Community Research and Development Information Service - CORDIS

Final Activity Report Summary - ERITASK (Environmental research institute transfer of atmospheric science knowledge)

The main scientific objectives were to characterise the processes that produce 'fine' (PM2.5) particles in Cork rural / urban air during 2005/2006 and to try to determine their toxicity as a function of chemical composition. The importance of the different source categories was also explored. Four postdoctoral fellows were employed for this purpose: the first with field measurement expertise; the second researcher had a specific background in inorganic and organic chemical analysis; the third individual possessed chemometrics experience especially in the area of source apportionment modelling to bring together the field and analysis data. The fourth possessed a biochemistry background with toxicology experience in assessing the metabolites involved in the exposure of human tissue to various PM-related chemicals.

In addition, we were able to recruit, from Irish national funds, four doctoral students to participate in the TOK activities to embed the research topic into University College Cork. PM2.5 was collected at three sites representative of the southern Irish atmosphere; a central urban site (City) an urban background site (UBS) and a rural site (RS) over the four seasons. At the city site more than 50 % of particulates were closer to the accumulation range / transient nuclei or Aitken nuclei size range irrespective of season and were comprised predominately of chain like soot aggregates. Elemental composition studies clearly indicated spatial and seasonal variation; all samples contained varying levels of total carbon but levels were highest at the city site during the winter season. Higher transition metal concentrations were evident at the city and UBS sites. A good agreement was noted between total sulphur and sulphate at both the UBS and rural sites, whereas the city site correlation suggested that sulphur exists in other forms such as metal sulphides. A significant increase in total Polyaromatic hydrocarbons (PAH) concentration from summer to autumn/winter was also found. This marked increase is probably due to increased emissions from home heating during the colder months.

One noteworthy observation is that the concentration of naphthalene seems elevated when compared with other low molecular weight PAHs. The greatest average concentrations of alkanes were found at the city location with carbon chain maximums (Cmax) at pentacosane indicating a strong traffic contribution. However, the averages plotted for the summertime rural location suggest a stronger biogenic contribution by plant wax.

The results obtained also showed a significant seasonal variation with the maximum total concentration during the winter / spring seasons and the minimum total concentration in summer. Attention was then focused on the interaction between PM and lung cells. Human lung epithelial cells, A549, were treated with PM2.5 and different toxicological end points were evaluated. These were:
(i) reactive oxygen species;
(ii) DNA damage / genotoxicity;
(iii) cytotoxicity;
(iv) inflammatory potential;
(v) endotoxin content.
All samples induced intracellular ROS and release of (interleukin) IL-6 and IL-8. The city samples showed a consistent ability to increase the production of intracellular ROS irrespective of the season. Samples collected during the summer season at all sites were the most potent stimulators for IL-6 release. Chemometrics was used to test for correlations between viability, cytokine release and the induction of ROS with the concentrations of 24 elements and 10 ions. Four principle components accounted for three quarters of the variance.

The results indicate that transition element components in particles could play an important role in causing the seasonal and geographical variations in PM-induced health effects related to respiratory illnesses. Specifically, for the organic compounds (quinones) the urban locations during the autumn season generated the largest response followed closely by that recorded for the winter urban samples.

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