Protecting Your Skin From The Ultraviolet Rays-Understanding SPF and PA – What Do They Really Mean?

Introduction

As summer arrives and outdoor activities increase, UV protection cosmetics become an essential item in everyone’s daily routine. Ultraviolet (UV) rays in sunlight can darken the skin. They can cause sunspots and may contribute to visible skin changes over time.

There are three types of UV rays based on wavelength: UVA, UVB, and UVC. Fortunately, UVC is mostly blocked by the ozone layer and doesn’t reach us. Sunscreens are designed to protect the skin from UVA and UVB rays. Among them, UVA penetrates deep into the skin and contributes to fine lines, wrinkles, and signs of aging.

Just 30 minutes to an hour of sunlight is usually enough. Personally, I used to avoid the sun entirely. But I later learned that a little exposure actually helps with vitamin D—especially during winter.

Main Content

When choosing UV protection cosmetics, you’ll notice labels like SPF and PA. These indicate the product’s level of UV protection. SPF (Sun Protection Factor) refers to protection against UVB rays. While PA (Protection Grade of UVA) shows how effectively it blocks UVA rays. A higher SPF number means stronger UVB protection, and more “+” signs after PA indicate better UVA protection. If a sunscreen includes both SPF and PA on the label, it means to provide broad-spectrum protection.

What Does SPF Mean in UV Protection Cosmetics?

SPF, or Sun Protection Factor, measures how effectively a sunscreen protects your skin from UVB rays. This is the type of ultraviolet light responsible for sunburns and surface-level skin damage.

Here’s an easy way to understand it:

Your skin would normally start to turn red after 10 minutes in the sun without protection. An SPF 30 sunscreen extends your time in the sun. Without sunscreen, your skin would turn red after 10 minutes. An SPF 30 sunscreen allows you to spend more time in the sun. You can stay much longer without burning. Specifically, it lets you stay 30 times longer. This means about 300 minutes before burning—in theory.

Scientifically, SPF is calculated by comparing the minimal erythema dose. This is the smallest amount of UVB exposure that causes redness. The comparison is done with and without sunscreen.
So the formula looks like this:

SPF = MED with sunscreen / MED without sunscreen

For example:

• SPF 30 is generally considered to offer strong protection against UVB rays
• SPF 50 blocks about 98%.

SPF doesn’t increase linearly. In fact, the actual difference in UVB protection between SPF 30 and SPF 50 is only about 1.3%.

SPF values don’t increase linearly. For example SPF 30 is considered to block about 97% of UVB rays. SPF 50 may block around 98%. SPF 100 can block up to 99%. Although the numbers appear very different, the actual difference in protection is quite small.

SPF 50 allows 1/50th of UVB radiation to reach your skin. It blocks 49 out of 50 rays. SPF 30 allows 1/30th, blocking 29 out of 30 rays. The actual increase in protection is minimal.

SPF 30 = blocks 96.7% of UVB .
SPF 50 = blocks 98%
Higher SPF values may offer slightly more protection, though not linearly

Despite the big jump in numbers, SPF 50 only improves UVB protection by 1.3% over SPF 30. And even SPF 100 offers just 1% more protection than SPF 50.

So, is SPF 100 necessary?

Not necessarily. Higher SPF can offer extended protection, especially for those with extremely fair or sensitive skin. However, no sunscreen blocks 100% of UV rays. What matters more is how thoroughly and frequently you apply UV protection cosmetics—every 2 hours, and after swimming or sweating. I used to think SPF 50 was always better. But after learning how sunscreen works, I realized reapplying matters even more.

What Does PFA+ Really Mean In UV protection cosmetics

PA tells you how well a sunscreen defends your skin against UVA rays. These are the deeper-penetrating rays associated with visible signs of aging, including uneven skin tone

The PA rating system—PA+, PA++, PA+++, and PA++++—is based on the PFA (Persistent Pigment Darkening Factor),

which is a scientific measure of UVA protection.

Here’s how the PA grades are classified based on PFA values:

PFA Value	PA Rating	UVA Protection Level
2 ~ 4	PA+	Some protection
4 ~ 8	PA++	Moderate to high protection
8 or more	PA+++	Very high protection

Most modern sunscreens on the market today are rated PA+++, which means they have a PFA of 8 or higher.

How Effective Is That?

A PFA of 8 means the sunscreen allows only 1/8th of UVA rays to reach the skin. It blocks 7 out of 8 parts, or 87.5% of UVA radiation. So, PA+++ offers at least 87.5% UVA protection.

💡 You can think of it like this:
PFA 8 = 87.5% UVA blocked based on general industry data
PFA 12 = 91.6% UVA blocked
The higher the PFA, the more UVA rays are filtered out

Why the Amount of UV Protection Cosmetics You Apply Matters More Than You Think

Many people carefully choose a sunscreen with SPF 50 or even SPF 100, believing it offers superior protection. But here’s something most people overlook: how much sunscreen you apply makes a huge difference. It sometimes matters more than the SPF number itself.

Less Sunscreen = Way Less Protection

Sunscreen performance is tested based on applying 2mg per square centimeter (cm²) of skin. That’s roughly 1 gram for your face.

But what if you apply only 1mg/cm²—half the recommended amount? Here’s what happens:

• SPF drops dramatically:
  From SPF 30 to SPF 5 Using significantly less may reduce the expected level of protection.
  (That’s a decrease in protection from 97% → just 80%)

I once thought applying a small dab was enough. Turns out, I wasn’t getting even half the protection I needed. After learning the proper amount, I started noticing fewer sunspots in summer.

• PFA also drops:
  From PFA 9 → down to PFA 3
  (Blocking drops from 89% → 67% of UVA)

If you are applying too little sunscreen cuts your protection by up to 17–20

Summary – 3 Key Points to Remember

Tip: If your sunscreen feels irritating or uncomfortable, it might not suit your skin type

FAQ

How UV Protection Cosmetics Work?  Physical vs. Chemical Filters

Sunscreen is your skin’s first line of defense against the sun’s harmful ultraviolet (UV) rays. There are two main types of sunscreens:

• Physical (or mineral) sunscreens: Use ingredients like zinc oxide or titanium dioxide to reflect UV rays away from the skin. These are generally well-tolerated, less likely to cause irritation, and effective immediately after application.
• Chemical sunscreens: Contain organic compounds like PABA, which absorb UV rays before they penetrate your skin. but may not be suitable for all skin types.

Tip: Personally, chemical sunscreens tend to sting my eyes, so I stick with mineral formulas for daily use.

When choosing a sunscreen, check whether it contains physical, chemical, or hybrid ingredients depending on your skin type and usage.

What About Kids?

• Use a gentle sunscreen with SPF 15–25 and PA++ for children.
• For infants under 6 months, avoid sunscreen and opt for long sleeves and hats instead.
• Some parents choose to test a small area first, especially for sensitive skin.

Tip: My nephew had a mild rash from a regular sunscreen once. After that, we only use low-SPF mineral sunscreens designed for kids.

Tips for Using UV Protection Cosmetics Effectively

• Many people around me apply sunscreen after skincare and before makeup
• Some users prefer to avoid the eye area to reduce potential discomfort.
• For outdoor sports or swimming, choose water-resistant formulas.
• For daily indoor use, SPF 15–30 with PA+ is usually enough.
• Don’t forget ears, neck, hands, and lips—they get sun too!

Do UV Protection Cosmetics Expire?

Yes. Once opened, sunscreen should be used within 6 months.

• Store in a cool, dry place or refrigerate for longer shelf life (up to a year).
• Unused or expired sunscreen loses effectiveness—check the date before use.

Choosing the Right UV Protection Cosmetics for Your Skin

Sunscreens come in many different forms—and choosing the right one can make a big difference in both comfort and effectiveness.

Spray Sunscreen

Best for: Outdoor activities, travel, quick reapplication

• Super convenient for covering large areas like your neck, chest, arms, and legs.
• Great for applying on-the-go— I keep one in my gym bag—it’s super handy after a quick outdoor jog
• Those with dry skin might find that sprays can sometimes be drying. Follow up with moisturizer if needed.

Powder Sunscreen

Best for: Makeup-friendly reapplication

• A great choice for those who wear foundation and want a mess-free, matte finish.
• It lets you top up your sun protection. It’s a lifesaver when I’m wearing makeup at work and don’t want to ruin my base.
• It may also be helpful for those looking to reduce skin shine

Cream Sunscreen

Best for: Dry or sensitive skin, no-makeup days

• Rich and hydrating, making it perfect for people with dry skin.
• Creates a protective barrier, but may clog pores if you have oily or acne-prone skin.
• Can be tricky to reapply over makeup, as it may cause smudging or uneven patches.

Stick Sunscreen

Best for: Targeted application, dry environments, on-the-go use

• Contains oil-soluble UV filters along with waxes and petrolatum (like Vaseline), giving it a thicker texture.
• Adheres well and doesn’t easily rub off—a popular choice for men.
• ⚠️ Be mindful: Direct contact with skin can contaminate the stick if not kept clean.

Conclusion

Picking up the right sunscreen depends on your skin type, lifestyle, and needs. Remember, consistent and proper reapplication is key to keeping your skin safe from harmful UV rays all.

No sunscreen fits all. With some trial and error, I found what works best for my lifestyle. I hope this guide helps you do the same.

I’ve personally struggled with melting foundation in summer—especially during long outdoor events or commutes. I used to carry blotting paper everywhere, but it didn’t help much. Then I found a sweat-proof summer makeup tutorial that finally worked for me. It gave my makeup a smoother finish that lasted even in humid weather.