Sunlight is essential for many important bodily functions, including producing vitamin D and maintaining your circadian rhythm and mood. But too much sun exposure can also be harmful and sunscreen is a must.
UV radiation can cause short- and long-term skin damage, including sunburn, signs of aging, and even skin cancer. Prolonged exposure to UV light can put you at risk if, for example, you’re skiing or using a solarium, even if it’s not summer.
SPF or sun protection factor is a measure of the rate of sunburn-producing UV rays that reach the skin. It is important to note that sunscreens with higher SPF do not protect longer than lower SPF and must be reapplied continuously as directed, usually every two hours.
UV radiation is a form of electromagnetic energy. The sun is the most significant source of UV radiation. It’s the product of a nuclear reaction at the sun’s core, and the radiation travels to earth via the sun’s rays.
UV rays are classified according to wavelength: UVA (longest wavelength), UVB (medium wavelength), and UVC (shortest wavelength).
- They penetrate more than UVB rays, which means they can affect the deeper cells of the skin.
- They cause indirect damage to DNA.
- They cause visible effects such as wrinkles by causing premature aging of the skin. They are also associated with some skin cancers.
- Unlike UVB rays, they are not absorbed by the ozone layer. About 95 percent of the UV rays that reach the ground are UVA rays.
- They cause an instant tanning effect and sometimes sunburn. The effects tend to appear immediately.
- They can penetrate windows and clouds.
- UVB rays damage the outermost layers of the skin.
- They directly damage DNA.
- UVB rays cause most skin cancers, but they can also contribute to premature aging of the skin.
- They are partially absorbed by the ozone layer, but some rays still pass through. About 5 percent of the UV rays that reach the ground are UVB rays.
- Overexposure to UVB rays causes sunburn. Usually the effects are delayed or appear a few hours after sun exposure.
- Most solariums use a combination of UVA and UVB rays. Special tanning beds containing only UVB may be touted as safe, but they still cause skin damage. No tanning bed is safe or recommended to use.
- They do not penetrate windows and are more likely to be filtered by clouds.
There are two types of active ingredients in sunscreens: physical blockers and chemical absorbents. Chemical absorbers absorb UVA and UVB radiation, while physical blockers act as a screen to protect the skin. Many products use combinations of the two.
- Physical sunscreens contain mineral ingredients such as titanium dioxide and zinc oxide. These ingredients function to block and scatter UV rays before they penetrate the skin. Mineral sunscreens are known to leave a usually white or gray-looking rash on the skin and are usually slightly thinner than the alternative.
- Chemical sunscreens contain ingredients like avobenzone and octisalate that absorb UV rays before they can damage the skin.
The NHS and Cancer Research UK both recommend you pick a product with an SPF of at least 15, while the British Association of Dermatologists suggests we opt for at least SPF30. If your skin burns easily, it’s best to stay on the safe side and opt for a higher SPF.
How much should be applied?
The World Health Organization (WHO) recommends 35ml for the total body – that’s around seven teaspoons: one for the face/head and neck, one for each arm and each leg, and one each for your front and your back.
Not applying enough sunscreen reduces the level of protection you’ll receive. According to the WHO, applying a smaller quantity of sunscreen leads to a disproportionate reduction in protection – if the quantity applied is reduced by half, protection may fall by as much as two thirds.
When should it be applied?
The UV index is a good indicator of whether you need to apply sunscreen on any given day. The index ranges from low (one or two points) to very high (eight or more). If the index is three or more, we recommend using sunscreen. Remember, a high UV index rating does not always coincide with hot weather.
How often should it be applied?
It is best to apply sunscreen 15 minutes before going outside. Experts recommend reapplying every two hours afterward, but you’ll need to reapply more often than that if you go swimming or sweat a lot.
🌝 Make sure to spread the product evenly on your face.
👀 Cover areas that are often forgotten. Be sure to protect your hairline, hands, tops of feet, ears, and lips.
⏱️ Always wait 15 to 30 minutes for the ingredients to be absorbed by the skin before being exposed to the sun.
⏰ Sunscreens lose their effectiveness over time. Therefore, be sure to reapply at least every two hours, reapplying frequently.
👒 Don’t just rely on sunscreen. To avoid the harmful effects of the sun, also wear lip balm with sunscreen, a wide-brimmed hat, UV-protected sunglasses, and special sun-protective clothing.