Sunblocks and Sunscreens
at Woodbury Dental and Laser Clinic in Kent
Too much exposure to the harmful rays of the sun can cause various skin problems and conditions to develop. The natural ageing process can be hastened – and more visible signs of skin ageing can appear – when the skin is frequently and excessively exposed to the harmful UV rays.
More serious skin problems – such as skin cancer or melanoma – can be the result of excessive exposure to sunlight. It is crucial to use products that can protect the skin from the harmful UV rays, to prevent discolourations and skin pigmentation problems from occurring; protection from the sun’s harmful rays will also help in stopping more serious skin problems from developing. Sunblocks and sunscreens can provide effective protection against harmful UV rays, and may prevent the development of skin problems caused by excessive sun exposure.
What is the Difference between a Sunblock and a Sunscreen?
Sunblocks, also called physical sunscreens, are opaque formulations that work to absorb, reflect, and scatter up to 99% of both UV and visible light. Because they tend to be messy and can produce clothes stains, sunblocks are often used only on body parts that are very sensitive to the sun’s harmful rays, such as the nose, lips, ears, and the shoulders. Examples of ingredients in sunblocks are zinc oxide and titanium dioxide.
Sunscreens, also called chemical sunscreens, absorb specific wavelengths (range of 200-400 nm) and are classified as drugs by the FDA because they are “…intended to protect the structure and function of the human integument against actinic damage.” Sunscreens are considered to be more cosmetically refined due to their pleasing consistency and can typically be used over a prolonged time (for more body parts) for effective protection against the harmful rays of the sun.
UV Radiation Classifications
- UVA rays (320-400 nm) are known to penetrate the skin deeply; these rays are also known to cause aging, wrinkles and potentially even skin cancer.
- UVB rays (290-320 nm) are sunburn-causing solar rays; they can also contribute to the development of skin cancer.
- UVC rays (200-290 nm) are absorbed by gases in the earth’s atmosphere; this is a very good thing, as UVC rays are considered potentially deadly to humans.
What is an SPF?
The Sun Protection Factor (SPF) displayed on the sunscreen label can range from 2 to as high as 50; SPF refers to the sunblock or the sunscreen’s ability to block out or screen the sun’s harmful UV rays. As an example – with the use of a sunscreen with an SPF 15, a person can be in the sun 15 times longer than the time it takes for that person can go without sunscreen before burning. It is important to note that SPF protection does not increase proportionally with an increased SPF number. While an SPF of 2 will absorb 50% of ultraviolet radiation, an SPF of 15 absorbs 93%, and an SPF of 34 absorbs 97%.
The Difference between Water-Proof and Water-Resistant
How well the sunscreen stays on the skin after perspiring, swimming, or bathing is just as important as the SPF level. A product is considered as “water-resistant” if it maintains its SPF level after 40 minutes of the skin’s exposure to water. A product is considered “waterproof” if it maintains its SPF level following 80 minutes of exposure to water. When participating in outdoor recreational activities such swimming, it is best to choose a waterproof sunscreen to ensure that the skin is protected from the sun even after prolonged exposure to water.
Application of Sunscreen and Sunblock
It is highly recommended for sunscreen and sunblock to be applied to the skin about 20-30 minutes before actual sun exposure; this time frame provides time for the skin to absorb the sunscreen or sunblock, so that skin protection can be maximised. Re-application of sunblock or sunscreen is recommended after every two to three hours; re-application can also be done following a shorter period of time when profuse sweating occurs. It is best to apply sunscreen and sunblock on dry skin to ensure proper absorption; wet skin should first be wiped dry or allowed to dry naturally, before re-application of sunscreen or sunblock.