Sunlight plays an important role in vitamin D production, however, there are other factors that may contribute to vitamin D deficiency regardless of getting enough sunlight. In areas with poor air quality, carbon particles scatter and absorb UVB which lessens vitamin D production. Fat is known to readily take up vitamin D, hence higher body weight may affect the bioavailability of vitamin D. Melanin competes with the substance in the skin that kickstarts vitamin D production for UVB making individuals with more melanated skin require more vitamin D. Lastly, as we get older, we have lower levels of the substance in the skin that UVB light converts into the vitamin D precursor, so it may be beneficial to supplement.