title: Oxidative potential of particulate matter collected at sites with different source characteristics.
abstract: BACKGROUND
  The oxidative potential (OP) of particulate matter (PM) has been proposed as a more health relevant metric than PM mass. Different assays exist for measuring OP and little is known about how the different assays compare.
  
  
  OBJECTIVE
  To assess the OP of PM collected at different site types and to evaluate differences between locations, size fractions and correlation with PM mass and PM composition for different measurement methods for OP.
  
  
  METHODS
  PM2.5 and PM10 was sampled at 5 sites: an underground station, a farm, 2 traffic sites and an urban background site. Three a-cellular assays; dithiothreitol (OP(DTT)), electron spin resonance (OP(ESR)) and ascorbate depletion (OP(AA)) were used to characterize the OP of PM.
  
  
  RESULTS
  The highest OP was observed at the underground, where OP of PM10 was 30 (OP(DTT)) to >600 (OP(ESR)) times higher compared to the urban background when expressed as OP/m(3) and 2-40 times when expressed as OP/μg. For the outdoor sites, samples from the farm showed significantly lower OP(ESR) and OP(AA), whereas samples from the continuous traffic site showed the highest OP for all assays. Contrasts in OP between sites were generally larger than for PM mass and were lower for OP(DTT) compared to OP(ESR) and OP(AA). Furthermore, OP(DTT)/μg was significantly higher in PM2.5 compared to PM10, whereas the reverse was the case for OP(ESR). OP(ESR) and OP(AA) were highly correlated with traffic-related PM components (i.e. EC, Fe, Cu, PAHs), whereas OP(DTT) showed the highest correlation with PM mass and OC.
  
  
  CONCLUSIONS
  Contrasts in OP between sites, differences in size fractions and correlation with PM composition depended on the specific OP assay used, with OP(ESR) and OP(AA) showing the most similar results. This suggests that either OP(ESR) or OP(AA) and OP(DTT) can complement each other in providing information regarding the oxidative properties of PM, which can subsequently be used to study its health effects.
authors: Department for Environmental Health, National Institute for Public Health and the Environment (RIVM), P.O. Box, 2720 BA, Bilthoven, The Netherlands. Electronic address: Nicole.Janssen@rivm.nl.
authors: Nicole A H
authors: NA
authors: Janssen
authors: Department for Environmental Health, National Institute for Public Health and the Environment (RIVM), P.O. Box, 2720 BA, Bilthoven, The Netherlands; Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, The Netherlands. Electronic address: Aileen.Yang@rivm.nl.
authors: Aileen
authors: A
authors: Yang
authors: Department for Environmental Health, National Institute for Public Health and the Environment (RIVM), P.O. Box, 2720 BA, Bilthoven, The Netherlands; Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, The Netherlands. Electronic address: MStrak@ggd.amsterdam.nl.
authors: Maciej
authors: M
authors: Strak
authors: Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, The Netherlands. Electronic address: M.Steenhof@uu.nl.
authors: Maaike
authors: M
authors: Steenhof
authors: Air Quality & Sustainable Nanotechnology, Institute of Energy and Environmental Technology (IUTA), Bliersheimer Straße 60, 47229 Duisburg, Germany. Electronic address: Hellack@iuta.de.
authors: Bryan
authors: B
authors: Hellack
authors: Department for Environmental Health, National Institute for Public Health and the Environment (RIVM), P.O. Box, 2720 BA, Bilthoven, The Netherlands. Electronic address: Miriam.Gerlofs@rivm.nl.
authors: Miriam E
authors: ME
authors: Gerlofs-Nijland
authors: Air Quality & Sustainable Nanotechnology, Institute of Energy and Environmental Technology (IUTA), Bliersheimer Straße 60, 47229 Duisburg, Germany. Electronic address: tky@iuta.de.
authors: Thomas
authors: T
authors: Kuhlbusch
authors: MRC-PHE Centre for Environment and Health, School of Biomedical Sciences, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom. Electronic address: Frank.Kelly@kcl.ac.uk.
authors: Frank
authors: F
authors: Kelly
authors: Division of Environmental Health & Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; Department of Environmental Sciences, Center of Excellence in Environmental Studies, King Abdulaziz University, P.O. Box 80216, Jeddah 21589, Saudi Arabia. Electronic address: R.M.HARRISON@bham.ac.uk.
authors: Roy
authors: R
authors: Harrison
authors: Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, The Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands. Electronic address: B.Brunekreef@uu.nl.
authors: Bert
authors: B
authors: Brunekreef
authors: Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, The Netherlands. Electronic address: G.Hoek@uu.nl.
authors: Gerard
authors: G
authors: Hoek
authors: Department for Environmental Health, National Institute for Public Health and the Environment (RIVM), P.O. Box, 2720 BA, Bilthoven, The Netherlands; Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, The Netherlands. Electronic address: Flemming.cassee@rivm.nl.
authors: Flemming
authors: F
authors: Cassee
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D010084:Oxidation-Reduction; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: 5,5-dimethylpyrroline-N-oxide; AA; AU; DMPO; DTT; ESR; GSH; HI; HVS; Harvard impactor; MOI; NAQMN; National Air Quality Monitoring Network; OP; Oxidative potential; PNC; Particulate matter; ROS; RTLF; Traffic; VACES; Versatile Aerosol Concentration Enrichment System; arbitrary units; ascorbic acid; dithiothreitol; electron spin resonance; glutathione; high volume sampler; micro-orifice impactor; oxidative potential; particle number concentration; reactive oxygen species; respiratory tract lining fluid