The outermost layer of the skin often serves as a physical barrier against harmful environmental toxins, as it is directly exposed to various pollutants such as particulate matter and free radicals. As its immediate proximity to external environment puts the skin at greater risk of being damaged by stressors, it is important that we take extra care in avoiding such environmental hazards as much as we can.
Oxidative Stress in Skin
Our skin is often exposed to a variety of harmful electrophiles and free radicals, often produced as a result of exposure to chemicals and ionizing radiation. Our body naturally produces reactive oxygen species (ROS) as byproducts of cellular processes, but an excess of ROS causes oxidative stress in skin cells.
According to Dr Teo Wan Lin, an accredited dermatologist at TWL Specialist Skin and Laser Centre, she said: “Our body keeps levels of ROS in check with free-radical-scavenging mechanisms, such as antioxidants. External sources of ROS, such as UV radiation, environmental pollutants and harmful chemicals, can cause a state of oxidative stress when they overwhelm our body’s defences and become unable to keep up with the frequent ROS production. It is the excessive generation of ROS that we should avoid for healthier skin.”
Oxidative stress causes our cellular components and macromolecules such as DNA, RNA, protein or lipids to be damaged. When ROS reacts with the lipid bilayer of our skin, it can lead to a weakened skin barrier function.
Environmental air pollution consists of various particulate matter (PM). PM includes harmful suspended contaminants in the air and is heavy contributors to air pollution. We are familiar with PM 2.5, which can be found from diesel-exhaust particles that are less than 2.5μm in diameter. Composed of organic carbon compounds, nitrates and sulfates, PM2.5 can settle on the skin and aggravates inflammatory response in our skin cells, triggering skin symptoms.
The main mechanism of PM2.5 is the generation of ROS, leading to greater oxidative stress on skin cells. These particles can act as carriers for unwanted chemicals and metals that can localise in our mitochondria. This leads to the production of ROS in the mitochondria, and causing the effect of collagen degradation in our skin and thereby result in wrinkle formation and skin ageing.
On the surface of PM are polycyclic aromatic hydrocarbons that can lead to not only an increased production of ROS, but also interfere with our gene expression for wrinkle formation and pigment spot formulation.
Our skin condition is also affected by ultraviolet (UV) radiation. The solar UV spectrum is divided into two specific wavebands according to wavelength: UVA and UVB. Excessive sun exposure initiates photo-oxidation reactions, causing damage to our skin cells as it affects pathological processes.
Radiation from UVA penetrates into the deeper layers of our skin, inducing the production of ROS and causing extensive damage. Sunburns are caused by UVB, as an inflammatory response from our skin due to photodamage. UVB can also cause mutation and skin cancer.
An exposure to UV radiation is the main factor of skin aging, known as photoageing. The rate of degeneration depends on the frequency, duration and intensity of our cumulative exposure to solar rays and the degree of protection of our skin pigmentation. Given that photoaging accounts for as much as 80 per cent of facial aging, we should always be armed with sun protection.
There are various ways to protect your skin against environmental aggressors. A good supply of anti-oxidants in your diet can provide photoprotection against solar UV radiation. Carotenoids, vitamin E and C are good anti-oxidants.
Any prevention must be complemented with the use of topical sunscreen with a high sun protection factor. Not all sunscreens are created equal. Dermatologists would recommend only a few brands of sunscreens. Effective sunscreens will protect against skin cancer and block out harmful UVB rays. Ingredients that a good sunscreen should include are derivatives of vitamin C, antioxidants or phytochemicals.
Those blessed with normal skin conditions should continue regular application of sunscreen, and stick to gentle skincare products. Patients with eczema are advised to visit a dermatologist if their condition continues to worsen from environment aggressors. Topical steroids and emollients may be prescribed, as eczema is not a condition that will go away in time.
Lifestyle habits such as smoking and drinking as it can increase the production of free radicals and accelerate skin aging. For those at high-risk with excessive exposure to sun, sun avoidance is advocated whenever possible. Avoid the sun from 10am to 4pm, and don on long sleeves for greatest protection.
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Meet with Dr. Teo Wan Lin, an accredited dermatologist at TWL Specialist Skin & Laser Centre, for a thorough consultation to determine the most suitable treatment for your skin.
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Tags: PM, Sunscreen