Ultraviolet Rays: UVA vs UVB vs UVC
UVA vs UVB vs UVC – what are the differences in these ultraviolet (uv) rays? Firstly, we need to understand that the sun not only produces visible light but also energy and UV radiation. Together, they travel as a spectrum of waves in the form of electromagnetic radiation through the sun’s layers. They then reach the surface of the sun before propagating through space and ultimately reaching the Earth’s atmosphere.
While the ozone layer is able to absorb the ultraviolet radiation from the UVC rays, UVA and UVB radiation unfortunately can penetrate through and cause harm to our skin. This is because UVA and UVB rays have longer wavelengths and lower energy compared to UVC rays.
UVA vs UVB Radiation: What Are Their Differences?
Comparing UVA vs UVB radiation is like weighing up the lesser or more of two evils. Let’s just say that without either of them, skin-aging would be slower, and the risk of skin cancer, significantly slower. Nevertheless, should a side-by-side analysis be necessary, here are some key differences.
UVA (Ultraviolet-A) Radiation: The Ticking Time Bomb
UVA rays, with the longest wavelength and the lowest energy, get least filtered by the ozone layer. However, of all the three ultraviolet rays, UVA penetrates the deepest into the dermis. Dermis is the middle layer of the skin between the epidermis (outermost layer) and the hypodermis (innermost layer). UVA rays make up 95% of the radiation in our atmosphere and are known as “aging rays”. UVA radiation causes long-term sun damages such as premature aging (photoaging) and even skin cancers.
Premature Aging and Photoaging
The dermis is also the skin’s connective tissue layer. It contains the collagen and elastin fibres that strengthen the skin’s structure while allowing it to still be supple. Thus, exposing our skin to UVA rays for a prolonged period causes collagen and elastin to break down. The skin loses not only resilience but also elasticity and firmness. UVA exposure results in advanced photoaging including wrinkles, fine lines and age spots, etc, being formed. This thickens the epidermis, causing the skin to have a leathery texture and uneven skin tone. Freckles and dark spots may advance to hyperpigmentation as they get deeper rooted due to overstimulation of melanin production.
UVA Skin Cancer
Sun damages from UVA radiation can indirectly cause skin cancer. Although UVA rays are less likely to cause skin cancer compared to UVB rays, they are still capable of damaging DNA, causing skin cell mutations that may eventually give rise to cancerous growth.
UVA Tanning
Tanning beds use ultraviolet (UV) A radiation significantly more intense as opposed to the UVA present in natural sun tanning. The process involves speeding up melanocytes into producing melanin to give the skin its darker pigment. The ultraviolet (UV) A radiation used in tanning beds or solariums has been associated with the development of squamous cell carcinoma.
UVB (Ultraviolet-B) Radiation: The Imminent Danger
Ultraviolet (UV) B rays possess higher energy and shorter wavelength than UVA rays and therefore, have a higher biological potency on the skin. While UVB rays account for merely 5% of the earth’s ultraviolet radiation, they pose more significant danger to the skin compared to UVA rays. They are easier to be absorbed by the skin’s outer layer (epidermis), and can directly damage the DNA in skin cells.
Photoaging and Skin Repair Impairment
Overexposure to UV radiation, particularly UVB rays, create free radicals and induce oxidative stress in the skin. Like UVA rays, they accelerate skin aging by hindering the skin’s natural ability to regenerate itself. UVB radiation affects skin cell functions, suppressing the immune system and can lead to chronic low-grade inflammation, contributing to rapid photoaging. It also interferes with normal skin cell growth and its natural defence mechanisms, such as melanin production. Visible signs of photoaging include sagging skin, rough skin textures, wrinkles, fine lines, and the formation of sunspots and uneven pigmentation, etc.
Sunburns and Inflammation
Ultraviolet (UV) B radiation is the main cause of sunburns and inflammation of the skin. Our skin’s outer layer, the epidermis, is composed of cells (keratinocytes) that would interact with UVB radiation. Long exposures to UVB rays interfere with such interactions and disrupts the DNA structure of the epidermis. In first-degree sunburns, the outer layer of the skin experiences redness, burning pain and swelling.With prolonged UVB sunlight exposure, second-degree sunburns can damage the skin’s nerve endings as deeper skin layers such as the dermis get affected.
UVB rays cause skin cellular damage, and these damaged cells in turn release inflammatory chemicals in the skin. Fluid may then accumulate in the damaged tissue, and redness, warmth and swelling occur as a result of these biological inflammatory responses. In severe cases, the skin may blister and become infected.
UVB Skin Cancer
Ultraviolet (UV) B rays increase the chances of getting skin cancer like melanoma, the deadliest form of skin cancer. Other types of skin cancer caused by UVB radiation are Basal Cell Carcinoma (BCC) and Squamous Cell Carcinoma (SCC).
Basal cell carcinoma is the most common type of UVB-related skin cancer and affect mostly skin areas exposed to the sun. It develops at a slower rate, and affects areas like the neck, face and scalp.
Like UVA radiation, UVB sunlight exposure can also bring about Squamous Cell Carcinoma. This type of cancer spreads most aggressively. Squamous cell carcinoma can grow on other parts of the body if not immediately surgically removed.
Melanoma is the most dangerous type of skin cancer. It metastasizes rapidly and can multiply from localised abnormal cells, invading surrounding tissues. Melanoma cells are highly invasive and can enter the bloodstream or lymphatic system. These melanoma can cells then spread to the lymph nodes, organs and even bones.
UVC Ultraviolet Light Rays
UVC radiation is the deadliest amongst the three uv rays, fortunately they don’t exist naturally on earth’s surface. UV-C are obtained from artificial light sources like lasers and lamps mostly for disinfecting purposes. UVC ultraviolet light rays are commonly applied in industrial techniques and commercial uses, in healthcare and other sterile facilities.
Ultraviolet Radiation UVA vs UVB Protection
Why Broad Spectrum Matters
Broad-spectrum consideration is crucial for a comprehensive protection against both UVA, UVB and at times, UVC rays. Sure, our skin health needs vitamin D from the sun, however, too much sun exposure can damage our DNA cells. Not only does uv radiation cause skin cancer and premature aging, it can also affect eye health and immune system. Long term ultraviolet exposure can risk developing eye conditions like cataracts, macular degeneration and other eye diseases. Ultraviolet radiation also compromises our immune defences, making our bodies vulnerable to diseases and infections.
Sun Protection Factor (SPF) against UVA & UVB
Skincare products with broad-spectrum UV protection can mitigate these adverse health effects. Therefore, when selecting a sunscreen for instance, ensure you get one that offers broad-spectrum ultraviolet protection. Using a broad-spectrum sunscreen or sunblock with an SPF (sun protection factor) of 30 or higher (eg, SPF 50) is able to shield or absorb both UVA and UVB rays to protect our skin from ultraviolet radiation.
How Broad-Spectrum Works
Broad spectrum works by creating a protective barrier using physical blockers and chemical absorbers. The blockers deflect and scatter the uv rays, while the absorbers draw in UV radiation and converts it into thermal energy, which then gets released as waste heat. Together, these components work to shield against different wavelengths of UV radiation to provide broad-spectrum protection for the skin.
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