Home»Featured»Guide to UV and Sunscreen: The No.1 Thing You Need in Your Skincare Routine

Guide to UV and Sunscreen: The No.1 Thing You Need in Your Skincare Routine

Pinterest Google+

Article Index:

If we were to recommend one thing to use in your skincare routine above everything else – it would be sunscreen. The reason why Paula is such a fervent advocate of sunscreen because of the known dangers of UV light. Unprotected exposure to the sun (and UV light) has been shown to increase the risk of skin cancer and accelerate the process of aging. What sunscreen does is to block UV light from penetrating your skin and damaging it.

UV Radiation and You

There are three types of UV radiation: UVA, UVB, and UVC

UVC is filtered out naturally by the ozone layer, so what you should be concerned about are UVA and UVB rays.

UVA makes up about 95% of the UV light that reaches us and is arguably the most dangerous type of ultraviolet light because it can penetrate deep into the skin and alter DNA. This causes genetic damage and accelerates the process of aging. UVA’s penetrative ability also means that you can’t feel the effects of it, combine that with the fact that it basically exists all day long – it is no wonder why UVA is labeled as the sun’s silent killer.

Cloud cover won’t entirely save you from the damage either – cloud cover only blocks between 20-80% of UV light. If you’re indoors, unless the windows are UV-treated, you’re still being exposed to UVA light. Furthermore, if you’re in the shade, UV light is still reflected off surfaces such as water, sand, and snow.

UVB being a shorter wavelength than UVA, doesn’t penetrate skin as deep and can vary by the time of day or which hemisphere you’re located in. Unfortunately for those of us living in sunny and tropical climates near the equator, we’re exposed to more of it. UVB is what’s responsible for sunburns, skin discoloration, and it also plays a role in skin cancer.

Vitamin D Deficiency?

Vitamin D is essential to health and sun exposure is indeed one way to get it. The UVB light triggers our skin to make Vitamin D, but the trade-off is the damage that it inflicts as we’ve discussed above.

However, the reality is that we get most of our Vitamin D needs nutritionally through the foods that we consume such as dairy and fatty fish. Even if we use sunscreen, the residual UV rays which still penetrate it, combined with other exposed parts of our body will typically be sufficient for us to produce Vitamin D.

For those with Vitamin D deficiency, the cause usually boils down to age and diet. So, there is no reason to skip the daily sunscreen application!


There are two major rating systems that are used in the industry to determine the ‘strength’ or level of protection of a sunscreen. The SPF or Sun Protection Factor system is mainly used in North America, Europe, and Australia*, while the PA system is typically used in Japan and South Korean. Either way, sunscreens go through strict regulatory processes before the manufacturer can claim a certain level of protection.

Sun Protection Factor (SPF)

The SPF rating system only factors in the level of protection a sunscreen provides against UVB rays. The rating system does not work on a linear scale, which means that SPF 100 doesn’t protect twice as much as SPF 50.

To calculate the level of protection of SPF is relatively easy. SPF 50 basically means that it allows 1/50th the amount of UVB light through or about 2% (i.e. 98% protection), while SPF 100 allows 1/100th or about 1% of UVB light through (i.e. 99% protection).

The lowest amount of SPF recommended for daily use is SPF 30. However, as SPF only protects against UVB rays, and not the more harmful UVA rays, you need to look out for sunscreens labeled “Broad Spectrum” which protects against both UVA and UVB rays. Similarly to SPF, the “Broad Spectrum” claim requires regulatory testing and approval before it can be labeled on a sunscreen product.

Sunscreen vs Sunblock

Sunscreens have an SPF rating which protects from UVB rays, while sunblock only protects against the more harmful UVA rays, and won’t have an SPF rating. Broad-spectrum sunscreens would contain sunblock as they must protect against both UVA and UVB rays.

Water Resistant Sunscreens

There are only two ratings which sunscreens can be claimed as being Water Resistant – 40 mins & 80 mins. These two claims are regulated in the United States, and require the sunscreen to maintain the claimed level of protection (SPF rating) after the stated time while swimming or sweating.

*Australian Testing Procedures

While the concept of SPF is constant, Australian regulations test and certify SPF more stringently than the United States/Canada for both UVA and UVB protection. Due to this, many formulations certified to a higher SPF rating in the United States are rated lower in Australia.

Persistent Pigment Darkening (PPD)

Where SPF testing is for UVB protection, the PPD system is created to determine the level of protection against UVA rays. This rating is typically used in Europe and is a determinant component to the PA system.

The PPD method basically tests how long protected vs unprotected skin takes to tan. For example, if a product is applied to the skin and it takes 50 mins to tan, but the same unprotected skin takes 10 mins to tan, it means that tanning takes 5 times longer with the product than without. In that case, the product will have a PPD rating of 5.

Protection Grade of UVA (PA)

The PA rating system was introduced in Japan in 1996 as a 3-level rating system but updated in 2013 to a 4-level system. The PA rating system only accounts for protection against UVA rays, and not UVB rays.

The PA system uses Persistent Pigment Darkening (PPD) to test the level of protection a product has and is rated as the chart below.

Grade PPD Meaning
PA+ 2 to <4 Some UVA Protection
PA++ 4 to <8 Moderate UVA Protection
PA+++ 8 to <16 High UVA Protection
PA++++ 16 and up Extremely High UVA Protection

Is SPF or PA Better?

Both rating systems have its pros and cons. While the PA system is rated to protect you against the more harmful UVA rays which can cause deeper cellular damage and accelerated aging, it’s testing methodology leaves more to be desired.

SPF rating is tested more objectively as it measures exactly how much ultraviolet light is being blocked by the product. While PA (and PPD) is somewhat subjective as it is determined by skin tanning. The problem with that is that different people’s skin reacts differently to UV light – some naturally get tan quicker than others. Furthermore, the PA system is a bracket system, meaning that you may not know how much protection in terms of time you’re getting. If you use a product that is rated PA++, you can get roughly between 4 to 8 times protection, and that’s a wide range.

Your best bet is then to look for a product with either both an SPF and PA/PPD rating or a sunscreen with “Broad-Spectrum” labeling on it to protect you from both UVA and UVB rays.

Sunscreen Filters (Chemical vs Physical)

Sunscreens typically fall into two categories, depending on their active ingredients (or fillers).

Chemical (or more accurately ‘synthetic’) and physical (also referred to as ‘mineral’). While everything is technically a chemical, we’re using these terms because they’re the most widely understood and used.


There are two physical sunscreen ingredients: Zinc Oxide and Titanium Dioxide. These generally work by absorbing to the top layer of the skin and reflect or disperse UVA and UVB rays. Sunscreens with these ingredients are usually much gentler and are usually recommended for those with extra sensitive skin.

Another benefit to these physical sunscreens is that they do not photodegrade – meaning they don’t break down when exposed to light. So, technically, they will work almost indefinitely if they are not washed away. But, in reality, we sweat and touch our faces, so they tend to run or ‘move around’

The downside, however, is that Zinc Oxide and Titanium Dioxide tend to leave a white cast because of the nature of the ingredient. This can be mitigated in more sophisticated formulas if the manufacturer ‘grinds’ them down to micro or nanoparticles. Another option to avoid the white cast is to look out for a tinted sunscreen which matches your skin tone.


There are many different types of chemical sunscreens, but the most common ones are: Octisalate, Avobenzone, Homosalate, and Octinoxate. They all fundamentally work in a similar way – they absorb into the skin and like physical sunscreens they can scatter harmful UV rays away, and/or converting the incoming UV rays into heat which negates the harmful effects of UV.

Chemical sunscreens don’t leave a white cast and typically have lighter, more fluid textures. They’re more likely to be used in water-resistant products because they don’t have the same milky runoff look as physical sunscreens. However, the downside is that they’re not as gentle as physical sunscreens and can be sensitizing for those with extra-sensitive skin.

How Much Sunscreen to Use & How Often?

You’ll see a few different methods and opinions to how much sunscreen to use – from a coin-sized amount, to using a teaspoon to measure, or even weight/volume measurements, and this may confuse most.

But, the fact is that each of our faces (and other body parts) differ in size and area. A quarter teaspoon amount may be too little for some, and too much for others. So, what we generally recommend is to use a liberal amount and ensure that coverage is both even and complete. You don’t want to leave any areas unprotected or have patchy application.

While general reapplication guidelines call for reapplication between 2 to 4 hours, it’s actually because people don’t usually apply sunscreen correctly (evenly) or liberally enough. Sunscreen reapplication all depends on your activity level and environment you’re in.

If you’re spending time mostly indoors, and don’t really sweat (like in an office environment), then as long as you’ve applied a liberal and even layer at the start of the day, you’ll be good till the end of the day!

However, if you’re using a water-resistant sunscreen and are active outdoors, then reapply every 40 or 80 mins, depending on what the sunscreen is rated at.

Another thing you’ll probably come across is to apply sunscreen 15-30 mins before you go outside. However, this is more of a guideline rather than a rule. The reason for this is not because the sunscreen has to be absorbed in the skin before it can be “activated”, rather is to ensure that your application settles evenly on your face before you head out. Sunscreen works immediately after application.

Sunscreen should always be used during the last step of your skincare routine, right before you apply your makeup (if any)! Sunscreen not only protects your skin but also help retain the efficacy of your skincare products especially those formulated with antioxidants!

Which Sunscreen is Best for Me?

The best sunscreen is one that you love and will use daily! But finding the right one can be tricky.

The first step is to determine if you have extra sensitive skin or not, if you do, we would recommend a sunscreen with Zinc Oxide and/or Titanium Dioxide as they’re the gentlest.

The next step is to know your skin type. Your skin type will dictate the texture of sunscreen you should be using – normal to dry or very dry skin should use thicker, more emollient textured products, while oily or combination type skin should use lighter products.

Choose a sunscreen with a minimum of SPF 30, and ideally, it should be Broad Spectrum.

If you use a primer, foundation, or powder with SPF, you can still layer them above your sunscreen or daytime moisturizer. However, do give ample time for the sunscreen to fully absorb before you apply your makeup, so you get a smooth makeup application.

If you’re looking to reapply your sunscreen in the day while having makeup on, we would recommend a powder type product with SPF so you can do so without messing up your makeup.

Paula’s Choice Sunscreens

Here at Paula’s Choice, we offer a wide array of sunscreens which suits multiple skin-types and concerns, including for acne-prone skin, extra sensitive skin, and waterproof sunscreens for outdoor activities.

Shop all sunscreens

Physical Sunscreen for Oily/Combination Skin: Hydralight SPF 30Resist SPF 30
Chemical Sunscreen for Oily/Combination Skin: Skin Balancing SPF 30, Resist SPF 50

Physical Sunscreen for Dry Skin: Skin Recovery SPF 30
Chemical Sunscreen for Dry Skin: Moisture Boost SPF 30, Resist SPF 50

Sunscreen for Acne Prone Skin: Clear SPF 30
Sunscreen for Sensitive Skin: Calm SPF 30 (Dry), Calm SPF 30 (Oily/Combi)

Water Resistant Sunscreen: Extra Care Non-Greasy SPF 50
Makeup Primer with SPF: Resist Primer Serum SPF 30
Sunscreen for Men: PC4Men Daytime Protect SPF 30

Previous post

Guide to Peptides: The Cutting-Edge Miracle Skincare Ingredient?

Next post

40 Beauty Myths Busted: What Really Works for Clear, Younger-Looking Skin