IRCT20190515043594N1 IRCT 2019-10-28 Iran University of Medical Sciences Investigation the health effects of exposure to Trihalomethanes (THMs) in swimming pools Association between exposure to Trihalomethanes (THMs) in chlorinated and ozone/chlorinated swimming pools and metabolome-wide 2019-09-06 anticipated 58 Complete https://irct.ir/trial/39655 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Basic scienece, Randomization description: In order to random allocation of individuals in two groups, the permuted block randomization by using the web based software (www.sealedenvelope.com) will be applied. It should be noted that the length of blocks will be 4, Blinding description: All investigators of study outcomes (blood and alveolar air), will be unaware of the allocations. Also, when the statistical model of the primary and secondary results is not complete, the randomization code will not be broken. 3 The effects of chlorination and ozonation swimming pools (exposure to THMs) on metabolome profile levels. Intervention 1: Intervention group 1: Participants in the first group will be asked once to swim in chlorinated swimming pool for 40 minutes. Intervention 2: Intervention group 2: Participants in the second group will be asked once to swim in Ozone/ chlorinated swimming pool for 40 minutes. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is There is no more information.