title: [Contribution of different sources of exposure to particulate matter in an elderly community in Tianjin].
abstract: OBJECTIVE
  To determine the pollution sources that influence the level of exposure to particulate matter 2.5 (PM2.5) in the elderly, and calculate the quantitative contributions of difference sources.
  
  
  METHODS
  Personal exposure PM samples were collected in the summer and winter of 2011 from 101 elderly men in a Tianjin community. Chemical species (elements, water-soluble ions and carbonaceous species) were analyzed in PM samples to determine PM2.5 concentrations and chemical compositions. The Positive Matrix Factorization (PMF) model, which is recommended by the US Environmental Protection Agency, was employed to quantitatively analyze the contribution of each potential sources to personal levels of PM2.5 exposure.
  
  
  RESULTS
  In both summer and winter, the model identified the same six sources of personal exposure to PM2.5 in the elderly: fugitive dust (marker species: Si, Al, Ca, Mg, Fe etc.), coal combustion emissions (marker species: organic carbon (OC) and SO4(2-)), vehicle exhausts (marker species: inorganic carbon and NO3-), secondary sulfates and nitrates (marker species: NO3-, SO42- and NH4(+)), industrial emissions (marker species: Mn, Ni, Cu, Zn, Pb etc.), and indoor sources (marker species: OC, K, Si, Al etc.). Among these six potential sources, vehicle exhausts (summer: 33.6%, winter: 24.2%), secondary sulfates and nitrates (summer: 27.4%, winter: 29.1%), as well as coal combustion emissions (summer: 19.9%, winter: 24.1%) were the greatest contributors.
  
  
  CONCLUSIONS
  Coal combustion and vehicle exhaust emissions were the major sources of personal exposure to PM2.5 in the elderly, suggesting that these two sources were the key contributors to the precursor gases of secondary sulfate and nitrate.
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: T R
authors.initials: TR
authors.lastname: Ni
authors.forename: B
authors.initials: B
authors.lastname: Han
authors.forename: P H
authors.initials: PH
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: N
authors.initials: N
authors.lastname: Zhang
authors.forename: L W
authors.initials: LW
authors.lastname: Zhang
authors.forename: Z P
authors.initials: ZP
authors.lastname: Bai
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D003031:Coal / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D003031:Coal; D052638:Particulate Matter; D001335:Vehicle Emissions