UVA Rays and Sun Protection

Most of us recognize that it’s the sun’s UV rays – both UVA and UVB rays that are responsible for damage to the skin over both the short and longer term.

The shorter UVB rays (wavelength between 290 and 320 nm) penetrate just to the epidermis (the top layer of skin) and are responsible primarily for Burning. UVA rays (wavelength between 320 and 400 nm) are composed of two types – UVA short (320 – 340 nm; UVA-II) and UVA long (340-400 nm; UVA-I).

Short UVA rays, like UVB rays, penetrate into the Epidermis. But long UVA rays penetrate deeper into the Dermis where they contribute to Aging (wrinkles, age spots, leather skin as well as some types of skin cancers).

Most sunscreens contain adequate protection from UVB rays. Since it is not yet mandatory in the US or Canada for manufacturers to rate the UVA protection capabilities of a sunscreen it’s up to us to do our homework.

When we choose a broad spectrum UVA/UVB blocking sunscreen it’s important to ensure that the UVA filter it contains is protecting against the whole spectrum of UVA rays.

Here is a breakdown of some of the more effective and widely used UVA filters and the range of protection that they offer:

While some studies caution us against the use of chemical sunscreens, others maintain that they deliver superior protection in more cosmetically elegant formulations than those of physical sunscreens. The choice is up to you, but here are my picks for sunscreens that will deliver protection across the UVA and UVB spectrum:

UVA Filter	UVA short protection?	UVA long protection?	Other	Physical or Chemical?
Zinc oxide	Good	Good	Good UVB protection	Physical
Titanium dioxide	Good	None	Good UVB protection	Physical
Avobenzone	Excellent	Very good	Must be stabilized as it degrades readily	Chemical
Tinosorb M	Excellent	Excellent	Excellent UVB protection	Chemical
Tinosorb S	Excellent	Good	Excellent UVB protection; highly efficient	Chemical
Mexoryl SX (ecamsule)	Excellent	Very good		Chemical
Mexoryl XL	Very good	Very good	Very good UVB protection also	Chemical