To protect your skin from drying A/C and a lack of fresh air, focus on maintaining a strong skin barrier. This outer layer of skin helps lock in moisture and keep out irritants like bacteria. Think of it as a brick wall: skin cells are the bricks, held together by a mortar of fats and lipids — like ceramides — that keep skin soft and healthy. When that mortar weakens, moisture escapes, leading to dryness and sensitivity. Besides a gentle cleanser, Dr. Phillips recommends investing in a moisturizer containing either ceramides, niacinamide, or panthenol, all of which will seal in hydration and support the skin barrier.