What is the exposome and how does it affect skin ageing?

Learn what the exposome is, how it can influence skin ageing and which measures may help protect the skin from its effects.

The term exposome, coined by Christopher P. Wild, refers to the totality of environmental and lifestyle exposures that can influence health throughout life, beyond genetic factors.

Although the relationship between the exposome and disease has been studied in many scientific fields, dermatology is one of the areas in which the concept has been explored in particular depth. External exposures may affect skin health through several mechanisms, including:

• Alteration of the skin barrier, including the hydrolipidic film that helps protect the epidermis and limit water loss.

• Increased oxidative stress and formation of reactive oxygen species.

• Changes in cellular repair and tissue remodelling, including processes involving collagen and elastin.

Exposome factors involved in skin ageing

Several exposome-related factors have been associated with skin ageing. These commonly include solar radiation, smoking, air pollution, diet, stress, sleep and climate.

Some act directly on the skin, while others may influence it indirectly through their effects on general health, inflammation or oxidative stress.

Not all of these factors can be avoided completely, but exposure can often be reduced and protective measures adopted.

1. Solar radiation

There is extensive evidence linking ultraviolet radiation, particularly UVA and UVB, with oxidative stress and a wide range of biological effects. Excessive ultraviolet exposure can contribute to sunburn, immune changes and several skin diseases.

From a dermatological perspective, one of the most important consequences is skin cancer. Ultraviolet radiation is a major environmental risk factor for several forms of skin cancer, including melanoma.

Sun exposure also plays a central role in photoageing. Repeated unprotected exposure contributes to pigmentation changes, dark spots, uneven skin tone, wrinkles, changes in texture and loss of firmness.

For this reason, sun protection should form part of skin care from childhood onwards. The effects of solar radiation are cumulative, and visible changes may become apparent only after years of exposure. In addition to ultraviolet radiation, visible light and infrared radiation have also been studied for their potential contribution to certain aspects of skin ageing, although their biological effects differ from those of UV radiation.

2. Smoking

Smoking is one of the most important avoidable environmental factors associated with premature skin ageing. Smoking increases oxidative stress and exposes tissues to numerous toxic substances that may affect DNA, vascular function and cellular repair mechanisms. Tobacco smoke is also associated with several cancers and may influence inflammatory skin conditions.

Smoking has been linked to changes in skin colour, texture and elasticity, as well as more pronounced facial wrinkling, particularly around the mouth. Its vasoconstrictive and vascular effects may also impair tissue oxygenation and wound healing.

3. Air pollution

The relationship between air pollution and skin health has received increasing scientific attention. Pollutants such as particulate matter and polycyclic aromatic hydrocarbons have been associated with oxidative stress, inflammation and changes in skin pigmentation and ageing. Research also suggests that environmental pollution and ultraviolet radiation may interact, potentially increasing oxidative damage in exposed skin. This combined effect is sometimes referred to as photopollution. The magnitude of the effect varies according to the type and level of pollution, individual susceptibility and other environmental exposures.

4. Diet

Diet is another component of the exposome that may influence skin health. A varied and balanced diet contributes to general health and provides proteins, vitamins, minerals and other nutrients required for normal skin function.

Fruit and vegetables are important sources of antioxidants and other bioactive compounds, while adequate protein intake contributes to normal tissue maintenance. Rather than focusing on individual foods as a way of preventing skin ageing, the most appropriate approach is to follow an overall healthy dietary pattern. Limiting excessive alcohol consumption and reducing the intake of highly processed foods, refined sugars and excessive saturated fat can also form part of broader health recommendations.

5. Stress

Psychological stress can influence several dermatological conditions and may contribute to flare-ups in susceptible individuals. Conditions such as acne, rosacea, psoriasis and atopic dermatitis may be affected by stress in some patients. Stress activates neuroendocrine and inflammatory pathways, including changes involving cortisol. These mechanisms can influence skin barrier function, inflammation and oxidative stress. However, the relationship between stress and skin ageing is complex and depends on many interacting biological and behavioural factors.

6. Lack of sleep

Sleep is involved in numerous physiological repair and regulatory processes. Insufficient or poor-quality sleep has been associated with changes in skin barrier recovery, stress responses and perceived signs of ageing.

People who regularly sleep poorly may notice changes such as dullness, increased sensitivity, dehydration or more noticeable under-eye changes. Persistent sleep disturbance can also affect general health, which in turn may influence the condition of the skin. Although individual sleep requirements vary, maintaining adequate and regular sleep is an important part of general health.

7. Climate

Environmental temperature and humidity also influence the skin. High temperatures can increase sweating and may contribute to inflammation, vasodilation and changes in skin barrier function. Heat-induced biological changes have also been studied in relation to so-called thermal ageing, although the clinical importance of this mechanism varies according to exposure.

Cold weather can reduce skin hydration and compromise the skin barrier, particularly when accompanied by low humidity, wind and indoor heating. When the barrier is impaired, the skin loses water more easily and may become dry, tight, itchy or irritated. People with conditions such as eczema may be particularly sensitive to these changes. Adapting skincare to the climate — for example, by using appropriate moisturisers and protecting the skin from excessive environmental exposure — can help support normal barrier function.

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