title: The oxidative potential of PM2.5 exposures from indoor and outdoor sources in rural China.
abstract: BACKGROUND
  Airborne particulate matter (PM) is a widespread environmental exposure and leading health risk factor. The health effects of PM may be mediated by its oxidative potential; however, the combustion and non-combustion sources and components of PM responsible for its oxidative potential are poorly understood, particularly in low- and middle-income rural settings where coal and biomass burning for cooking and heating contribute to PM exposure.
  
  
  METHODS
  We measured 24-h personal exposures to fine particulate matter (PM2.5) of 20 rural women in northern (Inner Mongolia) and southern (Sichuan) Chinese provinces who used solid fuels (i.e., coal, biomass). PM2.5 exposures were characterized for mass, black carbon, water-soluble organic carbon, major water-soluble ions, and 47 elements. The oxidative potential of PM2.5 exposures was measured using acellular (dithiothreitol-based) and cellular (macrophage-based) assays. We performed factor and correlation analyses using the chemical components of PM2.5 to identify sources of exposure to PM2.5 and their chemical markers. Associations between oxidative potential and chemical markers for major sources of PM2.5 exposure were assessed using linear regression models.
  
  
  RESULTS
  Women's geometric mean PM2.5 exposures were 249μgm(-3) (range: 53.9-767) and 83.9μgm(-3) (range: 73.1-95.5) in Inner Mongolia and Sichuan, respectively. Dust, biomass combustion, and coal combustion were identified as the major sources of exposure to PM2.5. Markers for dust (iron, aluminum) were significantly associated with intrinsic oxidative potential [e.g., one interquartile range increase in iron (ppm) was associated with an 85.5% (95% CI: 21.5, 149) increase in cellular oxidative potential (μgZymosanmg(-1))], whereas markers for coal (arsenic, non-sulfate sulfur) and biomass (black carbon, cadmium) combustion were not associated with oxidative potential.
  
  
  CONCLUSIONS
  Dust was largely responsible for the intrinsic oxidative potential of PM2.5 exposures of rural Chinese women, whereas biomass and coal combustion were not significantly associated with intrinsic oxidative potential.
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada; Institute for Health and Social Policy, McGill University, Montréal, Québec, Canada.
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Secrest
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin, Madison, WI, USA; Wisconsin State Laboratory of Hygiene, University of Wisconsin, Madison, WI, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Schauer
authors.affiliation: Institute on the Environment, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Ellison M
authors.initials: EM
authors.lastname: Carter
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin, Madison, WI, USA.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Lai
authors.affiliation: College of Resources and Environment, University of the Chinese Academy of Sciences, Beijing, China.
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Building Science, Tsinghua University, Beijing, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Shan
authors.affiliation: Department of Building Science, Tsinghua University, Beijing, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Yang
authors.affiliation: College of Resources and Environment, University of the Chinese Academy of Sciences, Beijing, China.
authors.forename: Yuanxun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada; Institute for Health and Social Policy, McGill University, Montréal, Québec, Canada; Institute on the Environment, University of Minnesota, Minneapolis, MN, USA. Electronic address: jill.baumgartner@mcgill.ca.
authors.forename: Jill
authors.initials: J
authors.lastname: Baumgartner
mesh_terms: D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D016902:Air Pollution, Indoor / Q000009:adverse effects / Q000032:analysis; D002681:China; D003296:Cooking; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005260:Female; D006361:Heating; D006801:Humans; D008875:Middle Aged; D018384:Oxidative Stress; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D012424:Rural Population
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Chemical speciation; Exposure assessment; Household air pollution; Reactive oxygen species; Redox activity; Solid fuel