Background: When workplace air monitoring is not sufficient to determine the exposure levels, the determination of compounds and some metabolites in exhaled air and personal exposure levels is considered a practical method for biological monitoring. The aim of this study was to determine the relationship between the concentration of tetrachlorethylene in exhaled air and personal exposure levels in the dry cleaning workers
Methods: In this descriptive cross - sectional study was performed in 2017, in addition to the collecting samples of exhaled air and personal exposure of 12 workers, the ambient air samples of dry cleaning workplace were examined. Also the ambient air samples were studied simultaneously.  Measurement of tetrachlorethylene in the exhaled air was performed using gas chromatograph equipped with flame ionization detector (FID) through an incorporation of 1003 and 3704 NIOSH methods and optimization of analysis parameters.
Results: In this study, the personal exposure levels were above the recommended national occupational exposure limits (OEL-TWA), and tetrachlorethylene concentration in exhaled air of workers were above the biological exposure index (BEI) respectively. The results showed that there is a significant relationship between the concentration of tetrachlorethylene in exhaled air and personal exposure levels (r=0.66, P=0.046). Also, was obtained the significant relationship between the concentration of ambient air with exhaled air concentrations (r=0.59, P=0.003), and personal exposure levels (r=0.91, P<0.001) respectively.
Conclusion: The results indicated that tetrachlorethylene measuring in the exhaled air as a non-invasive biomarker is valid enough for assessing occupational exposure in the dry cleanings. And also tetrachlorethylene concentration in exhaled air can be measured with high sensitivity through optimizing of analytical conditions in GC-FID system and the integration of 1003 and 3704 NIOSH methods.