Dry skin has less NMF and environmental factors such as sun exposure and low-humidity air decrease levels of NMF in every type of skin. (If you???ve ever wondered why skin gets dry and peels after a sunburn, it???s because UV exposure lowers NMF levels.) Our skin compensates for arid air by producing more NMF, but it can take time (at least 3 days) for cells to ramp up and produce more.