How Pollution Affects Your Skin's Health

Air pollution has a range of harmful effects on the skin. The skin acts as a biological shield against pro-oxidative chemical and physical air pollutants, but prolonged or repetitive exposure to high levels of these pollutants may have profound negative effects. These effects include oxidative stress, inflammation, accelerated ageing, and a compromised skin barrier. The skin is exposed to a variety of environmental air pollutants, such as polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), oxides, particulate matter (PM), ozone (O3), and cigarette smoke. These pollutants can affect the structure and function of the skin, leading to inflammatory skin diseases, skin accessory diseases, immune-related skin diseases, and skin tumours. While the skin acts as a barrier, it is also one of the main targets of pollutants, which reach the superficial and deeper skin layers through direct transcutaneous uptake or indirect systemic distribution.

Skin ageing and inflammation

The human skin is exposed to various environmental factors, including air pollutants and ultraviolet (UV) light. Air pollution is a harmful environmental risk to human skin and can promote ageing and inflammation of the tissue. The main air pollutants that induce skin damage are particulate matter (PM) and gases such as ground-level ozone (O3).

Particulate matter, such as PM2.5 and PM10, are highly lipophilic and can penetrate the skin easily, leading to skin alterations such as impaired barrier function, pigment spots, wrinkles, and decreased skin hydration. A study showed that a one-unit increase in PMs was associated with a 20% increase in pigment spots on the forehead and cheeks and in wrinkles of the nasolabial fold.

Additionally, air pollution can induce inflammation by activating the AhR pathway and altering the skin microbiome. The link between low-grade systemic inflammation and biological ageing suggests that exposure to air pollution may lead to premature cellular senescence and, consequently, skin ageing.

Ultraviolet radiation (UVR) from the sun can also induce gene alterations or immunosuppression and increase the risk of skin cancer. The combination of UVR and exposure to PM and ozone has a synergistic effect, increasing oxidative stress and inflammation.

Overall, exposure to air pollution and UV light can lead to skin ageing and inflammation, with potential consequences including transepidermal water loss, lipid peroxidation, cell death, and degeneration of connective tissue.

Skin diseases

Air pollution has a range of harmful effects on the skin. It can cause oxidative stress, inflammation, accelerated ageing, and a compromised skin barrier. The skin is the target of several environmental stressors, and pollutants can penetrate the skin via direct transcutaneous uptake or via indirect systemic distribution of inhaled or ingested pollution through the blood.

The skin acts as a physical, chemical, and immunological barrier against environmental factors. However, when exposed to prolonged and repetitive environmental stressors, its barrier function can be disturbed, leading to the development of various skin diseases.

Atopic Dermatitis/Eczema: Toxic particles in the air can irritate and inflame skin affected by eczema, often exacerbating symptoms. Exposure to ozone and oxides has been associated with urticaria, eczema, and contact dermatitis.

Psoriasis: The inflammation caused by pollutants may worsen psoriasis symptoms, making it more challenging to manage.

Acne: City air, filled with pollutants, can clog pores and contribute to acne. The combination of pollutants and excess oil production can create an environment conducive to breakouts.

Skin Cancer: While UV exposure is a well-known risk factor for skin cancer, pollution can also play a role. Airborne pollutants can interact with UV radiation, potentially increasing the risk of skin cancer development. Polycyclic aromatic hydrocarbons, a type of air pollutant, are photoreactive and can be activated by UVR, enhancing their deleterious effects on the skin.

Lentigines: Commonly known as age spots or liver spots, these dark spots on the skin can be intensified by pollutants in the air.

Skin cancer

Skin is the largest organ in the human body and acts as a biological shield against pro-oxidative chemical and physical air pollutants. However, prolonged exposure to high levels of these pollutants may have detrimental effects on the skin.

Air pollution has been linked to inflammatory skin diseases, skin accessory diseases, immune-related skin diseases, and skin tumours. Skin cancer is among the most serious effects of air pollution on the skin. Polycyclic Aromatic Hydrocarbons (PAHs), which are common environmental pollutants, have been implicated in the development of skin cancer. PAHs are frequently bound to the surface of combustion-derived particulate matter (PM) and can be absorbed through the hair follicle or transepidermally. Long-term exposure to PM-bound PAHs can lead to oxidative stress and skin ageing, and ambient particles (such as soot) may be able to reach melanocytes and release surface-bound PAHs, thereby contributing to skin cancer.

In addition to PAHs, other air pollutants such as solar ultraviolet radiation (UVR), volatile organic compounds (VOCs), nitrogen oxides (NOx), ozone (O3), and cigarette smoke have been associated with skin cancer. Exposure to O3, for example, has been linked to eczema, contact dermatitis, and other nonspecific eruptions. Cigarette smoke, in combination with sun exposure, may also have a synergistic effect on skin ageing and an increased risk of skin cancer.

The impact of air pollution on skin cancer is particularly relevant in the context of climate change and rapid urbanisation, which have led to increased exposure to ambient air pollution. Higher temperatures result in people spending more time outdoors with less clothing, thereby increasing their exposure to UV light and other environmental dangers, like air pollution. Furthermore, burning fossil fuels in cars and power plants contributes to air pollution, and the pollutants can interact with heat and sunlight to form ozone, which can damage the skin and increase the risk of skin cancer.

To mitigate the impact of air pollution and climate change on skin health and skin cancer risk, experts recommend several strategies. These include staying out of the heat, wearing lightweight and sun-protective clothing, using mineral sunscreens containing zinc, titanium, or iron oxide, and wearing masks and sunglasses during acute air pollution events.

The impact of UV radiation

The sun releases ultraviolet (UV) radiation, which provides vitamin D to your body. However, too much UV exposure can have adverse effects on the skin. UV radiation is a "complete carcinogen", as it is a mutagen and a non-specific damaging agent, and has properties of both a tumour initiator and a promoter.

UV radiation is the primary cause of skin cancer, and excessive exposure to it carries profound health risks, including atrophy, pigmentary changes, wrinkling, and malignancy. The three most common types of skin cancer caused by UV radiation are basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. These cancers often appear on sun-exposed areas of the skin and are usually curable when detected and treated early. Cumulative sun exposure causes basal cell and squamous cell skin cancer, while severe blistering sunburns, usually before age 18, can cause melanoma later in life.

UV radiation damages the fibres in the skin called elastin, which causes the skin to sag, stretch, and lose its ability to return to its original position after stretching. The skin also bruises and tears more easily and takes longer to heal. UV radiation further damages the DNA in skin cells, causing genetic defects and mutations that can lead to skin cancer and premature ageing. It also increases the risk of developing melanoma, a dangerous type of skin cancer.

Additionally, UV radiation interacts with airborne pollutants, potentially increasing the risk of skin cancer development. Some polycyclic aromatic hydrocarbons are photoreactive and can be activated by UV radiation, enhancing their harmful effects on the skin. Therefore, it is essential to protect the skin from excessive UV exposure by taking protective measures, such as wearing sunscreen when outdoors.

Oxidative stress

Air pollution has a range of harmful effects on the skin. It can lead to various skin issues and can also weaken the skin's protective barrier, making it more vulnerable to allergens and irritants.

One of the key mechanisms by which air pollution damages the skin is through the generation of oxidative stress. Oxidative stress is an imbalance of free radicals and antioxidants in the body that leads to cell damage. Toxins like pollution and cigarette smoke can cause oxidative stress.

When it comes to the skin, oxidative stress is caused by a variety of factors, including solar ultraviolet, infrared and visible light, environmental pollution (including ozone and particulate matter), and psychological stress. These factors increase the production of reactive oxygen species (ROS) in the skin. ROS directly degrade biological macromolecules, including proteins, DNA, and lipids, which are essential for cell metabolism, survival, and genetics.

Additionally, environmental factors such as UV radiation and pollutants can impact skin microbiota compositions, leading to skin dysbiosis and various skin conditions.

The aryl hydrocarbon receptor (AhR) can act as a sensor for small molecules like air pollutants and plays a crucial role in responses to photo-pollution. Targeting AhR/Nrf2 is a novel treatment option for inflammatory skin diseases induced or exacerbated by air pollutants.

To combat the harmful effects of oxidative stress, certain foods that reduce free radicals in the body can be consumed. Antioxidants, such as vitamin C, resveratrol, and ferulic acid, can also be used to treat hyperpigmentation caused by oxidative stress.

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