Data analysis We used Statistical Package for Social Sciences SPSS (version 14) and STATA package (version 9). Frequency distribution of independent variables (sociodemographic characteristics, work characteristics, PPE, and smoking habits) and
Data analysisWe used Statistical Package for Social Sciences SPSS (version14) and STATA package (version 9). Frequency distributionof independent variables (sociodemographic characteristics,work characteristics, PPE, and smoking habits) and