SUNSCREENS

Sunscreens should be used regularly from early childhood to prevent skin damage (altered texture, wrinkling, discoloration, pronounced blood vessels, and cancerous) that may be  caused by prolonged exposure to the sun.

1. Here's a formula for judging their effectiveness: Determine how many minutes it takes your skin to begin to burn when unprotected. Multiply that number  by the Sun  Protection Factor(SPF) printed on every commercial lotion. Divide the result by 60 to find how many hours of protection you can expect. If you would normally  burn in 30 minutes, for example,  SPF 8 lotion should protect  you for 4 hours.
2. The most protective sunscreens are also the most  expensive - one with   SPF of 50 may cost four times as much as one  with  SPF of 25. To economize, buy sunscreen with SPF of 25 and apply it more often. If you burn easily or must be out  in the sun for  a long time, consult your dermatologist; she may recommend a complete sunblock such as zinc oxide.
3. Also think into account the sun's intensity; the higher in the sky it is, the more direct the rays are. You need a higher SPF number at mid-day than you do in the morning or evening. 
4. What ingredients should you look for? At one time many dermatologist recommended PABA (para aminobenzoic acid) derivatives; however, many people have developed allergic reactions to them, so doctors now suggest  you look for PABA-free sunblocks. Sunscreens should also be waterproof and non-stinging  and give broad-spectrum protection (not just against  UVA and UVB rays)
5. Even a sunscreen labeled "waterproof" may come off while swimming. Remember to reapply it.
6. Never use a sunscreen that is more than a year old. Some have expiration dates- go by them.
7. Don't rely on natural lotions like sesame oil or cocoa butter, or mixtures of vinegar and olive oil. They are not effective.