Sunscreen

There are two types of active ingredients: chemical and physical.

Chemical ingredients absorb ultraviolet radiation (UVR). Physical ingredients block UVR.

Sunscreens based on chemical ingredients may cause skin reactions. Some chemical ingredients, such as oxybenzone, may get into the bloodstream.  Sunscreens based on physical ingredients do not typically cause skin reactions. I prefer physical ingredients over chemical ingredients.

UVR is divided into UVA1, UVA2, and UVB. UVB affects the top layer of the skin. UVA affects the top layer and deep layer of the skin. It is better to choose a sunscreen that block both UVA and UVB. The SPF factor only indicates how well it blocks UVB.  

There are two types of physical ingredients: Titanium Dioxide and Zinc Oxide. This table shows if they block different UVR's and if they clog pores.

Physical Filters	blocks	clogs pores
Titanium Dioxide	UVB, UVA2	yes
Zinc Oxide	UVB,UVA2, UVA1	no

I prefer zinc oxide over titanium dioxide.

Physical blockers can be further divided into non-nano particles and nanoparticles. Nano is < 100 nm. Nanoparticles can go too deep under the skin and get into the bloodstream. I prefer non-nano particles.

I prefer sunscreens that do not contain retinyl palmitate. It may cause skin tumors on sun-exposed skin.

Here are some sunscreens recommended by Environmental Working Group:

Butterbean Sunscreen Original, SPF 20.  $18.00 / 7 OZ ($2.57 / OZ)

Non-nano Uncoated Zinc Oxide 20%

Bare Belly Organics Sunscreen Cramm, SPF 30. $15.95 / 4 OZ ($3.99 / OZ)

25% Non-Nanoparticle Zinc Oxide

Badger Sport Sunscreen Cream, SPF 35. $15.28 / 2.9 oz ($5.27 / OZ)

Non-Nano Uncoated Zinc Oxide 22.5%