Sunscreen is one of the most important skincare steps you can take, but not all sun exposure is the same. The sun emits two types of ultraviolet radiation — UVA and UVB — and they affect your skin in very different ways.
Understanding the difference helps you choose the right sunscreen and protect your skin from premature aging, sunburn, pigmentation, and long-term damage.
This guide breaks down UVA and UVB in simple terms, explains what each one does, and shows you how to protect your skin effectively.
What Are UVA Rays?
Think of UVA rays as the “aging rays.” They penetrate deeper into the skin, reaching the dermis where collagen, elastin, and long-term structural support live.
UVA rays:
- Cause wrinkles and fine lines
- Accelerate collagen breakdown
- Trigger sun-induced pigmentation
- Penetrate glass (car windows, office windows)
- Are present all year long — even on cloudy days
UVA exposure is consistent from sunrise to sunset and is responsible for the majority of premature aging, a process called photoaging.
What Are UVB Rays?
UVB rays are the “burning rays.” They affect the top layers of the skin (the epidermis) and are the primary cause of sunburn.
UVB rays:
- Cause sunburns
- Trigger tanning response
- Play a major role in skin cancer formation
- Are strongest during spring and summer
- Do NOT penetrate glass
UVB exposure varies by season and time of day, peaking from 10am to 4pm.
UVA vs UVB: A Simple Comparison
| UVA | UVB |
|---|---|
| Ages the skin | Burns the skin |
| Penetrates deeply | Affects the surface |
| Present year-round | Stronger in summer |
| Passes through windows | Blocked by glass |
| Major cause of wrinkles | Major cause of sunburn |
The Role of Broad-Spectrum Sunscreen
A sunscreen labeled broad-spectrum protects the skin from both UVA and UVB rays. This is essential, because:
- UVB causes visible burns
- UVA causes hidden long-term damage
- Both increase the risk of skin cancer
The SPF number on your sunscreen refers only to UVB protection — which is why broad-spectrum formulas are so important.
How Much Sunscreen Do You Need?
Most adults need about a quarter teaspoon for the face and one ounce (a shot-glass amount) for the body.
Reapply:
- Every 2 hours outdoors
- After sweating or swimming
- Daily, even through clouds and windows
Best Sunscreens at Skin Boutique Online
We carry dermatologist-approved sunscreens that protect against both UVA and UVB.
- EltaMD – Lightweight protection with antioxidants.
- Sunforgettable® Total Protection™ Body Shield SPF 50 w/ EnviroScreen®
Explore our full collection:
Sunscreen Collection
UVA & UVB FAQs
Do I need sunscreen indoors?
Yes — UVA rays pass through windows.
Does SPF protect against both UVA and UVB?
SPF measures UVB protection only. Look for “broad-spectrum” for full coverage.
Are mineral or chemical sunscreens better?
Both protect well. Mineral formulas are great for sensitive skin; chemical formulas feel lighter.
Why do some people still tan with sunscreen?
UVA rays can still stimulate pigment — sunscreen reduces, not eliminates, tanning response.
Protect Your Skin Daily
Whether you’re concerned about aging, pigmentation, or long-term health, daily sun protection makes the biggest difference in how your skin looks over time.
Shop high-performance sunscreens at Skin Boutique Online and give your skin the protection it deserves.