Pollution's Impact: Skin Deep Troubles

Air pollution has a significant impact on the skin, with the skin acting as the body's first line of defence against environmental toxins. The skin is exposed to various air pollutants, including ultraviolet radiation, polycyclic aromatic hydrocarbons, volatile organic compounds, oxides, particulate matter, ozone, and cigarette smoke.

While the skin acts as a biological shield against pro-oxidative chemical and physical air pollutants, prolonged or repetitive exposure to high levels of these pollutants can have detrimental effects. These effects include premature skin ageing, skin cancer, atopic dermatitis, eczema, psoriasis, acne, and skin discolouration.

Additionally, pollution can cause skin irritation, rashes, and breakouts, particularly during peaks in pollution. This is due to dirt particles accumulating on the skin's surface, clogging pores when mixed with skin cells and oils.

To counteract the effects of pollution, it is recommended to maintain a healthy skin barrier function and cleanse the skin regularly to block pollutants from invading the skin. Antioxidants, both topical and ingestible, can also help prevent the free radical damage caused by pollution.

Oxidative stress and skin ageing

Oxidative stress is a major contributing factor to the ageing process. It is caused by an imbalance in the production of free radicals, which can be induced by exposure to environmental stressors such as ultraviolet radiation and air pollution.

Oxidative stress is caused by an imbalance in the production of free radicals, which can be induced by exposure to environmental stressors such as ultraviolet radiation and air pollution.

The Role of Mitochondria

Mitochondria are the major source of cellular oxidative stress and are widely implicated in cutaneous ageing. They are highly vulnerable to oxidative damage due to their proximity to the site of ROS production and limited DNA repair mechanisms. This can lead to a vicious cycle where dysfunctional mitochondria contribute to further ROS production, resulting in further oxidative damage.

Environmental Sources of Oxidative Stress

Ultraviolet Radiation

Ultraviolet radiation (UVR) is the primary environmental factor in the development of extrinsic skin ageing. Exposure to UVR stimulates the production of reactive oxygen species (ROS) and generates oxidative stress. UVR can also directly damage DNA, leading to mutations.

Environmental Pollution

Air pollution is an increasingly significant global concern and has been linked to the development of the signs of extrinsic skin ageing. Ambient pollutants such as particulate matter and nitrogen dioxide have been associated with pigment spots and wrinkles.

Mechanistic Evidence

Experimental studies have provided mechanistic explanations for the epidemiological associations between air pollution and skin ageing, focusing on the generation of reactive oxygen species (ROS) and cellular stress through recognised signalling pathways.

Ground-Level Ozone

Ground-level ozone is a highly reactive environmental pollutant capable of inducing oxidative stress in cutaneous tissues. It reacts with antioxidants, unsaturated fatty acids and lipids in the stratum corneum, leading to the generation of cytotoxic molecules. This can result in a cascade of cellular stress responses in the deeper, viable layers of the skin.

Particulate Matter

Particulate matter has been shown to induce oxidative stress and cellular damage in human clinical, animal and in vitro systems. It can generate ROS and activate redox-sensitive transcription factors within cell nuclei.

Strategies for Protection

Strategies for protection against the effects of air pollution on skin ageing may include the use of antioxidants, both topical and dietary, as well as measures to reduce exposure to pollutants.

Synergy with Sunlight

There is evidence that environmental factors such as ultraviolet radiation and air pollution may have additive or synergistic effects on the skin. For example, polycyclic aromatic hydrocarbons, a component of particulate matter, are highly photo-reactive and can induce oxidative stress under UV exposure.

Oxidative stress induced by reactive oxygen species plays a major role in the process of skin ageing. Exposure to environmental stressors such as ultraviolet radiation and air pollution can generate oxidative stress, leading to the phenotypic features of extrinsic skin ageing.

Irritation and inflammation

Air pollution can cause skin irritation and inflammation, which can lead to various skin problems. The skin acts as a natural barrier against external factors, but it is not completely impenetrable.

The impact of pollution on the skin

Small nanoparticles in the form of dirt, dust, or soot can enter and negatively impact skin cells, causing premature ageing in a process called oxidation. Gases such as nitrogen dioxide, ozone, carbon monoxide, and sulfur dioxide can also harm the skin.

How pollution affects the skin

Pollution hurts the skin's barrier function by breaking down collagen and the lipids contained within it. Studies have shown that women who live in urban areas have skin that is up to 10% older than those who don't. Additionally, pollution can cause irritation, rashes, and breakouts, particularly during peaks in pollution.

The impact of pollution on skin conditions

There is a clear correlation between spikes in air pollution and increases in the number of people suffering from skin problems such as acne, hives, and eczema. It is clear that air pollution is not just affecting the skin on a cosmetic level but also poses a real threat to skin health.

The impact of pollution on skin hydration and barrier function

Those living in highly polluted areas have significantly worse skin hydration than those living in cleaner suburbs, despite making better lifestyle choices. In addition, compromised skin barrier function has been found in urban dwellers.

The impact of pollution on skin ageing

Pollution is associated with signs of ageing in exposed skin. A study found a link between exposure to higher levels of airborne pollution and increased numbers of lentigines (age-associated pigment spots) on the forehead and cheeks, as well as increased nasolabial fold wrinkles.

The impact of pollution on inflammatory skin diseases

The symptoms of chronic inflammatory skin diseases seem to be exacerbated when adult and paediatric subjects are exposed to high pollution levels.

Allergic skin conditions

Air pollution can induce inflammatory skin diseases, skin accessory diseases, immune-related skin diseases, and skin tumours. The skin is the largest organ and the first barrier that protects us from the outside world. Air pollutants such as particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), nitrogen oxides (NOx), and cigarette smoke will affect the structure and function of the skin and bring about the development of inflammatory skin diseases (atopic dermatitis, eczema, psoriasis, acne), skin accessory diseases (alopecia), auto-immune skin diseases (cutaneous lupus erythematosus, scleroderma), and even skin tumours (melanoma, basal cell carcinoma, squamous-cell carcinoma).

Oxidative stress, skin barrier damage, microbiome dysbiosis, and skin inflammation are the pathogenesis of air pollution stimulation.

The skin may be affected by environmental pollutants concentrating at its surface. Airborne pollutants can penetrate the skin via direct transcutaneous uptake or via indirect systemic distribution of inhaled or ingested pollution through the blood.

Pollutants may activate cell metabolism and inflammatory processes. Activation of the AHR pathway has also been implicated in the pathology of atopic dermatitis in humans. Activation of the AHR pathway in NHEKs by PM or B [a]P has been linked to the induction of proinflammatory molecules, such as interleukin-8 and cyclooxygenase-2 via the production of reactive oxygen species (ROS) involved in oxidative stress processes.

A reduction in vitamin C and E levels after exposure to O3 was first identified in the upper epidermis of mouse skin. Similar findings were reported in humans when forearm stratum corneum was experimentally exposed to environmental O3 levels. A 10-fold increase in lipid peroxidation was also observed in the mouse epidermis after exposure to O3. In humans, higher levels of oxidization of squalene, a human sebum-specific unsaturated fatty acid, have been reported in sebum experimentally exposed to cigarette smoke.

In vitro and in vivo skin changes in oxidation status after exposure to pollutants have been observed in studies. Clinical evidence for an oxidative stress response occurring in humans after exposure to pollutants comes from two prospective clinical studies comparing the impact of pollution on subjects living in Mexico City and Cuernavaca, or in urban and rural areas of Shanghai. Among several biochemical changes in sebum and the stratum corneum, vitamin E, squalene and ATP levels decreased. In contrast, oxidized protein levels were augmented, indicating that skin antioxidant molecules were depleted in subjects exposed to elevated pollution levels.

Moreover, in vitro experiments showed that the induction of cytotoxic and oxidative mechanisms by some PAHs was increased when human keratinocytes were exposed to both PAHs and UVA in particular. In mouse skin, UVA exposure significantly increased the toxic impact of B [a]P or cigarette smoke, including the induction of squamous cell carcinoma. In humans, more smokers exposed to sunlight present facial wrinkles than either smoking or sun-exposed subjects alone. An increase in elastosis was found in the sun-exposed skin of the forehead and cheeks of smokers vs non-smokers.

Living in a polluted environment may also reduce skin moisture, increase the rate of sebum excretion and likely exacerbates the symptoms of chronic inflammatory skin diseases both in children and adults.

Skin cancer

The Impact of Air Pollution on Skin Cancer

The skin is a target organ for pollution, and air pollutants can have detrimental effects on skin health. Air pollution includes a mixture of tiny particles and substances in the air, such as fumes from vehicles, factories, and smoke from burning fuels. These pollutants can be absorbed through the skin and lead to negative health outcomes.

Mechanisms of Action

One way air pollution may contribute to skin cancer is by damaging DNA in skin cells. The tiny particles in air pollution can build up in the lungs and cause genetic mutations, leading to uncontrolled cell growth and the formation of tumours. Additionally, air pollution can cause physical damage to skin cells, leading to inflammation and oxidative stress, which are known risk factors for cancer.

Studies on Air Pollution and Skin Cancer

A study by Goldsmith in 1996 highlighted the link between air pollution and skin cancer. The study found that for every 1% decrease in ozone levels, there was a corresponding 2% increase in UVB irradiance, resulting in a predicted 2% increase in skin cancer cases. This is particularly concerning for dermatologists as UVB irradiation is closely associated with skin cancers.

Another study by Puri et al. in 2017 also emphasised the impact of air pollution on skin health and diseases, including skin cancer. The study suggested that air pollutants could be absorbed through the skin, leading to biochemical changes and molecular mechanisms that promote cancer development.

Reducing the Risk of Skin Cancer from Air Pollution

While air pollution is a significant risk factor for skin cancer, there are ways to mitigate its impact:

• Using indoor air filtration systems and regularly changing filters can help reduce exposure to air pollutants.
• Avoiding high-traffic areas and sources of diesel exhaust can lower your exposure to harmful pollutants.
• Walking, cycling, or wheeling instead of driving can also help reduce emissions and your exposure to air pollution.

In conclusion, while air pollution is a concern for skin cancer, further research is needed to fully understand the complex relationship between pollution and skin health. Protecting the skin from pollution and taking preventative measures can help reduce the risk of skin cancer and other skin diseases.

Skin barrier function

The skin acts as a natural barrier against external factors, but it is not completely impenetrable. Pollution hurts the skin's barrier function by breaking down collagen and the lipids contained within it.

Oxidation caused by pollution can make skin age prematurely. Studies have shown that women who live in urban areas have skin that is up to 10% older than those who don't.

The skin's barrier function can be compromised by pollution, which can also draw out moisture from the skin, making it look duller in appearance.

To strengthen the skin's barrier function, it is important to use a moisturiser at night.

Additionally, pollution can cause irritation, rashes and breakouts, particularly during peaks in pollution. Dirt particles can accumulate on the skin's surface, clogging pores when they mix with skin cells and oils.

Cleansing is key to fighting the effects of pollution on the skin. It is recommended to cleanse twice a day with products formulated with antioxidants.

Antioxidants are molecules that can neutralise free radicals, thus mitigating their negative effects.

A strong skin barrier is key to fighting off pollution.

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