were chosen by comparing the sensitivity of a range of concentration ratios to airborne emissions originating from the port. The most responsive were combinations of vanadium and sulphur concentration ([S], [V]) expressed as ratios with respect to black carbon concentration ([BC]). These correlated significantly with ship activity at the port and with the fraction of time during which the wind blew from the port. The average [V] when the wind was predominantly from the port was 0.52 ng m−3 (87%) higher than the average for all wind directions and 0.83 ng m−3 (280%) higher than that for the lowest vanadium yielding wind direction considered to approximate the natural background. Shipping was found to be the main source of V impacting urban air quality in Brisbane. However, contrary to the stated hypothesis, increases in PNC related measures did not correlate with ship emission indicators or ship traffic. Hence at this site ship emissions were not found to be a major contributor to PNC compared to other fossil fuel combustion sources such as road traffic, airport and refinery emissions. © 2014, Elsevier Ltd.