Background and aims: combined exposure to several threatening physical factors may impact on the performance negatively. With regard to the importance of the worker’s health and their optimum performance in addition to shortage of studies having dealt with the impacts of combined exposure on performance, this work was done with the purpose of studying the impacts of combined exposure to harmful and harmless levels of noise, heat and lighting.

Methods: This study was interventional with Factorial design. Where 128 subjects with ages 24-18 years were Participated Among the students of Shiraz University of Medical Sciences In 8 groups of 16 men and women No history of any mental illness and physical and drug consumption and narcotics.Tools to evaluate cognitive function in this study was PASAT test.

Results: The test results attention and concentration indicated that with worsening combined conditions Mean score of attention and working memory are reduced that these differences were statistically significant(pvalue<0.05). Mean scores working memory and attention in different condition Compared with the group exposed to non-harmful levels, was lower, in all conditions except Exposure to weak lighting statistically significant difference was shown(pvalue<0.007).

 Conclusion: combined exposure to harmful levels of noise, heat and lighting have adverse effects on cognitive performance parameters (attention and working memory) and Adverse effects increases with worsening conditions and exposure to three factors sound, heat and light their harmful levels.