Photoprotection – Protecting our skin from the sun!

Photoprotection – Protecting our skin from the sun!

Why do we need photoprotection?

Photoprotection is required to reduce ultraviolet (UV) radiation induced skin damage, photo-aging and skin cancers. Photoprotection includes sunscreens, clothing, hats and sunglasses.

What is UV radiation?

UV radiation affects the skin by causing ageing, sunburns, precancerous lesions, cancerous lesions and immunosuppression. There are 3 types of UVA radiation: UVC, UVB and UVA. UVA is associated with ageing and pigmentation, it produces free radical oxygen species, indirectly damaging DNA. UVB causes sunburn and DNA damage associated with non-melanoma skin cancers.

What is SPF?

SPF stands for sun protection factor and indicates the degree of sunburn protection given by sunscreens. It is a primary measure of UVB and to a lesser extent UVA. For a sun cream to be effective it needs to be applied liberally and 20 minutes before going outdoors.

What type of sunscreen should I use?

A broad-spectrum sunscreen, which involves UVA and UVB coverage, providing water resistance and a high sun-protection factor (SPF 30 or 50) should be used. Included in many sunscreens are antioxidants such as vitamin C, vitamin E and green tea polyphenols which can give additive protective effects. You many need to change the type of sunscreen you use according to what activity you are planning to do.

How should I apply sunscreen?

Apply 20 minutes before sun exposure. Reapply after 2 hours, after sweating or swimming.

An adult requires 30 ml /body (2 tablespoons), with a teaspoon (5ml) used on the face, head and neck.

For children the requirements vary according to size for example; 3 years: 10 ml (2 teaspoons), 7 years: 15 ml (3 teaspoons), 10 years: 20 ml (4teaspoons).

Is it ok for babies to wear sunscreen?

It is safe and recommended to use sunscreen in babies over 6 months. The best way to ensure babies and children are protected is to provide as much shade as possible, use protective clothing, hats and sunglasses. Physical sunscreens are less likely to irritate sensitive skin and eyes.

It is recommended that parents of babies under 6 months should consult a doctor before sunscreen use. This is due to the lack of development of metabolism and excretion of the chemically absorbed agents within sunscreen. If sunscreen is necessary, it should be limited and infrequently used on sun-exposed regions only.


Physical versus Chemical Sunscreen

 What is a mineral or physical sunscreen?

Physical sunscreens consist of mineral ingredients namely, zinc oxide and titanium dioxide. They work by sitting on top of the skin and they reflect and scatter light in a similar way to clothing. Zinc oxide protects against a wide range of UVA including UVA 1 (340 to 400 nm). It is very photo-stable and does not react with other UV filters. It is more effective than titanium dioxide in regards to UVA protection however, it is less efficient against UVB radiation. Titanium dioxide protects against UVA 2 (315-340 nm) and UVB, but does not protect against UVA 1 as does zinc oxide.

What are the pro’s and con’s of physical sunscreens?

Physical sunscreens work as soon as they are applied on the skin. They are unlikely to irritate the skin so they are good for sensitive skin types. They can also be good for rosacea skin types or patients with redness as they deflect heat from the skin. They are less likely to be pore-clogging so they are good for acne prone skin. They last longer when in direct UV light, however, they can be rubbed off much more easily that chemical sunscreens especially if in contact with sweat or water. They can often leave white streaks or a white chalkiness on the skin so they are not ideal for under make-up and can be difficult to use for darker skin tones. They tend to be thicker requiring more effort to rub in.  They also tend to have a longer shelf life.

What is a chemical or organic sunscreen?

Chemical sunscreens contain organic (carbon-based) compounds e.g. oxybenzone, octinoxate, octisalate and avobenzone. They create a chemical reaction and work by changing UV rays into heat and then release that heat from the skin. They consist of UVA and UVB blockers. Their structure allows for light to be absorbed.

What are the pro’s and con’s of a chemical sunscreen?

They are usually thinner formulations which makes application easy, they do not cause much white streaking and spread easily. They are much more resistant to sweat or water compared to a physical sunscreen. They only start to be effective about 20 minutes after application to the skin and they require frequent reapplication as its protections gets used up more quickly in direct sun light. They are more likely to be irritating and the higher the SPF they higher the risk of irritation. They can increase redness in rosacea prone skin types and they can also clog pores causing an acne flare.

Physical or chemical sunscreen, which is best?

The simple answer is… the one that feels the most comfortable on your skin. If you’re an oilier skin type you will want to choose one that is lightweight and not greasy. If you have sensitive skin that gets red easily you’ll want to find one that doesn’t irritate. If you have a darker skin tone you will want to choose one that doesn’t look chalky on the skin. Both chemical and physical sunscreens do a great job at protecting your skin from the sun. The most important thing is to find a sunscreen that you like the look and feel of, so that you are inclined to use it frequently and reapply regularly. If you are concerned about the compatibility of your skin and a new sunscreen performing a simple patch test on your inner arm is a good idea, before using it all over your face.


Dr Kara Heelan