Overall, the safest and most effective sun-protection products are pure zinc and/or titanium-based sunblocks. These two ingredients have been around a long time and boast great safety data. The ideal sunscreen blocks both ultraviolet A and B (UVA and UVB) rays, is stable, doesn't break down in the sun, and doesn't get absorbed through the skin.

Is there any difference between sunscreens and sunblocks?

Physical sunscreens like zinc oxide and titanium dioxide are sunblocks; they physically (like a brick wall) block both UVA and UVB rays. Besides these two, all other sunscreens are chemical-based sunscreens. Chemical sunscreens like oxybenzone, avobenzone, PABA, etc., are generally colorless and have special ingredients that filter and reduce UV rays. Not all sunscreens effectively block UVA as well as UVB rays. The chemical sunscreens break down with sun exposure and may need more frequent application.

When should I use a sunscreen?

Dr. Rothfeld recommends that everyone use sunscreen of at least SPF 15 or greater every day, year-round. If you plan to be in the sun more than 20-30 minutes a day, you should wear sunscreen of at least SPF 30. Even on cloudy days, about 80% of the sun's rays pass through the clouds. Nowadays, so many moisturizers, lotions, and makeups have sunscreen built in that it doesn't make sense to use any products that don't contain sunscreen. It just makes it so mush easier. I recommend, for example, if you wear any foundation, that there be at least an SPF 15 built in. If not, you may want to change brands.

What is SPF?

The sun protection factor (SPF) is a number that is displayed on sunscreen containers. It typically ranges from 2 to 65 (with some even higher) and refers to the product's ability to block out the harmful rays of the sun. It is calculated by comparing the amount of time needed to produce a sunburn on protected skin to the amount of time needed to cause a sunburn on unprotected skin. So, an SPF 30 means that an average person's skin will take 30 times longer before it is damaged than if the person was not wearing sunscreen.

What about sensitive skin? I break out with almost all kinds of creams. What can I use?

Sunblocks with pure zinc or titanium are the best choices for sensitive skin. (Remember that zinc oxide is actually safely used on a baby's skin for diaper rashes.) Wash off the sunscreen as soon as you get home in the evening.

How much sunscreen should I use?

Ideally, about 1 ounce (5-6 teaspoons) of sunscreen covers the entire body. Sunscreen should be applied at least 30 minutes before going outdoors and should be reapplied every two hours if you are sweating or getting wet.

At what age can I start applying sunscreen?

Experts agree that children under 6 months old should simply be kept out of direct sun. Zinc- or titanium-based sunscreens with SPF 30 or higher are great for older children.

What about that white, pasty look with zinc? Do I have to look all white to be protected?

No, not really. The newer preparations all offer microfine zinc or titanium, which blend in much better without leaving as much of a residue. Newer tinted sunblocks are also becoming available.

I used an SPF 65 lotion every two to three hours while on a tropical vacation. I still got very tan. What went wrong?

Not all SPF numbers mean the same thing. Many of the older sunscreen formulations did not block UVA rays. They blocked only UVB, which are the sun's burning rays. So, in essence, you are fooled into staying outside much longer, thinking that you never really burned. However, the UVA rays are still very damaging and can cause tanning, skin cancer, and premature wrinkling and aging.

My husband hates the greasy feel of sunscreens on his face. He refuses to put sunscreen on even though he has already had a skin cancer.

Many men (like your husband) don't like lotions and creams, especially in the summer months when they tend to sweat more. I would suggest nice alcohol-based gel type sunscreens like Clinique sunscreen gel or Coppertone Sport SPF 30. Gels may have a slight disadvantage in that they may sting a little on initial application, but they don't make you feel oily. There are also some nice sprays like Neutrogena or Presun, which are very easy to apply; a little squirt here and there, and out the door you go

Am I protected enough if I am wearing a white T-shirt?

Long ago, I was really surprised to find out that a T-shirt gives you very little protection, equivalent only to about an SPF 7 or 8! That is hardly enough sun protection. Denim clothing provides an SPF 25-30. There are clothing manufacturers like Solumbra who make cooler, high-SPF fabrics.

Some people say using sunscreen may cause skin cancer. What do you think about this?

I have not seen any reliable, large-scale scientific data to suggest this. On the contrary, everything we have seen points to excess sun as the cause of premature skin aging, wrinkling, precancers, and skin cancers. Other factors like genetics and heredity also play a role in determining who develops skin cancer, but we really have no control over our genes. We can't choose different genes or parents, so we ought to do something about what we do have control over -- our excess exposure to the damaging rays of the sun.

I've read that sunblocks cause vitamin D deficiency.

It is hard to assess this possible association. It is true that recent evidence shows many people may be deficient in vitamin D. It is recommended that daily calcium and vitamin D supplementation along with a good multivitamin is a good idea for most of us.

What other sunscreen advice do you have for us this summer?

Choose a broad spectrum sunscreen that blocks both UVA and UVB rays. I still prefer zinc- or titanium containing ones; they are pure physical blockers. Reapply, reapply, reapply! Remember that the sunscreen that sweats off or is washed off is no longer there protecting you. It is best to reapply sunscreen frequently when outdoors for a long time. I like applying a quality zinc-based sunblock before leaving home and then applying a spray sunscreen as needed for touch-ups during the day.

What general skin care tips do you give your patients?

The sun is not your friend! Our main prevention measures are aimed at sun avoidance and sun protection. These include

1. using zinc sunscreens with SPF 30,

2. using wide-brimmed hats (6 inches),

3. using physical barriers when possible like sun-protective clothing and sunglasses,

4. avoiding the peak sun hours of 10 a.m. to 4 p.m., and

5.seeking shade and staying indoors.