Investigating the relationship between the long-term exposure to air pollution and the frequency of depression in Shiraz during 2010-2017

Background: Exposure to environmental pollutants which have entered the atmosphere due to human and industrial activities results in harmful and unwanted effects on human health. The undesired effects of air pollution on mental disorders, mortality, and psychological disorders have been proven. Depression is a common mental health problem in today's societies which impacts the quality of life. The objective of this study was to determine the relation between exposure to air pollution and frequency of depression in Shiraz (Southern Iran). Methods: Archived documents of 2658 patients diagnosed with major depressive disorder (MDD) from a psychiatric university hospital were reviewed. The concentrations of five air pollutants including CO, NO X, O3, PM10, and NO2 were determined daily in two air quality monitory stations in downtown Shiraz (Imam Hossein Square) and Kazeroon Gate. The data relevant to these five pollutants were gathered every day for 83 months, from 2010 to 2017, and for more precision, the mean values were used. The relationship between the concentration of each pollutant in the air and the number of patients referring to hospital was determined using the Spearman's correlation coefficient. Results: There was a direct and significant relationship between all pollutants and the number of hospital admissions in each month (P < 0.05) except for CO which did not show a significant relationship with hospital admission due to depression (P > 0.05). Conclusion: The results of this study indicated a positive relationship between air pollution and depression. Of course, to prove this relationship, it is essential to conduct a number of studies with appropriate methodology and design