Cold Air
When it gets cold, exposed skin tends to get dry. It becomes itchy and uncomfortable, and it can crack and become damaged.
The main reason is that cold air can not contain as much moisture as warm air. As soon as cold air is warmed, by contact with the skin for example, the relative humidity of the air goes down, and the air becomes dry. The same thing happens with central heating. Cold air is warmed by the radiators, and this reduces the relative humidity, so the air becomes dry. Dry air will absorb moisture from anywhere it can, including from the surface of any exposed skin, and this is why the skin becomes dry.
When the skin is too dry, it can't function as well. Healthy skin needs a constant supply of oxygen and nutrients, and it needs to rid itself of toxins. None of these processes can work properly if there is not enough moisture in the skin.
The problem is worse when the skin is cold. The body tries to minimise heat loss by closing down blood vessels near the surface . This restricts the supply of moisture and nutrients, so the skin is not replenished.
It is difficult to put moisture back into the skin directly. One function of the skin is to act as a waterproof outer layer, and the oils in the skin repel moisture if it is in liquid form. If you take a long soak in the bath, the skin of the hands and feet does go wrinkly, it is true, but this effect is caused by the keratin in the dead outer layers absorbing water. The keratin layer expands and it is this expansion that causes the wrinkles. Particularly if a chemical soap or detergent is used, natural oils are removed from skin, and the moisture absorbed by the keratin soon evaporates, leaving the skin drier than before.
There are three main strategies for avoiding the problems associated with dry skin - avoidance, nutrition, and replacement.
Avoidance
Not always possible, one way of avoiding dry skin is to avoid exposing the skin to conditions that may cause it. This means wearing gloves to protect the hands on cold dry days, and protecting the face with a hood or scarf.
Nutrition
If the body is well nourished, and the circulatory system is working well, then any moisture losses from the surface of the skin can be more easily replaced. It is important to maintain fluid intake in cold dry weather, and also to make sure that the diet contains the full range of omega-3, -6,and -9 oils. Many modern dies are deficient in omega-3 oils, which can be obtained from oily fish and olive oil. They help to keep the skin hydrated and to reduce the rate at which water evaporates from the surface.
Replacement
As we have seen, it is very difficult to replace moisture by applying it as a liquid. A steamy shower works somewhat better than a bath as the water vapour in the steam permeates into the skin more easily without stripping out the natural oils in the way that a bath does. Better still is to apply moisture to the skin in a way that is more easily absorbed, and to do this it needs to be emulsified with oil. This is what good creams and lotions are - emulsions of oil and water. The skin is much more permeable to an oil and water emulsion than water or water vapour alone, and research shows that the presence of sesquiterpenes, key parts of essential oils, can increase the permeability of the skin by a factor of 50. The oil/water emulsion carries into the skin any other ingredients in the cream, and provides another route for nutrients to enter the body.
The Problem with Petroleum
Many people use Vaseline and similar products to prevent the skin drying out. Petroleum jelly, of which Vaseline is one brand, was developed by the oil drilling industry to lubricate drill shafts cutting through rock. The workers started applying it to their skins, and found that it stopped their skins drying out. Unfortunately, that's all it does. It seals the surface of the skin, and stops it breathing. The body soon becomes dependent on the layer of Vaseline to seal in moisture, and becomes dryer as soon as the Vaseline is removed. It's much better to use a product that is absorbed into the skin and supports the skin's own natural function, than one that suffocates it.
