How Does Sunscreen Work?
Sunscreen describes a range of products that work to minimise the impact of UV light on our skin. There are three types of UV light: UVA, UVB and UVC. UVC is absorbed by the Earth’s atmosphere so is removed before it reaches us. UVB is primarily responsible for sunburn - reddening of the skin in response to sunlight, but both UVA and UVB can contribute to less obvious damage in the form of skin aging, wrinkles and cell damaging that can potentially lead to the development of cancerous cells.
Sunscreen typically contains chemical absorbers which absorb UV light or/and physical blockers which reflect UV light to prevent UV light from reaching the skin. Examples of chemical blockers include paraminobenzoic acid or oxybenzone whereas titanium dioxide and zinc oxide are examples of physical blockers. Sunblock is a product which is composed only of physical blockers and reflects 100% of UV light. Sunscreens are classified based on their Sun Protection Factor (SPF). SPF is a measure of the sunscreen’s ability to present UV damage to the skin. SPF 20 means that your skin will burn 20 times slower with that sunscreen than without it. All skin is different so it is important to choose your sunscreen SPF according to your own tendency to burn. For the majority of us fair skinned Irish, that means the higher the factor the better. Some sunscreen protects only against UVB light, but others protect against UVA and UVB and are classified as broad spectrum.
Sunscreens are continuously being researched and developed to improve their performance. In the last decade, nanotechnology, the technology of particles less than 100 nanometers, has been employed to improve the texture and appearance of sunscreen products. Traditional sunscreen products tended to be thick heavy creams. These were difficult to spread on the skin, not very comfortable to wear, and resulted in an obvious white appearance on the skin. This was due to the size of the ingredients used in the cream, particularly the physical blockers. Large particles of titanium dioxide or zinc oxide reflect visible light, generating a white appearance. When the particle size is reduced, these materials no longer reflect light and appearance is much improved. The product also flows and feels much better with these smaller particles. While nanotechnology improved the performance and quality of sunscreen, it also came with health concerns as to the safety of applying nanoparticles to our skin. Additional research has shown that these products are completely safe for use.
So if you do see the sun – don’t get burned! Grab a broad spectrum high SPF sunscreen and enjoy the sunshine without the effects of UV radiation on your skin.
Dr Denise Croker, SSPC at MSSI, Department of Chemcial and Environmental Sciences, University of Limerick