BACKGROUND: The Physiological Equivalent Temperature (PET) index providing a standardized reference point, PET enables non-experts to better understand and assess the physiological implications of varying environmental temperatures and thermal comfort levels across different settings. We aimed to evaluate the relationships between the PET Index and Hospitalized due to Respiratory Diseases (RD) and Cardiovascular Diseases (CVD) in Dezful city. METHOD: Hospital admissions, climate variables and environmental pollution data (PM RESULT: In high PET, the risk of respiratory diseases has been significantly reduced (Lag DISCUSSION: It seems that in Dezful, low levels of PET increase the risk of hospitalization for cardiovascular patients, while due to certain factors, including the potential adaptive effect of the people of Dezful to heat on health, high levels of PET reduce the risk of hospitalization for all respiratory diseases and the risk of cardiovascular hospitalization in women.