title: Associations of PM₂.₅ constituents and sources with hospital admissions: analysis of four counties in Connecticut and Massachusetts (USA) for persons ≥ 65 years of age.
abstract: BACKGROUND
  Epidemiological studies have demonstrated associations between short-term exposure to PM2.5 and hospital admissions. The chemical composition of particles varies across locations and time periods. Identifying the most harmful constituents and sources is an important health and regulatory concern.
  
  
  OBJECTIVE
  We examined pollutant sources for associations with risk of hospital admissions for cardiovascular and respiratory causes.
  
  
  METHODS
  We obtained PM2.5 filter samples for four counties in Connecticut and Massachusetts and analyzed them for PM2.5 elements. Source apportionment was used to estimate daily PM2.5 contributions from sources (traffic, road dust, oil combustion, and sea salt as well as a regional source representing coal combustion and other sources). Associations between daily PM2.5 constituents and sources and risk of cardiovascular and respiratory hospitalizations for the Medicare population (> 333,000 persons ≥ 65 years of age) were estimated with time-series analyses (August 2000-February 2004).
  
  
  RESULTS
  PM2.5 total mass and PM2.5 road dust contribution were associated with cardiovascular hospitalizations, as were the PM2.5 constituents calcium, black carbon, vanadium, and zinc. For respiratory hospitalizations, associations were observed with PM2.5 road dust, and sea salt as well as aluminum, calcium, chlorine, black carbon, nickel, silicon, titanium, and vanadium. Effect estimates were generally robust to adjustment by co-pollutants of other constituents. An interquartile range increase in same-day PM2.5 road dust (1.71 μg/m3) was associated with a 2.11% (95% CI: 1.09, 3.15%) and 3.47% (95% CI: 2.03, 4.94%) increase in cardiovascular and respiratory admissions, respectively.
  
  
  CONCLUSIONS
  Our results suggest some particle sources and constituents are more harmful than others and that in this Connecticut/Massachusetts region the most harmful particles include black carbon, calcium, and road dust PM2.5.
authors.affiliation: School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Bell
authors.forename: Keita
authors.initials: K
authors.lastname: Ebisu
authors.forename: Brian P
authors.initials: BP
authors.lastname: Leaderer
authors.forename: Janneane F
authors.initials: JF
authors.lastname: Gent
authors.forename: Hyung Joo
authors.initials: HJ
authors.lastname: Lee
authors.forename: Petros
authors.initials: P
authors.lastname: Koutrakis
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Francesca
authors.initials: F
authors.lastname: Dominici
authors.forename: Roger D
authors.initials: RD
authors.lastname: Peng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000209:etiology; D003237:Connecticut / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008404:Massachusetts / Q000453:epidemiology; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D012044:Regression Analysis; D012120:Respiration Disorders / Q000453:epidemiology* / Q000209:etiology; D014887:Weather
chemical_list: D052638:Particulate Matter