The average adult skin weighs 101 lbs. and measures 20 sq. ft. when stretched out.  This, our largest organ, is often the most neglected when it comes to protecting it from its worst enemy - the sun.  It is vital that you routinely use a form of sun protection to prevent skin damage and retard skin aging.  When purchasing, choose one with an SPF of 15 or greater and be certain that is broad spectrum (protects against both UVA and UVB rays).  Active ingredients in sun protective products can be divided into chemical versus physical agents.

Chemical sunscreens work by absorbing the energy of UV radiation before it affects your skin.  Most are composed of several active ingredients because no single chemical ingredient absorbs the entire UV spectrum (unlike physical sun blocks).  Only a few chemicals protect against the UVA region, one of which is avobenzone.
Since sunscreens are chemical in nature, they carry the potential of causing adverse skin reactions, particularly in those with sensitive skin or when used on a daily basis.

Physical sunblocks reflect or scatter UV radiation before it reaches your skin.  The two types of physical sunblocks currently available are zinc oxide and titanium dioxide.  Both provide broad spectrum UVA and UVB protection and are gentle enough for everyday use.  They are especially useful for sensitive skin because they are physical agents and not chemicals.  Consequently, they rarely cause skin irritation.