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Why should we protect our skin from UVA and UVB?

It is now well-recognized that in the UK, many skin cancers arise on the right side of the face and neck. This phenomenon is due to British drivers sitting on the right side in the car, whilst driving on the left aspect of the road, so their right side is exposed to more UVA through the front side window. In Europe and the USA, the opposite is true, where the wheel is on the left side, and they drive on the right, there are more UVA and UVB damage on the left side of their face and neck.
In the UK, we all have to learn how to watch out for skin cancers and photo-ageing on the right side of our faces.

Why we should avoid unprotected sun irradiation

This Clinica London long-form article examines the role of driving and ultraviolet transmission through the glass, sun protective creams, sunglasses and clothing to help cut out damaging UVA.
There are simple, practical measures we can all take to avoid UVA damage to our skin and hence reduce the risk of skin cancer. If you do have an area of skin that you are worried about, that may represent a skin cancer, Dr Jennifer Crawley can examine the lesion and biopsy if indicated, for analysis in the laboratory.
Many skin lesions are precancerous and if left undiagnosed and untreated, can transform into an actual skin cancer. Catching skin cancer early is vital. Preventing skin cancer is essential. Therefore, we all have to know about the differences between UVA and UVB and how and when to protect our skin.
Young woman in Paris

First, let us look at what UVA and UVB are

UV (ultraviolet wavelength irradiation) is the primary cause of non-melanoma skin cancers (NMSC) such as Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). This irradiation can cause malignant melanoma of the skin, the deadliest form of skin cancer, especially in fair-skinned people.

UVA and UVB are components of UV

UVA and UVB are part of the electromagnetic light spectrum that reaches the Earth from the sun. UVA and UVB are invisible, as they are outside of the visible spectrum (700 – 400 nm). However, they penetrate the atmosphere to reach the surface of the earth and us, causing skin ageing, cataracts, skin cancer and even compromise the immune system.
UVA is longwave ultraviolet A (400 – 320nm) and makes up 95% of the sun’s irradiation (sun-rays) that reach the Earth and hence our unprotected skin. Although UVA is regarded as less intense than UVB, UVA is more prevalent (clearly as 95%) and more penetrating. UVA is there even on cloudy days as it can easily pass through clouds, and also through glass, in the home, in the office and the car, unless you take preventive measures. UVA is present from morning until night, i.e. throughout daylight and even on dull days and in winter. The problem with UVA is that we are not aware we are getting it as it does not cause the skin to go red, unlike UVB, which causes skin redness and sub-burn.
UVA penetrates the superficial layers of our skin to reach the deeper dermis, and contributes to and triggers skin cancers. It also damages the keratocytes in the basal layers of the epidermis, where skin cancers Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) arise. To add to the confusion, UVA also causes tanning (more pigment melanin produced), which is the skin response to sun damage, to try and protect it. Alas, most tanning booths emit UVA primarily hence tanning beds are dangerous for your skin. The levels of UVA can be up to 12 times more than sunlight and increases the risk of skin cancer significantly. Early exposure to tanning beds also greatly enhances the potential for malignant melanoma (MM).
The other component of sunlight is UVB, or ultraviolet B, which is shortwave irradiation (320 – 290 nm). UVB chiefly causes skin reddening and sunburn, damaging the protective outer layers of the skin, the epidermis, and contributes to ageing. UVB also has a key contributory role in tanning and skin photo-ageing, causing skin wrinkling and thinning.
UVA and UVB - Young man walking on beach

Unlike UVA; the amount of UVB varies with season, your location (latitude) and time of the day (more in summer and around midday)

UVB is also highly reflective, bouncing off water and snow, providing a “double dose effect”. This effect can obviously be worse for swimmers, sailors and skiers, who risk neck and under chin sunburn, and this is why many sportspeople look older and more wrinkly. Unfortunately, they are also getting more UVA exposure and hence are more at risk for skin cancers.
However, one of the most impacting facts about UVA versus UVB is that UVA effectively penetrates glass, whereas UVB does not. If you are sitting in your office, in your car, or even taking an UBER, you are at risk of UVA exposure and hence of skin cancer.

Sunlight is made up of UVA and UVB; UVA longwave irradiation penetrates the skin through the epidermis or the dermis and causes skin cancers, whereas UVB shortwave irradiation burns the superficial layers of the skin and causes photo-ageing (wrinkles and thin, damaged skin).”

There is also UVC, which is quite a shortwave irradiation, which does not get through the Earth’s ozone layer so that we will discount UVC in this article.
Drivers are particularly at risk of UVA skin damage since the UVA passes through the car glass windows. There have been many independent findings of increased skin cancers on the right side of the face (in the UK) attributed to driving. It has even been estimated that the skin on the right side of the body receives up to 6 times more UV radiation than the left side. If the driver’s window is open, this lets in even more UVA and UVB, whereas if the window is shut, the UVA still penetrates through. The amount it penetrates depends on the car’s make and specification. Some drivers even deliberately roll down the window to increase their suntan! Little have they realised that they are also increasing their risk of skin cancer and photo-ageing (wrinkles and skin thinning).

Car window glass, just like sky clouds, does not protect adequately from UVA, the irradiation that causes skin cancers. The cancer action of UVA is by damaging cell DNA and producing genetic mutations within the skin which can lead to skin cancer”.

Fortunately, as we learn more about the damaging effects of UVA; new forms of protection are being discovered, which we will discuss below.
UVA and UVB - Mature woman with sun hat

Five practical ways to protect yourself against UVA

  1. Stay inside the house, or office, or in the shade between 10 am and 5 pm. When inside, stay away from the window and if necessary, add a UV-protective film to your home or office window if you are sitting inside with the sun streaming in.
  2. Car driving. Have a flat UV protective film applied or tinted side and rear windows (if permitted). Some cars have moderate UVA protection by the windscreen and much less UVA protection from the side front windows. Applying UV-film to the driver window glass blocks 99.5% UV but also can block up to 20% of visible light. Find out what your car has and if you can have a specially tinted glass or apply a sunscreen film.
  3. Dress appropriately to limit UV exposure, with a wide-brimmed hat, gloves, long sleeves, not forgetting to cover the legs with a long dress or light trousers.
  4. Wear UV filtering sunglasses
  5. Apply a UVA and UVB sun-protective cream

Reduce sun exposure time

Seek the shade or stay indoors. If you go out, wear sun-protective clothing and sunscreen.

UV-films for glass

People don’t realise that they spend hours in their car getting sun-exposed. Usually, the windscreen is protective against UVA and UVB but the front side and rear windows often only protect well against UVB. Increasingly, people are opting for front side windows to have a laminated glass with two layers of glass and a tinted polyester layer, which holds back the UV, still letting through a minimum of 75% visible light. Otherwise, a thin flat UV film can be purchased easily online and applied to the side windows.

Otherwise, UVA can get through unless an additional UV filter film is applied. Some cars have reduced UVA penetrating glass in the driver’s window, so check with your manufacturer what your car has and how the sun UV absorbing protection can be improved.

The transparent window film will screen out almost 100% UVA and UVB, as long as the windows are kept closed. Don´t forget to wear sunscreen when driving, especially applied to the face, neck and hands. You should wear a long sleeve shirt or put extra sunscreen on your arms. If you have a convertible car, wear a secure sunhat and sunglasses.
See below how cars perform in their window UV protection.

A further word on car windows UV protection
From the scientific paper published in July 2016 entitled “Assessment of Levels of Ultraviolet A Light Protection in Automobile Windshields and Side Windows” by Brian S. Boxer Wachler, MD 1 JAMA Ophthalmol. 2016;134(7):772-775.
An eye surgeon and his daughter from The Boxer Wachler Vision Institute in Los Angeles looked at UVA transmission of car windows of almost 30 different cars in the USA in an attempt to understand better the daily unknown risks. They aimed to build awareness of the risk of UVA damage from sunlight radiation through the glass. They examined the UVA blockage from the front windscreen and front drivers glass windows, of 29 vehicles representing 15 manufacturers. They found very effective front windscreen UVA blockage of approximately 96% and reduced by almost 30% on the front side window. The photoprotection was due to a clear layer of plastic incorporated primarily for shatter-proofing. Side windows typically do not have this layer.
Lexus cars have the best all-around protection, including the front side windows. Surprisingly, the Mercedes tested only reduced UVA transmission by 45% – 55% at the front. Different models had different photo-transmission. 2014 Volkswagen Golfs did particularly well.
They concluded that there was a very extensive range of photoprotection between cars and between windscreens and side windows.

3. Sun-protective clothing

Sun protective clothing means clothing through which UV radiation cannot pass so easily. There are special sun-protective clothes with an ultraviolet protective factor or UVP, which indicates how much UV can penetrate. A shirt with UVP 50 can only transmit 1/50th or 2% to the skin. Laundry additives exist which can render clothes UPF high.
If you do not have special UPF clothing, you can opt to wear clothes that are naturally protective based on their weave and colour. The best are tightly woven, but loose clothes in bright or dark colours, which reflect the UV provide the best barrier to UV getting to the skin. Although pastels and bleached colours look lovely, they absorb more UV, which can then penetrate.

4. UV protective sun glasses

Sunglasses not only look classy but can protect your eyelid skin and eyes from damaging UV. Large frames and wrap around shape protect the most important area. Polarised lenses reduce glare from surfaces, therefore, are suitable for driving, water sports and skiing. They should have a UV filter which stops over 90% of UV, preferably 99 to 100%.

5. UVA UVB protective sunscreen.

You MUST have skin protection both types of UV.
The main message is that sun protection factor or SPF is a measure of protection against UVB only and indicates how long it will take the skin to redden with UVB. e.g. SPF 50 means it will take 50 times longer to redden than without any SPF.
Sunscreens work by containing chemical or/and physical substances which absorb UV. For protection against UVA, you require the following; oxybenzone, avobenzone, ecamsule, titanium dioxide and zinc oxide. There are 17 FDA recognized active ingredients that can be included in sunscreens, providing the protective film on the surface of the skin, which absorbs the UV radiation and reflects it away.
UVA and UVB - Young man on mountain in sun

A word on the skin damage caused by UVA

I read an excellent paper on the microscopic damage done by UVA to the dermis of the skin that explained to me how an even small amount of low exposure to UVA causes damage to the skin. The paper is called Dermal Damage Promoted by Repeated Low-Level UV-A1 Exposure Despite Tanning Response in Human Skin and is by Frank Wang; Noah R Smith; Bao Anh Patrick Tam; Sewon Kang, John J Voorhees, Gary J Fisher. JAMA Dermatol. 2014;150(4):401-406.
Photoaging is characterised visibly by skin wrinkling and thinning, and at the microscopic dermal level by fragmentation and reduced production of Type 1 collagen fibrils that provides the strength to the skin. UVB causes these changes by inducing matrix metalloproteinase 1 and suppressing Type 1 collagen synthesis. They examined the effect of UVA, particularly UVA1 between 340 and 400nm, which composes 75% solar irradiation and most commonly found in tanning beds. They looked at low levels UVA as found in daily life, on an expression of matrix metalloproteinase 1 and Type 1 procollagen, the precursor of Type 1 collagen. The study design was 22 healthy individuals as test subjects. They measured skin pigmentation with a chronometer under L*variable (luminescence) ranging from 0 (black) to 100 (white). They took skin samples and analysed them for gene expression using real-time polymerase chain reaction.
The researchers found the following for lightly pigmented skin (L* >65) given four exposures of UVA1 irradiation at a low dose, mimicking daily sun exposure of two hours. The first exposure darkened the skin slightly without altering matrix metalloproteinase nor Type 1 Procollagen gene expression. With further repeated UVA1 exposure, the skin steadily darkened, and there was a significant induction of matrix metalloproteinase 1 gene expression. The repeated UVA1 exposures did not suppress Type 1 procollagen expression. Translated into what is happening in the skin, they concluded that UVA1 at daily doses potentially produced photo-ageing by affecting the breakdown of collagen, not its synthesis. These are known as collagenolytic changes.
The recommended approach for optimal photoprotection skin is that both UVA and UVB should be filtered out using sunscreen.

You can and should still go outside

Enjoy the sun, but be aware of the genuine dangers of UVA and UVB irradiation and protect your skin not just when you are outside in the sun, but even on cloudy days, and when you are in your car or your home or office.
We are all exposed a lot more than we realise to UVA and UVB.
Sunlight is good for us as it promotes the synthesis of Vitamin D3, an essential vitamin for bone growth, heart and skin. If you are at risk of Vitamin D deficiency VDD because you are elderly, live in a northern climate and are covered with lots clothes, or pregnant, consider taking daily Vitamin D supplements.
Consultant Dermatologist Dr Jennifer Crawley at Clinica London often diagnoses and treats patients with skin cancers, which are related to UVA (Ultraviolet A). UVA irradiation is invisible and is present even on cloudy days, from sunrise to sunset. As well as skin cancers, UVA contributes to eye surface cancers and cataract.

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