Population Attributable Fraction of Bronchial Anthracosis due to Smoke Exposure while Baking Home-made Bread in Ground Oven

Some case-report studies in Iran showed probable association between anthracosis and smoke exposure due to baking homemade bread, population. Therefore we estimated the population attributable fraction (PAF) for this probable association in Iranian population. A hospital-based case-control study, including 83 anthracotic subjects (cases) with 72 controls from surgical ward which were matched by age, conducted in Imam Khomeini hospital in Tehran (From September 2009 to December 2010). Patients in both case and control groups were interviewed according to "American Thoracic Society" guideline. Exposure to smoke was considered both as a binary and continuous variable (number of years being exposed to smoke) and the population attributable fraction (PAF) were estimated due to smoke exposure. Univariate analysis showed that exposure to smoke as binary variables, age and occupation exposure to dust and education were associated with anthracosis. After Adjusting, only smoke exposure (OR: 3.35, 95% CI: 1.49-7.55) remain significant. Univariate logistic regression model showed exposure to smoke as continuous variable has significant association with anthracosis. In multiple logistic model only duration (years) of smoke exposure remained significant (OR: 1.05, 95%CI: 1.01-1.09). PAF due to smoke exposure estimated approximately 48% in our population. Based on the findings of this study, it could be concluded that approximately half of the anthracotic cases are attributed to smoke exposure.