What are Ultraviolet Rays?
The sun is the strongest contributor to ultra violet radiation. There are three wave lengths of ultraviolet rays- UVC short rays, UVB medium rays and UVA long rays. UVC is the most damaging but it is filtered by the atmosphere so doesn't reach the earth. UVB rays penetrate the superficial layers of the skin and are responsible for delayed sun tan, can cause sunburn and skin cancer. UVA rays are responsible for 95% of ultraviolet radiation and can penetrate down to the dermal layers of the skin and causing premature ageing and skin cancer.
UV levels are affected by the height of the sun as it moves throughout the day, so the higher the sun the stronger the ultraviolet radiation levels. It is recommended to avoid direct sunlight when the sun is strongest during the middle of the day.
Latitude is also a UV index factor, the closer to the equator the warmer the climate and stronger the ultraviolet radiation. Ozone levels and ground reflection also affect the radiation levels. With the decrease in ozone levels the exposure to UVB rays increase and ground reflection can enhance radiation levels up to 75%. Sand reflects 15% UV rays, sea foam reflects 25% of UV rays and snow doubles UV exposure.
High Energy Visible and Blue Light are produced from electronic devices and sunlight. HEV is strong enough to break down collagen, darken pigmentation and trigger inflammation. Blue light is produced predominantly by the sun, but also by devices and LED lighting. This type of light carries a lot of energy and our bodies are not very good at blocking it, which means it can have adverse effects on everything from our vision, sleeping patterns, and even our skin if we’re not careful. Thankfully, we can protect ourselves from it with sun protection and limiting exposure.
UV Index is an international measurement of the strength of sunburn producing ultraviolet radiation. The world record was set in Bolivia, South America in 2003 with 43.3 UVI. Safe levels of exposure are between UVI 3-5 but longterm exposure to UV rays can skin cause skin damage, so it is recommended to still protect the skin and avoid direct sunlight during peak hours.
The index can be monitored the same as checking the weather temperature or wind direction. The higher the percentage the more damage it causes and can even affect the eyes. UK and Ireland 1-3 in winter months and risk of burning is quite low.
How does the skin respond to sun exposure?
The skin uses sunlight to produce Vitamin D which the body uses to build strong bones, but too much UV exposure can be detrimental for skin health. Other factors such as genetics and how the baseline colour of the skin determines the skin's natural response to the sun wether is burns or tans.
Environmental factors such as exposure of ultraviolet rays and other lifestyle factors such as screen time and Fitzpatrick Scale which shows that lighter skins are 15% more likely to suffer with signs of premature ageing and skin cancer.
Rachel Neale, associate professor at QIMR Berghofer states “The mechanism of sunburn is different to Vitamin D production, and there is a weight of evidence suggesting that applying sunscreen doesn’t seem to influence Vitamin D levels much. We’re very good at making Vitamin D. And sunscreen isn’t like being inside a room – it screens the Sun out and still lets some through.”
How Does Sunscreen Works?
The history of sunscreen started in the early 1930s, South Australian chemist H.A. Milton Blake experimented to produce a sunburn cream. Meanwhile, the founder of L'Oreal, chemist Eugene Schueller, developed a sunscreen formula in 1936. In 1938, an Austrian chemist named Franz Greiter invented one of the first big sunscreen products.
Exposure to UV radiation is the main cause of the most common forms of skin cancer. And one of the most effective ways to avoid it, of course, is sunscreen. “Any conversation on sunscreen must start with acknowledging that there is robust evidence that it prevents skin cancer,” says Richard Weller, honorary consultant dermatologist at the University of Edinburgh.
Without sun protection skin damage can occur in as little as 15 minutes, ultraviolet rays and sun damage add up over time. You can protect yourself by wearing sunscreen 365 days a year, wearing a wide brim hat and protective clothing. Sun protection should be worn by everyone of all ages and ethnicity to prevent and skin cancer, reduce signs of ageing.
To protect against UVR it is important to apply a sufficient quantity of sunscreen on all exposed body sites and not to miss any areas. In order to accomplish this, sunscreen application before sun exposure and reapplication every second hour during exposure has been recommended by the World Health Organization
Physical vs Chemical Sun Protection
Two types of UV filters can be used for sunscreen. The most commonly used are known as organic filters, which absorb UV radiation and convert it into safer radiation. Inorganic UV filters like titanium dioxide and zinc oxide – which are broadly considered safe – reflect and scatter UV radiation away from the skin.
Chemical Sunscreens absorbs UV rays
Ingredients in sunscreen turn the ultraviolet rays into heat and disperse it into the skin. Chemical sunscreen ingredients such as Octocrylene, Octinoxate, Oxybenzone, Avobenzone are often lighter and water resistant. They are suitable for most skin types, but not ideal for sensitive skins or those prone to redness
Physical Sunscreens reflect UV rays
Zinc Dioxide protects against UVB rays and is more comfortable for sensitive and younger skins. Physical sunscreens sit on the surface of the skin and create a block deflecting the UV rays back into the elements. It also tends to wash off more easily when swimming, but often contain ingredients for those more prone to redness or prickly heat such to soothe the skin in a light and breathable formula. A combination found to protect against both UVA and UVB rays are Avobenzone and Zinc Dioxide
The SPF Equation
Sunscreen has evolved since it was first started to be used and in 2006 onwards the classifications of sun protection factors and the levels of protection have been more widely monitored. Now there is an international regulation and symbolism of what is suitable and how much protection is achieved with different levels of coverage. Sun protection factor 6-10 are considered low coverage, medium starts as SPF 10-25 and SPF15 blocks up to 93% UVB rays. High protection SPF30-50 and blocks 97% UVB rays, SPF50+ is classified as very high and blocks up to 98% of UVB rays.
Broad spectrum sunscreens protect against both premature ageing UVA rays and and burning UVB rays. The top dermatologists in the United Kingdom have introduced a star rating that measures UVA protection. Products that have a UVA symbol confirms the product protects against UVA rays, which constitutes it must contain at least 1/3 of its sun protection value is an ingredient that will protect against the rays.
Without sun protection many skins will burn in 10-15 minutes. An equation to help understand the SPF protection for your skin is multiplying the number of minutes it would take you to burn without sunscreen by the SPF on the product if it is applied correctly. For example 10 minutes x SPF15 = 150 minutes protection in the sun. The recommended amount of sunscreen for initial application is 5ml or 1 teaspoon for the face, neck and decollate; and 30ml or a shot glass amount for the body. This should then be reapplied every two hours in direct sunlight.
Stay Safe in the Sun!
International Dermal Institute
Cancer Research UK
World Health Organisation
Centre for Disease Control and Prevention