Air pollutants are negatively associated with vitamin D-synthesizing UVB radiation intensity on the ground

Atmospheric levels of pollutants may reduce the UVB intensity at the earth's surface, with a subsequent reduction in cutaneous vitamin D synthesis. We investigated the association of various pollutants with UVB intensity on the ground. Four-year data obtained from four weather stations from across Kuwait were analyzed by median regression. Pollutants that were negatively associated with UVB were [β (95% CI)]: benzene [- 2.61 (- 4.13, - 1.09)], ethyl-benzene [- 2.20 (- 3.15, - 1.25)], ozone [- 0.23 (- 0.28, - 0.17)], nitric oxide [- 0.11 (- 0.15, - 0.06)], sulfur dioxide [- 0.10 (- 0.17, - 0.04)] and particulate matter PM₁₀ [- 0.002 (- 0.003, - 0.002)]. Pollutants that were negatively associated with the UVB/UVA ratio were [β (95% CI)]: benzene [- 15.57 (- 24.94, - 6.20)], nitric oxide [- 0.53 (- 0.81, - 0.25)], ozone [- 0.38 (- 0.70, - 0.06)], and total hydrocarbon [- 0.02 (- 0.04, - 0.01)]. Furthermore, benzene and nitric oxide levels were higher in the morning and evening hours, which are the times of most solar exposure in this region due to high temperature during midday. In addition to other known factors, attenuation of UVB by these pollutants may contribute to lower vitamin D levels in populations. In addition to direct public health hazard, these pollutants may contribute to the very high prevalence of VDD in this region.