title: Do bullae and emphysema increase risk of pneumothorax in silicosis?
abstract: BACKGROUND
  The occurrence of occupational lung diseases is decreasing due to improvements in occupational health in recent years; however, silicosis and its complications remain important occupational health problems. We have studied the role of emphysema and bullae as predictive factors of secondary spontaneous pneumothorax in acute and accelerated silicosis.
  
  
  METHODS
  This study was carried out using questionnaire items on occupational history and conventional computed tomography of lungs. Differences between two groups (silicosis with and without secondary spontaneous pneumothorax) in terms of age, interval of exposure-diagnosis and therefore silica exposure duration were assessed by independent t-test. Fisher's exact test was used to determine the association between secondary spontaneous pneumothorax and both emphysema and bullae.
  
  
  RESULTS
  We found a significant association between secondary spontaneous pneumothorax and bullae in acute and accelerated silicosis.
  
  
  CONCLUSIONS
  Pneumothorax in silicosis could be attributed to previous bullae.
authors.affiliation: Department of Occupational Medicine, Urmia University of Medical Sciences, Urmia, Iran. irajmohebbi@umsu.ac.ir.
authors.forename: Iraj
authors.initials: I
authors.lastname: Mohebbi
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Hassani
authors.forename: Shaker
authors.initials: S
authors.lastname: Salarilak
authors.forename: Abdul Rahman
authors.initials: AR
authors.lastname: Bahrami