[P3710] Location dependent differences in the capacity of European PM_2.5 to deplete respiratory tract lining fluid ascorbate

Frank J. Kelly,¹ Sarah Cook,¹ Thomas Gotschi,² Peter Burney,¹ Nino Kunzli.². ¹King's College London, London, United Kingdom; ²University of Southern California, Los Angeles, United States of America

The capacity of particulate matter (PM) to cause oxidative stress in the lung has been proposed to explain the toxicity of this pollutant. However whether oxidative activity represents a good predictor of PM-dependent health effects has not been addressed. Further, questions related to the existance of clear contrasts in PM activity between locations, or whether regional variation is greater than time dependent changes, are not known. To investigate these issues we utilised PM_2.5 samples collected in the European Community Respiratory Health Survey (ECHRS). Six sets of bi-monthly filters from 20 European locations (7-day collections) had their capacity to deplete ascorbate (Asc) from respiratory tract lining fluid (200μM of ascorbate, urate and gultathione, pH7) assessed at 50μg/ml. Individual sample activities ranged from Asc depletions of 91.1 (Turin) to 4.6% (Reykjavik), with a clear location hierachy apparent when individual site values were averaged. To demonstrate whether these differences were significant the 20 locations were categorised into activity quartiles (n=5) which depleted Asc by 71.3 (75.2-67.4), 58.0 (63.5-52.5), 46.1 (51.1-41.1) and 24.6 (30.4-18.8)% [mean with 95% CI] respectively. Each quartile was shown to differ significantly (P<0.05).We also noted that variation in bi-monthly samples within each quartile tended to increase as overall activity decreased, r=0.73, P<0.001. These data demonstrate clear location-dependent differences in PM activity even allowing for temporal variation. Keywords: occupation, pollution; pathophysiology