People are just realising what the letters, numbers and symbols on sun cream bottles really mean

SUN cream bottles are covered in letters, numbers and funny-looking symbols - but what does it all mean?

Here, we decipher the jargon to keep you safe this summer.

It's important to remember, however, that no matter how much protection a product claims to offer, nothing can provide 100 per cent security.

Sunscreen should be used alongside other precautions like hats, sunglasses and plenty of time in the shade.

Not taking the right measures can result in some pretty painful burns and increase your chances of developing skin cancer, Cancer Research UK warns.

SPF

SPF - or sun protection factor - indicates how well a product protects against sunburn.

The number that follows tells you how long it would take for the sun's UV radiation to redden the skin when using the product exactly as directed, compared to not wearing it at all.

The higher the number, the longer the protection will last.

For example, if you usually begin to burn after 10 minutes in the sun, a lotion with SP15 will protect you for 15 times longer than that, meaning up to 150 minutes.

But this is just an estimate, and factors like skin tone, the season, weather conditions and geography can change things, according to Nivea.

SPFs are rated on a scale of two to 50-plus.

The NHS recommends using a sunscreen with an SPF of at least 30.

This allows about three per cent of UVB to penetrate the skin, while SPF50 allows about two per cent.

This may seem like a small difference, but it can be huge on certain skin types.

Chemical vs. mineral

There are two types of sunscreen - chemical and mineral.

Products with chemical active ingredients absorb UV rays, while mineral ones (also known as physical) reflect it, according to the British Skin Foundation (BSF).

Another name for mineral sun cream is sun block, as it creates a physical barrier that sits on the skin.

Different SPF levels block varying UVB rays:

• SPF15 - 93 per cent
• SPF30 - 96.7 per cent
• SPF50 - 98 per cent
• SPF100 - 99 per cent

UVB rays can never be totally filtered, which is why it is important to reapply sun cream at least every two hours.

Chemical lotions should also be slathered on 15 to 30 minutes before heading out as it takes time for it to fully absorb into the skin.

UVA

The sun emits two types of ultraviolet rays that are damaging to the skin - UVA and UVB.

Both cause different types of damage, and not all products protect against them in the same way.

UVA rays penetrate the skin more deeply than UVB, and cause long-term damage like wrinkles, sagging, sun spots, leathery skin and other signs of ageing.

They are present at all times of day and can pass through clouds and even glass.

Bottles will carry a UVA rating out of five.

This indicates the percentage of UVA radiation that’s absorbed by that particular sun protection, compared to UVB.

The higher the number, the better the protection.

The NHS recommends always using a sun cream with at least a four-star score, or the European approval mark.

The three letters in a circle show it meets the EU standard.

UVB

UVB rays damage the skin's upper surface and are the main cause of sunburn.

While they don't penetrate as deeply as UVA rays, they are just as damaging.

They play a large part in the development of skin cancers, including melanoma.

Broad spectrum

Another phrase to look out for when choosing your sun cream is "broad spectrum".

The term means the product offers protection against both UVA and UVB rays.

It isn't always on the label, but it's an easy way to find a bottle that offers adequate protection.

PA rating

PA ratings are sometimes seen on international sunscreens, particularly those from parts of Asia.

It's another way of rating the UVA protection, the BSF says.

The letters PA stand for "protection grade" and are followed by a number of plus signs - PA+, PA++, PA+++ and PA++++.

PA+ offers some UVA protection, while PA++++ offers extremely high UVA protection.

Water resistant

No sunscreen is 100 per cent waterproof, but some claim to be "water resistant".

Manufacturers can use the term if tests show the SPF drops by up to 50 per cent after two 20-minute periods of immersion.

But it is still vital to reapply after being in the water, towel drying or sweating.

12M

Finally, on the back of the bottle of every sun cream will be a symbol that looks like an open jar next to the letter 'M'.

This represents how many months the product can last after being opened.

It's important for any cosmetic product, but especially sunscreen as it can stop providing protection once expired.

For example, 12M would mean your lotion will last for one year once you've taken the cap off, while 6M means you can use it for the next six months.

The BSF said: "Check the expiry date of your sunscreen, as out of date sunscreen will not be as effective and you risk burning."

It's a good idea to use a Sharpie to write the date you opened a bottle on the back to keep yourself safe.

Skin cancer is the most common form of cancer in the UK.

At least 100,000 new cases are diagnosed each year, and the disease kills more than 2,500 annually.

UV exposure is the main preventable cause of skin cancer. 

Experiencing severe sunburn, particularly in childhood, increases the risk of developing it in later life.