What is the difference between UVA and UVB rays?

Q: What is the difference between UVA and UVB rays?

Immediate Answer: UVB causes surface burns and damage. UVA penetrates deeper, damaging collagen and elastin, causing ageing. Both require SPF protection. "Broad spectrum" SPF protects against both. The Science: UVB (ultraviolet B): Wavelength: 280-320nm (shorter)Effect: Causes surface sunburns, skin cancersBlocked by: Clothes, glass, SPFMost damaging between 10am-4pm UVA (ultraviolet A): Wavelength: 320-400nm (longer)Effect: Penetrates deeper, ages skin (collagen damage, elastin breakdown)Blocks partially through: Clothes, but penetrates glassPresent all day, even in clouds The ageing effect is primarily from UVA (photoageing), though UVB causes sunburns and skin damage too. You need protection against both. How Nordic Formula Helps: Daycream Defence Repair SPF 50 is broad-spectrum SPF, protecting against both UVA and UVB. Use it: Every day (even cloudy days—UVA penetrates clouds)Every 2 hours if in direct sunReapply after water exposureUse generously (most people under-apply, reducing effectiveness) Pro Tip: SPF 50 blocks around 98% of UVB according to international dermatology standards (ISO 24444), and is more than sufficient. Most people under-apply sunscreen, reducing its effectiveness. Use enough that your face feels moisturised, not dry or powdery.

Question

Sun Damage & Protection

What is the difference between UVA and UVB rays?

Updated 1. January 2024

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Accepted Answer

Immediate Answer: UVB causes surface burns and damage. UVA penetrates deeper, damaging collagen and elastin, causing ageing. Both require SPF protection. "Broad spectrum" SPF protects against both.

The Science: UVB (ultraviolet B):

Wavelength: 280-320nm (shorter)
Effect: Causes surface sunburns, skin cancers
Blocked by: Clothes, glass, SPF
Most damaging between 10am-4pm

UVA (ultraviolet A):

Wavelength: 320-400nm (longer)
Effect: Penetrates deeper, ages skin (collagen damage, elastin breakdown)
Blocks partially through: Clothes, but penetrates glass
Present all day, even in clouds

The ageing effect is primarily from UVA (photoageing), though UVB causes sunburns and skin damage too. You need protection against both.

How Nordic Formula Helps: Daycream Defence Repair SPF 50 is broad-spectrum SPF, protecting against both UVA and UVB. Use it:

Every day (even cloudy days—UVA penetrates clouds)
Every 2 hours if in direct sun
Reapply after water exposure
Use generously (most people under-apply, reducing effectiveness)

Pro Tip: SPF 50 blocks around 98% of UVB according to international dermatology standards (ISO 24444), and is more than sufficient. Most people under-apply sunscreen, reducing its effectiveness. Use enough that your face feels moisturised, not dry or powdery.