Which rays does sunscreen protect against?

RayWhat it does
UVACauses premature wrinkles and age spots, contributes to skin cancer and passes through window glass.
UVBIs the main cause of sunburn and contributes to skin cancer. Window glass blocks it.
1

UVC is another type of UV radiation, but the atmosphere absorbs all UVC from sunlight before it reaches the ground. Everyday sun protection focuses on UVA and UVB.3

How does sunscreen protect you?

Chemical, mineral and hybrid sunscreens form a protective layer that absorbs the sun's rays. Mineral sunscreens also reflect rays. Any of these types can protect against UVA and UVB when the formula offers broad spectrum protection.14

How do you get the protection on the label?

Choose broad spectrum SPF 30 or higher, with water resistance. Water resistance lasts either 40 or 80 minutes; check the label for your product's limit. It does not mean waterproof. In the UK, look for at least four stars for UVA protection; a UVA symbol inside a circle indicates that the product meets the EU standard.145

  1. 1Apply enough to cover all exposed skin, including your face, neck, ears and scalp if your hair is thinning. Around 6 to 8 teaspoons is a guide for an adult's entire body. A thin layer gives less protection.
  2. 2If you will be outside long enough to risk burning, apply sunscreen 30 minutes before leaving and again just before you go out.
  3. 3Reapply every two hours outdoors and straight after swimming, sweating or towel drying. Reapply if the sunscreen has rubbed off, following the product's directions.
5

An SPF rating describes UVB protection, so the biggest number on the bottle is not its entire CV. Check UVA protection separately rather than choosing by SPF alone. A higher SPF is not permission to stay in the sun longer.5

What else needs protection?

Visible sunlight can worsen dark spots, particularly in darker skin tones. Tinted sunscreen containing iron oxide adds protection against visible light. Choose one with broad spectrum protection and SPF 30 or higher if skin darkening is a concern.1

UV radiation cannot be seen or felt, and levels can stay high under cloud cover. Check the UV index: sun protection is recommended at 3 or above. Water, sand and snow reflect UV and increase exposure. Use shade, clothing and a brimmed hat, and protect your eyes with sunglasses offering 99 to 100% UVA and UVB protection.2

Who should take extra care?

People of every skin tone can develop skin cancer. Children, outdoor workers and people taking medicines that increase sensitivity to sunlight need extra care. So do people with many moles or a family history of skin cancer. Keep babies under six months out of direct sunlight.25

If you get sunburned, stay out of the sun until redness has gone. Seek medical help if you feel unwell or your skin swells badly or blisters. Report a new mole, growth or lump, or changes in a mole's size, shape or colour, to a doctor promptly.5

Where this answer comes from

  1. 1Sunscreen FAQsaad.org
  2. 2Ultraviolet radiationwho.int
  3. 3Ultraviolet radiationwho.int
  4. 4How to select a sunscreenaad.org
  5. 5Sunscreen and sun safetynhs.uk