The impact of air pollutants, UV exposure and geographic location on vitamin D deficiency.

Vitamin D (VD) is an important nutrient for preventing several chronic diseases, and vitamin D deficiency (VDD) causes many diseases. Air pollution has been reported as one of the most significant factors that causes VDD. Some epidemiological studies have evaluated VDD prevalence, and presented air pollution as a potential cause of VDD. In addition, recent case studies have found that VDD is associated with air pollutants. Nearly all reports agree that air pollution affects VD levels by reducing sun exposure, especially UVB radiation. Sun exposure accounts for >90% of VD production in humans. Recent studies have demonstrated that tropospheric ozone and particulate matter are independent risks to VD levels and cause deficiency. However, obtaining comprehensive conclusions on the impact of air pollution on VDD is necessary. This study aims to review all related papers to determine how air pollution can affect VD levels.