Sunscreen. It’s that one skincare essential that every doctor insists you should never skip, no matter what. Whether you’re visiting a dermatologist’s office, scrolling through a skincare influencer’s TikTok, or chatting with that friend who knows all things skincare (we all have one), you’ll hear the same advice: SPF is non-negotiable.
But while most of us follow this advice, we may not actually know why SPF is so crucial or what makes it such a praised step in our routines. So, let’s get into everything you need to know about SPF—what it is and how it works—in the first part of our Sunsational SPF Series!
What is SPF and What Does It Stand For?
SPF, or Sun Protection Factor, measures how long a sunscreen will protect your skin from UV rays. The higher the SPF, the longer the protection lasts. However, SPF isn’t just about time—it's also a measure of the level of protection from UVB rays (the rays responsible for sunburn).
What Does the SPF Number Mean?
You’ve probably noticed numbers like 30, 50, or even higher on sunscreen bottles—but what do these numbers actually mean? Is a higher number always better?
In simple terms, the SPF (Sun Protection Factor) number tells you how much longer you can stay in the sun without burning, compared to not wearing any sunscreen. For example, if your skin normally starts to burn after 10 minutes of sun exposure without sunscreen, using an SPF 10 sunscreen would theoretically allow you to stay in the sun 10 times longer, or for 100 minutes, before burning.
However, this is only an approximation, as burn times vary based on factors like weather, location, skin type, and activity.
Protection Levels and the SPF Scale
SPF levels come in various numbers, indicating the concentration of UV-blocking filters in the formula. Generally, the most common SPF ratings you’ll find on products offer the following levels of UVB protection:
- SPF 15 blocks about 93% of UVB rays.
- SPF 30 blocks about 97% of UVB rays.
- SPF 50 blocks about 98% of UVB rays.
- SPF 100 blocks about 99% of UVB rays.
SPF 30 or SPF 50: What's the Difference?
While higher SPF offers more protection, the increase becomes minimal at higher numbers. SPF 50 offers around 98% protection, whereas SPF 30 provides about 96.7%. SPF 30 or 50 is often sufficient for daily use when applied correctly and reapplied as needed.
Why Not Use a Really High SPF?
SPFs of 75, 100, or higher may seem appealing, but they can create a false sense of security. While they do provide higher UVB protection, they don't necessarily increase UVA protection proportionally.
For true broad-spectrum coverage, UVA protection should ideally be at least one-third of the UVB protection. Even high-SPF sunscreens can’t block 100% of the sun’s rays, so they shouldn’t replace other protective measures like reapplying regularly and seeking shade.
Most dermatologists recommend SPF 30 to 50 for effective, balanced protection—meaning that splurging on SPF 100+ may not be necessary for everyday use.
UVA and UVB Rays Explained
Another area where many people are left in the dark is understanding UVA and UVB rays—specifically, what they are and how they differ.
- UVA Rays ("A" for Ageing) UVA rays penetrate deeply into the skin, contributing to signs of ageing like wrinkles and fine lines. They are present year-round and can pass through clouds and windows, making daily broad-spectrum protection essential.
- UVB Rays ("B" for Burning) UVB rays vary in intensity depending on the time of day, season, and location. They can cause sunburns and are also associated with skin cancer. UVB exposure is higher at higher altitudes and closer to the equator.
The Effects of UV Radiation on Skin
UV radiation, particularly UVA (Ultraviolet A) and UVB (Ultraviolet B) rays can cause significant damage to your skin, even on cloudy days. Over time, exposure to these harmful rays can lead to premature aging, sunburn, and increased risk of skin cancer.
UVA rays (which penetrate deeper into the skin) contribute to wrinkles and age spots, while UVB rays (which affect the outer layers of the skin) are primarily responsible for sunburn. Both types of radiation can weaken the skin's natural defenses, leading to long-term damage. That’s why proper sun protection is essential to safeguard your skin’s health.
How to Apply SPF Properly
Proper application of sunscreen is essential for maximising protection from harmful UV rays. Here’s a simple guide to ensure you’re applying SPF effectively:
For the Body
- Adults: Use approximately 30ml (about a shot glass full) of sunscreen for full-body coverage. Don’t forget those often-missed areas like your back, ears, and the tops of your feet!
- Children (Ages 5-10): About 15-20 ml should suffice for adequate coverage.
For the Face and Neck
- Two-Finger Rule: To measure the right amount for your face, use the two-finger rule. Squeeze a line of sunscreen along the length of your index and middle fingers—this will give you enough product for optimal coverage.
- Apply sunscreen as the final step of your skincare routine. Make sure to cover your face, neck, and chest thoroughly.
Timing Matters
- For Chemical Sunscreens: Apply 20-30 minutes before sun exposure. This allows the ingredients to absorb properly and provide the protection you need.
- For Mineral Sunscreens: These provide instant protection, so you can apply them right before heading outdoors.
How Often Should You Reapply SPF?
Even though SPF 50 should theoretically protect your skin 50 times longer than it would naturally, it’s super important to reapply every two hours. If you're swimming or sweating, you'll want to reapply even more frequently to keep that protection going strong. Having a travel-size sunscreen ready in your bag ensures you're covered throughout the day!
And let’s be real—who wants to deal with sticky hands when applying sunscreen? That’s where sunscreen sticks come in! They make it easy to apply without making a mess. Got makeup on and don’t want to ruin your look? No worries! There are sunscreen sprays available that can save your makeup while keeping your skin protected. Basically, sunscreen is a no-exception rule for everyone!
The Takeaway is to Stay Protected!
We hope you enjoyed this (lengthier than usual) article! Was it informative? Fun to read? Did you learn something new? While it's always wise to heed the advice of dermatologists, understanding the reasoning behind their recommendations is equally important. We hope this information strengthens your commitment to following all the guidelines for applying sunscreen, ensuring you stay covered and protected while still enjoying the sunny weather! Stay tuned for the next two instalments in our Sunsational SPF series, where we’ll talk about the importance of sunscreen!
