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Author: sharmani | Total views: 311 Comments: 0
Word Count: 761 Date: Fri, 5 Dec 2008 4:04 PM

Physical VS Chemical Sunscreens: What's The Difference?

If you're perplexed by the vast array of sunscreens found in any drugstore, then deciding whether to choose a physical vs chemical sunscreen can be just as confusing as deciding which SPF, water resistant or non water resistant, spray, lotion or cream. You can take some comfort in the fact that you're not alone. Each year, manufacturers come up with new packaging, slick ads and clever marketing campaigns to try to get you to choose their product over their competitors.

So how to know which is better - a physical or a chemical sunscreen? If formulated properly and with the correct ingredients in adequate concentration, both types of sunscreen can deliver effective protection against the sun's UVA and UVB rays. Where opinions differ lies in personal preference and individual tolerability.

How Do Physical and Chemical Sunscreens Differ?

Technically a sunscreen is composed of sun filters. These are agents that either block, deflect or reflect UV rays. And, many sunscreens often use a combination of both physical and chemical blockers to achieve optimal results.

Physical filters include zinc oxide and titanium dioxide. They work by sitting on top of skin and either reflecting or scattering UV rays. Zinc oxide can block against both UVA and UVB rays, covering the whole spectrum, while titanium dioxide only delivers protection from UVB rays. An effective physical sunscreen should contain zinc oxide and/or titanium dioxide. Both work well, but have a tendency to leave a white cast on skin. Newer, micronized versions or those that contain nanoparticles don't seem to be as problematic.

Chemical filters comprise a range of ingredients synthesized in a lab. These include avobenzone (also known as Parsol 1789), oxybenzone, Tinosorb M, Tinosorb S, Mexoryl SX and Mexoryl XL amongst others. These agents work by interacting with the skin's top layer to absorb UV rays and convert them into energy before they can harm skin. Chemical sunscreens tend to use a combination of ingredients to protect against the full spectrum of UV rays. And some formulations may also incorporate a physical filter.

While older chemical filters tended to protect well against UVB rays, they often didn't deliver much in the way of UVA protection. Newer filters such as Mexoryl and Tinosorb now deliver UVA protection so look for sunscreens containing those. Avobenzone also offers UVA blocking capability, but one problem is that it tends to degrade upon exposure to light. If you are using a sunscreen that contains avobenzone ensure that it is stabilized with an ingredient such as Octocrylene as found in some ranges including Anthelios sunscreens.

Which One's Right For You?

Now that you know how physical and chemical sunscreens differ, how do you decide which one's right for you? If you have sensitive skin, then a purely physical blocking sunscreen with zinc oxide or titanium dioxide might be the best choice. These ingredients are well tolerated and tend not to irritate skin. They may also be ideal for use in children whose skin is more sensitive than that of an adult's. While effective, the downside is that physical sunscreens can look white on skin, particularly problematic if you are not fair skinned. Tinted formulations may be more palatable and it may be useful to try a number of brands before finding one that works for you.

Many chemical sunscreens offer the advantage of going and staying on clear. This is extremely important if sunscreen is part of your beauty regimen and if you are using one daily. And, if you are darker skinned, then a chemical sunscreen might be an obvious choice in order to avoid the white cast associated with many physical sunscreens. Newer sun filters such as Mexoryl XL, Mexoryl SX, Tinosorb M and Tinosorb S can be formulated into very light, yet highly effective products. Like physical sunscreens, they are available in a range of formulations including sprays, lotions and creams so it's easy to find one that works for your skin type.

As with any sunscreen, how you apply will affect its efficacy. For maximum effect, apply sunscreen 15 to 20 minutes prior to UV exposure to ensure that it is absorbed sufficiently to protect. If you have a tendency to sweat or will be engaged in water activities, look for water resistant or very water resistant formulations, which will give you between 40 to 80 minutes of protection. And, as directed on most sunscreen packages, reapply every 2 hours and more frequently if you've been exposed to water.