Summer is coming, and I, like almost everyone else, love the sun. It gives us a nice tan, makes us feel full of energy, gives us vitamin D, and generally makes us feel happy. But it also gives us sunspots, speeds up the ageing of the skin, and can cause melanoma (skin cancer). That is why applying SPF and protecting our skin is very important.
What is SPF
SPF stands for sun protection factor. It is another name for sunscreen or sun cream.
SPF is something we all need to apply every day, regardless of whether it is sunny or cloudy outside. UV rays can get to us through clouds as well.
The number on the SPF product tells us how long we can be in the sun without burning. But only if applied correctly. To explain, that means that if you would usually burn in 15 minutes in the sun without protection if you apply SPF 15 (properly), you can be in the sun 15 times longer. So let’s say you applied SPF 15 at 7 in the morning before you left the house. You will have to re-apply that same SPF in 3 hours and 45 min or at 10:45. (SPF 15 x 15 min = 225 min. 225 min/60min=3h45)
But you need to take this information with a pinch of salt. Because that would mean that SPF 50 would protect you for 750min/12.5h, and that is incorrect. As SPF gets used up as it works, it degrades with exposure to the sun.
Another thing to note is that the sun is not equally strong throughout the day. It is weaker in the early morning and later evenings. So your SPF will last a bit longer at those times of the day.
But the general rule is to re-apply every few hours (2-3hours). On sunnier days, you should re-apply SPF more often than on gloomier days.
Chemical vs physical SPF
When you are buying sunscreen, you can go in two directions:
- a physical SPF
- a chemical SPF
Physical SPF
Physical SPF is sometimes also called natural or mineral SPF. That is because it uses minerals to physically reflect UVA and UVB rays away from the skin before they get a chance to penetrate the skin. But they also protect the skin by absorbing UV rays. The most commonly used minerals are titanium dioxide and zinc oxide.
Mineral sunscreens are the best option for sensitive skin. They rarely cause any allergies or irritations.
Even though it is sometimes called a natural sunscreen, it doesn’t mean it is natural. In fact, some research showed that zinc oxide and titanium dioxide are harmful to sea life as they are not biodegradable.
You can easily recognise a mineral SPF by the white cast that it leaves on the skin. That is completely normal and is the way how these types of sunscreen protect our skin. Sometimes, this problem is solved by using nano-particles of those minerals, which makes them very small micro-pigments. But many scientists advise against using the nano-particles in your sunscreen because of their possible links to cancer.
There is still not enough research to make this claim 100% correct, so the best option would be to look for a mineral sunscreen that doesn’t use nano-particles.
To summarise:
Pros of mineral SPF are:
- they are better for sensitive skin
- they are effective immediately after applying
- non-nano mineral SPF is very safe for the health and environment
- they are more stable
- they have a broader protection
Cons of mineral SPF:
- they leave a white cast on the skin
- nano-particles are deemed not safe for humans or the environment
- they are soluble in oil which can make them heavier on the skin
Examples of mineral SPFs:
Chemical SPF
Chemical filters absorb the UV rays, which protect the skin from absorbing them. They mimic the action of melanin, a skin pigment that acts as our natural filter. Melanin absorbs UV rays and causes the tanning of the skin. Unlike mineral sunscreen, this is the only way chemical sunscreen protects the skin.
The texture of chemical SPF is much lighter than the physical one, and it gets absorbed pretty much immediately. It also doesn’t leave any white residue after application.
Even though chemical filters get absorbed immediately (or within a few minutes), they need to be applied at least 15 minutes before sun exposure.
Also, not all chemical filters protect from both UVA and UVB rays. That’s why if you buy a chemical SPF, it usually has a blend of a few chemicals.
The most common ones used are:
- Avobenzone
- Homosalate
- Mexoryl SX and XL
- Octinoxate
- Octisalate
- Octocrylene
- Oxybenzone
- Tinosorb S and M
- Uvinul A plus and T150
To summarise:
Pros of the chemical SPF:
- it does not leave a white cast on the skin
- gets absorbed quickly
- they can be in non-greasy, fluid formulas
- light texture
Cons of chemical SPF:
- could irritate sensitive skin
- more unstable
- can protect from either UVA or UVB (needs a blend of a few different filters)
- not effective immediately (need to wait at least 15 minutes before sun exposure)
- some chemicals filters are accused to be endocrine disruptors
- some can generate free radicals (a particle that causes skin ageing; this can be reduced by adding an antioxidant in the skincare routine)
Examples of chemical SPF:
UVA and UVB rays
There is a difference between UV rays and the damage they do to our skin.
UVA rays
UVA rays have a longer wavelength and cause premature ageing of the skin (UV A-age). They penetrate deep into the skin and cause irreparable damage to the skin – ageing, hyperpigmentation, sun allergies, and melanoma. As UVA rays cause damage in the deep layers of the skin, our skin tries to repair itself, and that results in our skin tanning. We don’t feel the effects of UVA rays immediately after exposure which makes them even more dangerous. Also, they are there throughout the year, not just in the summer.
Skincancer.org says that ‘UVA is connected to the “broad-spectrum protection” you see on the labels of sunscreen products. Early sunscreens only protected your skin from UVB rays, but once it was understood how dangerous UVA rays were, sunscreen manufacturers began adding ingredients to protect you from both UVB and UVA across this broader spectrum.
UVA rays have the same level of strength throughout the year, and they penetrate the windows and through the clouds, which means that we get exposed to a high level of UVAs during our lifetime. They also account for 95% of the radiation that reaches the earth.
UVB rays
UVB rays have a shorter wavelength and are the ones that cause our skin to get red and burn (UV B-burn). They damage the outermost layer of the skin. Exposure to UVB rays causes the tanning and burning of the skin and, in extreme cases, blisters on the skin.
Sun protection factor is connected to the UVB ray. As I said earlier, the SPF number tells us how long it will take our skin to burn in the sun with that SPF. And UVB rays are the ones that cause burning.
Another thing to note about UVB is that its intensity fluctuates. They can damage the skin all year round, but their intensity is the strongest from late morning to mid-afternoon in warmer months (spring to fall). Also, they can be filtered and don’t penetrate through the glass.
Levels of protection
As I mentioned above, SPF is a level of protection against UVB rays. The levels are divided into four groups:
- Low 6-10
- Average 15-25
- High 30-50
- Very high 50+
There is also a classification for UVA protection. It is called a PA. According to btyaly, ‘The PA is a Japanese classification system that measures protection against UVA rays. The PA index is rated with +, which ranges from 1 to 4 (+, ++, +++ or ++++). The higher the PA, the stronger the protection against UVA. Some products may also have the UVA circled label on the bottle to indicate that they contain filters that protect against UVA.’
If the product doesn’t have any UVA protection specification, UVA is usually a third of the UVB factor. So if the product is SPF 30, UVA protection is 10, which is not high enough.
How much and which SPF do you need
In the tests they do in the laboratories of the cosmetics, they use 2mg of product per cm2 of the skin. That is equal to 1/2 teaspoon (or 2.5 ml) for the face, neck, and ears. Or half that amount for the face only. If you use this amount of sunscreen, it will give you the protection that says on the bottle.
If you have sensitive skin, mineral SPF is the best choice for you.
For oily skin, a chemical one will be a better choice.
But regardless of the type of sunscreen you choose, always look for a full-spectrum SPF that will protect you from both UVA and UVB rays. And make sure it has at least SPF 30.
Conclusion
Protecting our skin is very important, not just for aesthetic reasons but also for health reasons.
Make it your routine to put SPF products on as the last step of your skincare every day.
And make sure you use enough of it. Half a teaspoon for your face, neck and ears will provide you with much-needed sun protection.
If you are using your sunscreen correctly, one bottle of facial SPF will last you around a month.
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Do you use an SPF every day or just in the summer? Which is your favourite one?
