title: Small pneumoconiotic opacities on U.S. coal worker surveillance chest radiographs are not predominantly in the upper lung zones.
abstract: BACKGROUND
  Radiographic shadows of coal workers' pneumoconiosis (CWP) are commonly described as predominantly in the upper lung zones.
  
  
  METHODS
  We evaluated the lung distribution of small opacities on surveillance chest radiographs (CXRs) taken between 1981 and 2010 among 2,467 underground US coal miners. All had evidence of pneumoconiosis (category ≥1/0), based on the contemporary International Labour Office Classification of Radiographs of Pneumoconioses.
  
  
  RESULTS
  Small opacity involvement was approximately equal over all lung zones, with 30.7% of the total involvement reported in the upper zones, 37.1% in the middle zones, and 32.1% in the lower zones. Primarily rounded opacities were seen in 62.1% of miners and primarily irregular opacities were seen in 37.9%. Miners with primarily rounded opacities had a distribution with moderate upper zone predominance (upper = 36.8%, middle = 36.5%, and lower = 27.2%). In contrast, miners with primarily irregular opacities showed a lower zone preponderance (upper = 20.5%, middle = 38.4%, and lower = 41.1%).
  
  
  CONCLUSIONS
  The distribution of small pneumoconiotic opacities on surveillance CXRs of working US coal miners is not consistent with the conventional expectations of upper lung zone predominance.
authors.affiliation: Surveillance Branch, Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA. alaney@cdc.gov
authors.forename: A Scott
authors.initials: AS
authors.lastname: Laney
authors.forename: Edward L
authors.initials: EL
authors.lastname: Petsonk
mesh_terms: D000328:Adult; D000368:Aged; D055008:Anthracosis / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011859:Radiography; D014481:United States