Comparison of oxidative properties, light absorbance, and total and elemental mass concentration of ambient PM2.5 collected at 20 European sites

Nino Künzli*, Ian S. Mudway, Thomas Götschi, Tingming Shi, Frank J. Kelly, Sarah Cook, Peter Burney, Bertil Forsberg, James W. Gauderman, Marianne E. Hazenkamp, Joachim Heinrich, Deborah Jarvis, Dan Norbäck, Felix Payo-Losa, Albino Poli, Jordi Sunyer, Paul J.A. Borm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

165 Citations (Scopus)


Objective: It has been proposed that the redox activity of particles may represent a major determinant of their toxicity. We measured the in vitro ability of ambient fine particles [particulate matter with aerodynamic diameters ≤ 2.5 μm (PM2.5)] to form hydroxyl radicals (OH) in an oxidant environment, as well as to deplete physiologic antioxidants (ascorbic acid, glutathione) in the naturally reducing environment of the respiratory tract lining fluid (RTLF). The objective was to examine how these toxicologically relevant measures were related to other PM characteristics, such as total and elemental mass concentration and light absorbance. Design: Gravimetric PM2.5 samples (n = 716) collected over 1 year from 20 centers participating in the European Community Respiratory Health Survey were available. Light absorbance of these filters was measured with reflectometry. PM suspensions were recovered from filters by vortexing and sonication before dilution to a standard concentration. The oxidative activity of these particle suspensions was then assessed by measuring their ability to generate OH in the presence of hydrogen peroxide, using electron spin resonance and 5,5-dimethyl-1-pyrroline-N-oxide as spin trap, or by establishing their capacity to deplete antioxidants from a synthetic model of the RTLF. Results and Conclusions: PM oxidative activity varied significantly among European sampling sites. Correlations between oxidative activity and all other characteristics of PM were low, both within centers (temporal correlation) and across communities (annual mean). Thus, no single surrogate measure of PM redox activity could be identified. Because these novel measures are suggested to reflect crucial biologic mechanisms of PM, their use may be pertinent in epidemiologic studies. Therefore, it is important to define the appropriate methods to determine oxidative activity of PM.

Original languageEnglish
Pages (from-to)684-690
Number of pages7
JournalEnvironmental Health Perspectives
Issue number5
Publication statusPublished - May 2006
Externally publishedYes


  • Air pollution
  • Antioxidant depletion
  • Ascorbate
  • Black smoke
  • Elemental analysis
  • Fine particle
  • Glutathione
  • Hydroxy redical formation
  • Oxidative stress
  • Reactive oxidant species
  • Reflectance


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