Linking urban air field measurements of particulate matter to their
Urban Air Field Measurements of Particulate Matter
Linking Urban Air Field Measurements of Particulate Matter to their Chemical Analysis and Effects on Health
Researcher: David Healy
Telephone number: 021 4903526
Funding Body: EPA
Project type: PhD
Period: 2003 - present
The need to measure the occurrence and development of particulate matter (PM) in our atmosphere has increased dramatically in recent years. The necessity is based both on the undesirable effects they have on our health and the role they play in climate change. Currently we do not possess a precise understanding of how PM participates in the cause and effect of these processes but it is clear that simply measuring particulate mass is not sufficient to provide a basis for assessing, and then limiting, their impact. Many other features such as size, shape, density and chemical/biological composition need to be analysed before accurate hazard assessments can be made as a prelude to drafting appropriate legislation for ambient and workplace environments. In fact the Clean Air for Europe (CAFÉ) Programme of the European Commission has recently estimated that current exposures to anthropogenic ambient fine Particulate Matter (PM2.5; particle size < 2.5 µm) air pollution in the 25 EU Member States cause annually about 350,000 premature deaths and a substantial restriction of normal life among tens of millions of subjects with chronic respiratory or cardiovascular disease. The annual costs of health damage were estimated at 270–780 billion euros. Hence the EPA in Ireland has developed funding strands in its research programme to address the challenges that we face in the whole area of “Environment and Health”.
My research project is the first of its kind in Ireland to encompass the four necessary stages to fully characterize airborne PM2.5 and to provide an assessment of the toxic potential of the pollutants as a function of chemical composition, season and location. Four main stages have been involved: 1. Sampling; 2. Physico-chemical compositional analysis; 3. Toxicological studies; 4. Chemometrics/source apportionment. My research has mainly concentrated on studies related to the elemental components of the PM2.5.
PM2.5 (particulate matter with a diameter 2.5 microns) was collected at three sites located throughout Cork, Ireland (Urban/City Centre, Urban Background and a Rural Site). The collections were made on Polyurethane Foam (PUF) filter substrates using a high volume cascade impactor sampler (900Lmin-1). Elemental concentrations of representative suites of 20 metals were determined using microwave extraction and ICP-OES spectrometry. In addition, aqueous extracts were analysed, after sequential agitation/sonication to quantify the solubility (bioavailability) of the different metal components (ICP-OES). This procedure was also utilised in the determination of the inorganic ion content of the PM2.5 by ion chromatography. The % total carbon was determined by use of a CE440 Elemental Analyser.
To investigate the biological effects of PM2.5 at a sub-cellular level, the human epithelial pulmonary A549 cell line was exposed for 72hrs to different concentrations of PM2.5 (0, 5.5, 11.0, 22.0 µg/cm2). As an index of cytotoxicity after PM2.5 exposure the activity of LDH released from the cytosol of damaged cells into the supernatant was determined using the appropriate colorimetric detection kit from Roche. In vitro cell proliferation and cytotoxicity after PM2.5 exposure has also been determined using the resazurin assay. A reduced glutathione (GSH) assay was employed to evaluate how GSH, one of the primary bio chemicals for cell defence, can be influenced by PM toxicity. In this study the ability of the 3 different concentrations to induce release of the pro-inflammatory cytokines interleukin-6 (IL-6) and interleukin-8 (IL-8) from human epithelial lung cells (A549) was investigated. The most potent samples exhibited a relatively high content of transition metals (e.g. Fe and Zn); this was especially true for the summer samples of the three sites when looking at IL-6. Significant cytotoxicity was noted only at higher concentrations of particle exposure which would indicate that chemical composition of PM2.5 is a critical determinant for the marked differences in potency to induce cytokine responses in human epithelial lung cells. A concentration dependence was noted for the toxicological assays: ROS (Reactive Oxygen Species), IL-6 and LDH. However the IL-8 response did not always increase with increasing particle dose over the 5.5-22.0 µg/cm2 range. In these cases, the decrease in IL-8 at higher particle concentrations could not be explained by loss of cell viability.
Applying linear regression analysis to the metals and ROS showed a positive correlation, and indicated a direct relation between transition metal content for the PM2.5 collections and ROS production
My overall project was integrally linked with an EU Marie Curie (Transfer of Knowledge) programme led by my supervisor Professor John Sodeau. I am indebted to the four postdoctoral Fellows who worked on this project (Dr Andrew Whittaker, Dr José Sebastian, Dr Virginia Silvari and Dr Emma Peré-Trepat) for “embedding” their knowledge and skills with me!
" Spectroscopic and Optimization Modeling study of Nitrous Acid in Aqueous Solution". E Riordan, N Minogue, D Healy, P O’Driscoll and J Sodeau. Journal of Physical Chemistry A, Volume 109, No.5, 779-786 2005
-The second annual "Environment Research Institute Day" of Ireland, 2/12/04, Aras na Mac Leinn, University College Cork, Ireland (Poster)
-"ERDTI Ph.D. Seminar 2005" , 29/9/05, Irish EPA headquarters, Co. Wexford, Ireland (Poster)
-“European research course on atmospheres 2006” 16/01/06 Université Joseph Fourier, Grenoble, France (Oral and Poster)
-COST Action 633 Particulate Matter: Properties related to health effects. International Conference. April 3-5 Austrian Academy of Sciences, Vienna, Austria 2006 (Poster)
-"ERDTI Ph.D. Seminar 2006" , 29/9/06, Irish EPA , Dublin, Ireland. (Oral)
- “Linking urban air field measurements of particulate matter to their chemical analysis and potential effects on health”. IGAC/CACGP/WMO Symposium Capetown. 2006 (Poster)
-Workshop on Environmental & Health: “Air Quality Research Needs and Opportunities in the EU Seventh Framework Programme of Research (FP7) 15-16 January 2007 Brussels, Belgium.
-6th International Conference on Urban Air Quality. 27-29 March 2007 Limmasol, Cyprus. (Poster)
-11th International Congress of Toxicology. 15-19 July 2007 Montreal, Canada. (Poster)
-European Aerosol Conference 2007.9th- 14th of September 2007. Faculty of Science, University of Salzburg, Hellbrunner Strasse 34, Salzburg, Austria. (Poster)
World Meteorological Organisation student bursary for the attendance to the Urban Air Quality Conference 2007, Limmasol Cyprus.
The Association of Aerosol Research (Gaef) student bursary for the attendance to the European Aerosol Conference 2007, Salzburg, Austria.