Broad spectrum has become a popular label in sunscreens in recent years. This label is a statement that the sunscreen protects the user from both UVA and UVB rays.
UVB Rays
UVB, in the range of 290-320nm, are short waves of solar rays. The amount of UVB rays that we are exposed to varies depending on the season and the time of the day. During the winter, fewer UVB rays reach the earth’s surface.
Only 5% of the UV light that reaches the earth’s surface consists of UVB rays, as the rest are UVA rays that penetrate the atmosphere easier. SPF is a popular measure for the amount of protection that a sunscreen product provides against UVB light.
Earlier sunscreens focused on UVB light as it was thought to be the most damaging rays. Below are some of the effects that UVB rays can have on the skin:
- UVB rays penetrate only the surface layer of the skin but are responsible for causing sunburn-redness, inflammation, and blistering that occur after sunbathing are due to the effects of UVB exposure.
- UVB rays also stimulate and activate cells called melanocytes which are responsible for producing pigment or color. Tans are evidence of UVB damage, although a natural tan does help to protect the skin from further UV exposure to a small degree.
- UVB is also known to cause non-melanoma cancers and pre-cancers like actinic keratosis.
- UV rays cause direct DNA damage, which induces mutations that have the potential to become cancerous. UV radiation, which includes UVB and UVA radiation, is considered a class I carcinogen, which means it is a known cancer-producing agent.
- In addition to its carcinogenic properties, UVB can suppress the immune system, making you more vulnerable to infection. This immunosuppressive property is sometimes used in medical practice, for example, in treating autoimmune skin diseases like psoriasis, where controlled suppression of immune response is desired.
UVA Rays
UVA rays are long-wave solar rays ranging from 320-400nm. UVA rays can penetrate through clouds, windows, and light clothing. UVA rays can also penetrate deeper layers of the skin, and it is thought to be responsible for long-term damage to the skin, such as loss of elasticity in the skin, premature wrinkling. It may play a role in causing certain types of skin cancers.
Unlike UVB rays, we receive the same amount of UVA year-round. Hence, it is critical to use sunscreens daily, and not just for the beach in the summer.
- UVA rays are longer and penetrate deeper into the skin.
- UVA rays are thought to be responsible for wrinkles and general loss of elasticity in the skin or leathery textures on the skin surface.
- Damage from UVA rays accumulates over time and can manifest quickly around the age of 30.
- UVA damage was not well understood until recently, and some of the older sunscreens do not protect against UVA. It is important to use sunscreen that protects you from both UVB and UVA rays.
Broad-spectrum
The label broad-spectrum has become a popular label in sunscreens in recent years. This label is a statement that sunscreen protects the user from both UVA and UVB rays. Note that SPF ratings only measure a product’s capacity to block UVB light. If a product does not display either “broad-spectrum protection” or “protection from UVA light,” it is likely that it only offers protection from UVB light.
You want to ensure that you are being protected from both spectrums of light, as they are both damaging to the skin.
