Ultraviolet (UV) radiation from the sun is a form of electromagnetic radiation. UVB causes sunburn while UVA causes permanent aging of the skin and even increase the risk of skin cancer. So it is important to strictly use sunscreen that protects from both UVA and UVB radiation. Sunscreens help shield you from the sun’s dangerous ultraviolet (UV) rays in two ways. Some work by scattering the light, reflecting it away from your body. Others absorb the UV rays before they reach your skin.
Sun is the main source in helping our bodies to manufacture vital vitamin D. However, too much sun exposure can lead to skin aging and skin cancer. It is divided into 3 types: UVA, UVB, and UVC.
UVA radiation (320 to 400 nm wavelength) is weaker than UVB and UVC, but it is the most prevalent type of sun radiation. UVA radiation can penetrate into the deeper layers of the skin and is responsible for the immediate tanning effect. Furthermore, it also contributes to skin aging and wrinkling. This radiation causes melanoma, a very dangerous type of skin cancer. As sunlight passes through the atmosphere, UVA is not filtered as significantly by the atmosphere like UVC and most UVB. Nevertheless, UVA can be effectively blocked by physical sunscreens and clothing.
UVB radiation (280 to 320 nm wavelength) has higher energy than UVA waves and is, therefore, more damaging and carcinogenic. UVB cannot penetrate beyond the superficial skin layers, but it burns our skin and causes instant damage. In short-term, it enhances skin aging and significantly promotes the development of nonmelanoma skin cancer. Most solar UVB is filtered by the ozone layer.
UVC radiation (200 to 280 nm wavelength) is the most damaging type of UV radiation, however it is successfully filtered by the ozone layer, although today, as the ozone layer is considerably thinner, scientists are concerned that dangerous, short wavelengths of sun radiation may be reaching Earth in higher amount than in the past.
UV radiation stimulates skin cell melanocytes to produce more melanin pigment. Sun radiation causes melanin to combine with oxygen, which creates the actual tan color of the skin. Melanin protects the body from absorbing excess solar radiation and the more we exposed to the sun, the more pigment is produced. The sun’s rays damage skin, our skin becomes thicker, drier, and more prone to irritation. UV radiation attacks keratin cells and fibroblasts, causing a breakdown of collagen in the skin to shut down the new collagen synthesis. In another word, the skin starts looking coarse and thick, and deep wrinkles form, and suppression of the immune system after long unprotected exposure to the sun.
Sun Protection Factor (SPF)
SPF measures the ability of how long a sunscreen will protect you from ultraviolet B (UVB) rays, the chief cause of sunburn and the main contributor to skin cancer. The SPF rating is calculated by comparing the amount of time needed to burn sunscreen-protected skin vs. unprotected skin.
Assuming you will get burn after 10 minutes in the sun, an SPF 30 will protect you for about 5 hours. But the intensity of UVB rays varies throughout the day and by location, and all sunscreens must be reapplied every 2 hours if you are in the sun. For the case of reapplication, if you have exceeded the sunscreen’s approximate maximum protection time, reapplying will not allow you to stay in the sun longer and that can lead to burning, the best choice is to head for the shade.
It is recommended to use SPF of 15 or higher to protect your skin from sunburn, reduce the risk of skin cancer and premature skin aging caused by the sun. Just a word of caution, the SPF numbers are not always a reliable measure of how much protection you will get. A higher SPF number means more sun exposure time, however, this number doesn’t increase exponentially. The percentage of UVB absorbed and overall protection of the skin increases only slightly, but many people may misinterpret these higher SPF numbers as a much higher level of protection or even a guarantee of all-day protection.
Be conscientious, avoid the sun if necessary instead of putting your faith in the SPF numbers. If you avoid the sun, get your vitamin D levels checked by your health care provider.
Along with the SPF level, you may notice PA +++ rating on the sunscreen. PA simply refers to Protection Grade of UVA rays, meaning to say the level of protection from UVA rays while SPF indicates the level of protection from UVB rays.
This Japanese measurement ranking which is now widely used is based on the Persistent Pigment Darkening (PPD) reaction reading of the sun exposure. A protective grade of sunscreen is often leveled as PA+, PA++, PA+++ with the more plus sign, the more protection from UVA rays.
According to the Japan Cosmetic Industry Association UVA protection factor for each grading of PA are listed below:
PA+ means the sunscreen can provide UVA protection with a factor of Persistent Pigment Darkening (PPD) between 2 to 4 hours of sun exposure. It can provide the protection of medium UV radiation.
PA++ can provide moderate protection against UVA rays with a factor of PPD between 4 to 8 hours of sun exposure. It is ideal for normal skin individual exposed to medium UV radiation.
PA+++ is designed for normal skin that exposes to very strong UV radiation. It provides good UVA protection with a factor of PPD of more than 8 hours. It is the highest grade of UVA protection currently available.
Classic and Mineral Sunscreens are differentiated by their active sun protection ingredients. Classic sunscreens use active chemical ingredients such as oxybenzone, avobenzone, and mexoryl designed to absorb and dissipate UVA/UVB rays.
While mineral sunscreens use mineral active ingredients such as Titanium Dioxide and Zinc Oxide to scatter and reflect UVA/UVB rays.
One more thing to take note, there is no such thing as “waterproof” or “sweatproof” sunscreens, and it is a feature of somewhat an urban myth. As per FDA regulation, sunscreen can only claimable water resistance up to 80 minutes before reapplication. Hence, it is important to reapply if you plan to be in the water longer than an hour.
Lastly, it is also best to avoid spray sunscreen, go for lotion instead. It seems to save you time from having to rub them but in fact most of the spray sunscreens, you must rub them into work. Plus it is hard to measure how much you have applied to your skin. Another drawback is, they are easily inhaled which is not ideal.
The Green Beauty Guide: Your Essential Resource to Organic and Natural Skin Care, Hair Care, Makeup, and Fragrances by Julie Gabriel