Interview/ Dr Vandana Yadav, assistant professor, department of dermatology and venereology, Hind Institute of Medical Sciences, Lucknow
How does air pollution impact the skin?
Air pollutants can exist as solids, liquids, gases and particulate matter. These are absorbed directly through the skin into the subcutaneous tissue or via hair follicles and sweat/sebaceous glands. The skin, being the largest and outermost body organ, acts as a physical, chemical and immunological barrier against environmental factors. Whenever prolonged and repetitive exposure to environmental stressors exceeds the skin’s normal defensive potential, there is a disturbance in the skin barrier function, leading to the development of various skin diseases.
What pollutants impact the skin the most?
Exposure to ultraviolet radiation has been associated with extrinsic skin ageing and skin cancers. Cigarette smoke contributes to premature ageing and an increase in the incidence of psoriasis (which exhibits as scaly, inflamed skin), acne and skin cancers. It also causes allergic skin conditions such as atopic dermatitis and eczema (both display dry, itchy, inflamed skin). Polycyclic aromatic hydrocarbons (from the burning of coal, oil, gas, wood, garbage) are associated with extrinsic skin ageing, pigmentation, cancers and acneiform eruptions (manifest as small, raised, acne-like bumps on the face, scalp, chest and upper back).
Volatile organic compounds (human-made chemicals used and produced in the manufacture of paints, pharmaceuticals and refrigeration) have been associated with atopic dermatitis.
What is the mechanism for manifestation of these skin issues?
Air pollutants exert a harmful effect on the skin by increasing oxidative stress, which depletes the skin's antioxidant defence. (Antioxidants are manmade or natural substances that may prevent or delay some types of cell damage.) Free radicals and reactive oxygen species (an umbrella term for highly reactive chemicals) are generated that interact with the cell membranes and damage them. Reactive oxygen species also stimulate the release of other pro-inflammatory mediators, which results in the accumulation of neutrophils (a kind of white blood cells that are the body’s first line of defence) and other phagocytic (immune) cells that further generate free radicals, thereby resulting in a vicious cycle. Oxidative stress initiates complex biological processes resulting in genetic damage and other processes involved in cell growth and differentiation and in the degradation of the connective tissue of the dermis. Air pollutants induce severe alterations of the normal functions of lipids, DNA and/or proteins in the human skin via oxidative damage, leading to extrinsic skin ageing, inflammatory or allergic conditions such as contact dermatitis, atopic dermatitis, psoriasis, acne and skin cancer.
Is there a gender differential?
The different impacts on genders were mainly because of the difference in the level of exposure as more males did outdoor work. However as work culture changes, females and males appear to be at the same risk.
What are some protective strategies?
Strategies for personal protection against increasing air pollution include physical photoprotection by use of sunscreens; avoidance of areas with public smoking and around industries; usage of topical (applied to the body’s surface) antioxidants such as vitamin C and E in formulations along with sunscreen; and use of indoor air purifiers and ventilators. People with high occupational risk, such as traffic police and cleaning staff, should use masks while at work.