In response to the following comment: “Pollution levels are high in cities and clear, blue skies have become rare. I think the haze blocks a lot of the sun.”
This study compared vitamin D status in 200, free-living, woman, aged between 20 to 55 years, from Tehran, a high-polluted area, and Ghazvin, a low-polluted area. Level of UVB (ultra-violet B – the part of the light spectrum the skin uses to make vitamin D) was measured; less UVB means more haze or more pollution. The average blood vitamin D levels were significantly higher in women from the low pollution area and was related to the degree of haze or pollution over these cities.