title: Air pollution and percent emphysema identified by computed tomography in the Multi-Ethnic study of Atherosclerosis.
abstract: BACKGROUND
  Air pollution is linked to low lung function and to respiratory events, yet little is known of associations with lung structure.
  
  
  OBJECTIVE
  We examined associations of particulate matter (PM2.5, PM10) and nitrogen oxides (NOx) with percent emphysema-like lung on computed tomography (CT).
  
  
  METHODS
  The Multi-Ethnic Study of Atherosclerosis (MESA) recruited participants (45-84 years of age) in six U.S. states. Percent emphysema was defined as lung regions < -910 Hounsfield Units on cardiac CT scans acquired following a highly standardized protocol. Spirometry was also conducted on a subset. Individual-level 1- and 20-year average air pollution exposures were estimated using spatiotemporal models that included cohort-specific measurements. Multivariable regression was conducted to adjust for traditional risk factors and study location.
  
  
  RESULTS
  Among 6,515 participants, we found evidence of an association between percent emphysema and long-term pollution concentrations in an analysis leveraging between-city exposure contrasts. Higher concentrations of PM2.5 (5 μg/m3) and NOx (25 ppb) over the previous year were associated with 0.6 (95% CI: 0.1, 1.2%) and 0.5 (95% CI: 0.1, 0.9%) higher average percent emphysema, respectively. However, after adjustment for study site the associations were -0.6% (95% CI: -1.5, 0.3%) for PM2.5 and -0.5% (95% CI: -1.1, 0.02%) for NOx. Lower lung function measures (FEV1 and FVC) were associated with higher PM2.5 and NOx levels in 3,791 participants before and after adjustment for study site, though most associations were not statistically significant.
  
  
  CONCLUSIONS
  Associations between ambient air pollution and percentage of emphysema-like lung were inconclusive in this cross-sectional study, thus longitudinal analyses may better clarify these associations with percent emphysema.
authors.affiliation: Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Sara D
authors.initials: SD
authors.lastname: Adar
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kaufman
authors.forename: Ana V
authors.initials: AV
authors.lastname: Diez-Roux
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hoffman
authors.forename: Jennifer
authors.initials: J
authors.lastname: D'Souza
authors.forename: Karen H
authors.initials: KH
authors.lastname: Stukovsky
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Rich
authors.forename: Jerome I
authors.initials: JI
authors.lastname: Rotter
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Guo
authors.forename: Leslie J
authors.initials: LJ
authors.lastname: Raffel
authors.forename: Paul D
authors.initials: PD
authors.lastname: Sampson
authors.forename: Assaf P
authors.initials: AP
authors.lastname: Oron
authors.forename: Trivellore
authors.initials: T
authors.lastname: Raghunathan
authors.forename: R Graham
authors.initials: RG
authors.lastname: Barr
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution / Q000009:adverse effects / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D004646:Emphysema / Q000139:chemically induced / Q000453:epidemiology*; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009589:Nitrogen Oxides / Q000009:adverse effects* / Q000032:analysis; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D013147:Spirometry; D014057:Tomography, X-Ray Computed; D014481:United States
chemical_list: D009589:Nitrogen Oxides; D052638:Particulate Matter