[P3703] Oxidative properties of PM2.5 in the European community respiratory health survey cities (ECRHS)

N. Künzli,^1,4 T. Shi,² T. Gotschi,^1,4 F. Kelly,³ J. Heinrich,⁴ B. Forsberg,⁴ D. Jarvis,^3,4 D. Norback,⁴ M. Hazenkamp,⁴ P. Borm.². ¹USC, Los Angeles, United States of America; ²IUF, Duesseldorf, Germany; ³KCL, London, United Kingdom; ⁴European Comm Respir Health Survey, ECRHS, United Kingdom

We hypothesize that the capacity of fine particles (PM2.5) to generate hydroxyl radicals ( OH) and/or deplete ascorbate (ASC) are biologically relevant properties that vary across cities, independently from mass. We measured oxidative properties (OxP) in a standard mass, from 720 daily PM2.5 samples (20 locations). OH generation was measured by electron magnetic resonance (ESR). ASC depletion was assessed in a synthetic model of lung lining fluid (200UM of ASC, GSH and urate). OxP strongly varied across Europe (OH signal: 7-fold range; ASC:<30% - >80% depletion). Samples from Galdakao and Paris displayed the greatest OxP, up to 8x the OH signal observed in Reykjavik; up to 3 times higher ASC depletion rates (in %) than in Norwich or Erfurt. The rank correlation between mean PM2.5 and OxP was <0.25. OH and ASC cross-city correlations were 0.61. The temporal ASC variability was very high in some cities (eg. Norwich, Oviedo) but not in all. Spatial variability across 2 stations (Antwerp,9 km apart) was 0.93 for PM2.5, 0.54 for black smoke, and 0.55 for OH. We conclude that OxP of PM2.5 vary substantially across Europe. Long-term mean concentrations of PM2.5 are not a surrogate of OxP. Within-city spatial variability appeared to be similar to other surrogates, successfully used in epidemiological studies. Epidemiological investigations of long-term effects of PM may benefit from taking both, mass and OxP into account. Keywords: epidemiology, questionnaires; occupation, pollution