Sun protection

What is sun protection?

Sun protection involves shielding the skin from the damaging effects of solar ultraviolet (UV) radiation.

Visible light is seldom a problem except in some specific photosensitivity disorders such as porphyrias.

Why is sun protection important?

Solar UV radiation can be classified as ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC).

• UVC — wavelength 100–280 nm; absorbed by the atmosphere.
• UVB — wavelength 290–320 nm; reaches Earth’s surface.
• UVA — wavelength 320–400 nm; reaches Earth’s surface.

Exposure to UVA and UVB radiation contributes to skin ageing and is the main cause of skin cancer (eg, basal cell carcinoma, squamous cell carcinoma, and melanoma). UVB is also the main cause of skin reddening and sunburn through damage to the upper epidermal layers of the skin.

Visible light has a longer wavelength of 400–750 nm, and can also trigger or aggravate certain photodermatoses, such as:

• Melasma
• Postinflammatory hyperpigmentation
• Lichen planus pigmentosus (probably)
• Solar urticaria
• Cutaneous porphyrias (eg, porphyria cutanea tarda)
• Uncommonly, some cases of chronic actinic dermatitis.

Sun protection methods, including sunscreen and sun protective clothing, are important in reducing these damaging effects.

The Global Solar Ultraviolet Index has become a widely used way to determine the risk of sunburn. Some people may need to take particular care because of photosensitivity. Those with lighter skin are also at a higher risk of sunburn ie, Fitzpatrick skin phototypes I–III.

Sun protection methods

Sunscreens

• Sunscreens are topical agents that can be applied to the skin to protect against UV radiation (UVR).
• Sunscreen ratings include sun protection factor (SPF), which measures the product’s ability to shield against UVB rays; and whether or not a product is ‘broad spectrum’ (ie, also protects against the longer UVA wavelengths).
  • SPF 30+ is considered high protection, and SPF 50+ offers very high protection if applied in sufficient amounts (~35mL of sunscreen for an average adult).
• It is recommended to apply sunscreen daily if the ultraviolet index is 3 or higher, and to reapply at least every 2 hours. Those living distant from the equator (such as in the UK and southern New Zealand) receive in winter less than 6% of their summer daily exposure, and sunscreen may not be required all year.
• Many sunscreens that protect against UVR do not protect against visible light. Those with photodermatoses triggered or aggravated by visible light should consider using tinted sunscreens (eg, ‘Dundee cream’), as only sunscreens that remain visible on the skin will photoprotect against visible light.

For more information, see Sunscreens.

Sun protective clothing

Sun protective clothing is clothing that is manufactured from UV-protective fabric. A UV protection factor (UPF) rating of 30+ is considered good protection.

A wide variety of everyday apparel will also provide some sun protection, particularly tightly woven and darker coloured fabrics as they let less UVR through, and loose fitting clothing (more fabric and more folds increases protection).

Clothes that protect a greater area of skin are also recommended, including:

• Hats that shade the face and neck
• Shirts or tops with long sleeves, and high collars or necklines
• Long pants or skirts
• Enclosed shoes.

For more information, see Sun protective clothing.

Shade and sun avoidance

Sunscreens and sun protective clothing are important aspects of sun protection, but do not block 100% of UVR.

It is also recommended to reduce sun exposure whenever possible, by:

• Minimising time outdoors during peak sunshine hours (~10am to 4pm in summer)
• Keeping in the shade
• Using an umbrella
• Tinting windows in vehicles and buildings.

Eyewear

Eyewear (eg, sunglasses, ski goggles, and UV-filtering prescription glasses) can be used to protect the eyes and eyelids from solar UVR exposure, which is a risk factor for a number of eye diseases, such as:

• Cataracts
• Photokeratitis
• Photoretinitis
• Macular degeneration
• Cancers of the eye (eg, ocular melanoma) and eyelids.

Darker sunglasses do not necessarily provide increased UVR protection, and labelling should be checked. Some UV-filtering contact lenses are available but these do not protect the whole eye or the eyelids. Close-fitting, wrap-around sunglasses provide the best protection against light from all directions, including reflected light off water or snow.

Sunglass standards, including regulations regarding UV filtering properties, include:

• United States of America — ANSI Z80.3-2018
• Europe — EN ISO 12312-1
• British standard — BS EN ISO 12312-1
• Canada — Z94.5-95 (R2001)
• Australia and New Zealand — AS/NZS 1067:1:2016.

It is never too early to start photoprotection - for many a significant proportion of lifetime UV exposure occurs before the age of 10 

Wide-brimmed hat and sunscreen - good photoprotection is now available with less opaque products! 

A scarf can protect the vulnerable neck if a non-brimmed hat is worn 

Other photoprotective agents

Agents found to have photoprotective and anti-photocarcinogenic properties include:

• Nicotinamide (a Vitamin B3 derivative)
• Afamelanotide (alpha-melanocyte-stimulating hormone analogue)
• Polypodium leucotomos extract.

Research in this area is ongoing. The other aspects of sun protection described above remain essential.

Vitamin D and sun protection

Vitamin D is important for bone health and calcium homeostasis. Concerns have been raised that by protecting the skin against UVB, which is involved in Vitamin D production, sunscreen use could contribute to Vitamin D deficiency.

This has not been shown to be an issue with real life use of recreational sunscreen in trials. Oral Vitamin D supplements are available if deficiency is a concern.

For more information, see Vitamin D.

Recommendations

• Apply a high SPF and broad-spectrum sunscreen daily if the ultraviolet index is 3 or higher.
• Reapply sunscreen every 2 hours, and after swimming or heavy sweating.
• Avoid sun exposure during peak sunshine hours (~10am to 4pm in summer), and stay in the shade where possible.
• Avoid intentional solar tanning.
• Choose clothing made from tightly woven and darker fabrics, clothes that cover more skin, and/or those with a UPF ≥30.
• Put on dry clothes after swimming or getting wet; wet material is often less protective.
• Be careful to protect your skin and eyes at high altitude in any season, particularly in the snow which reflects extra ultraviolet radiation.

Approved datasheets are the official source of information for medicines, including approved uses, doses, and safety information. Check the individual datasheet in your country for information about medicines.

We suggest you refer to your national drug approval agency such as the Australian Therapeutic Goods Administration (TGA), US Food and Drug Administration (FDA), UK Medicines and Healthcare products regulatory agency (MHRA) / emc, and NZ Medsafe, or a national or state-approved formulary eg, the New Zealand Formulary (NZF) and New Zealand Formulary for Children (NZFC) and the British National Formulary (BNF) and British National Formulary for Children (BNFC).