Archive for October, 2008

How Does Sunscreen Work?

Sunscreens are skin care formulations that have been developed to protect skin from damage that may be caused by exposure to the sun’s UVA and UVB rays. While we’ve been told for years that we must apply religiously if we wish to protect ourselves against sunburns and long term skin damage such as wrinkles, skin discolorations and some types of skin cancers, how does sunscreen work?

A fairly recent phenomenon, sunscreens are thought to have been developed by a chemist in 1938. But it wasn’t until 1944 that they became widely used. In the 1950s, zinc oxide, a broad spectrum UVA/UVB blocking sun filter came into use. Since then, others have been discovered or developed and we now have a range of different sunscreens to choose from. Let’s examine how they work in a bit more detail.

Chemical Vs Physical Sunscreens

Let’s examine the ingredients that make up sunscreens – sun filters - in order to appreciate how does sunscreen work. Sun filters may be divided into two types. Those that are physical – they work by sitting on top of the skin and reflecting or scattering sunlight. Physical filters include zinc oxide and titanium dioxide. While highly effective, they have a tendency to appear white when applied to the skin, leaving many individuals finding them unappealing. Newer, micronized versions tend to appear more transparent.

The other type is classified as chemical filters. Chemical filters interact with the skin’s top layer and absorb UV radiation, which is then dissipated as heat. Chemical sun filters include ingredients like Mexoryl SX, Mexoryl XL, Tinosorb M, Tinosorb S, Avobenzone amongst others.

Many sunscreens use a combination of physical and chemical sun filters to deliver optimal protection against UV rays in a pleasing formulation. 

How To Choose A Sunscreen That Works

The concept of SPF (sun protection factor) was introduced in the 1960s and since then it has become used worldwide as a way to measure the protection that a sunscreen affords against UVB protection. Most experts agree that you look for a product offering a  minimum of SPF 30 protection. It’s important to understand that protection against UVB rays is only part of what a sunscreen needs to do.

We now know that in addition to UVB rays, that UVA rays can be detrimental to our health. UVA rays penetrate skin deeper than UVB rays leading to more long term damage including wrinkles, hyperpigmentation and leathery skin. Plus both rays can contribute to some types of skin cancers.

So how does sunscreen work? As this article explains, sunscreens rely upon a combination of physical blocking, scattering and absorption of UV rays. You’ll find a range of effective sunscreens online at