Understanding Broad Spectrum Sunscreen

To realize the importance of sun protection, you must understand how the sun’s rays negatively affect your skin.  There are two basic types of ultraviolet (UV) rays that reach the earth’s surface —UVB and UVA.

Accounting for 95% of the UV radiation that reaches the earth, UVA can penetrate unfortified glass in windows and reach deeper into the dermal layer of the skin, causing damage to collagen and elastic tissue. As these rays tend to reach the layers where melanin is situated, UVA rays are the main UV ray used in tanning beds.  Thus, they play a great role in causing premature skin aging including pigmentation and wrinkle formation.  On the other hand, UVB rays, which can be blocked by unfortified glass in windows, can cause reddening of the skin and sunburn.  They also play a major role in causing skin cancer.

Considering the harmful effects of UVA and UVB, an ideal sunscreen is a BROAD SPECTRUM SUNSCREEN — one that can effectively block both UVA and UVB.

Checking The SPF

Sun protection factor (SPF) is a relative measure of how long a sunscreen will protect you from UVB rays. Theoretically,  if your skin  burns  after 20 minutes in the sun, an SPF 30 sunscreen should be able to protect your skin from burning 30 times longer (30×20= 600 minutes/10 hours).

Keep in mind, however, that these measurements should only serve as a guide as these were determined in controlled conditions, i.e. in the laboratory. SPF is also not a measure for protection against the UVA rays.

Contrary to what is shown on sunscreen bottles, no sunscreen can block 100% of UVB rays. Ultrahigh SPFs are not much more protective than SPFs of 30 or 50. SPF 30 protects against 97% of the harmful rays. Meanwhile, SPF 50 protects against 98%, and SPF 100 protects against 99 % of the harmful rays.

What the Skin Cancer Foundation USA recommends is a broad spectrum sunscreen with an SPF of 15 or higher for daily use, and SPF 30 or higher for extended hours outdoors.

Choosing Sunscreen: Cosmesis And Comfort

When choosing a sunscreen, you should also consider comfort and tolerability according to your skin type.  For instance, people with oily or acne-prone skin will feel more comfortable using non-comedogenic or non-oily sunscreen. On the other hand, a hydrating sunscreen may be more suitable for those with dry or sensitive skin. Another important factor to look at is cosmesis or the chalkiness or whiteness of the sunscreen on application. This may make the sunscreen less desirable.

Chemical And Physical Sunscreens

A chemical sunscreen is more cosmetically acceptable as it can blend nicely with skin tone. This type of sunscreen contains ingredients such as avobenzone, octinoxate and oxybenzone. Once they penetrate the skin, these substances absorb the UV rays, convert them into heat and release them from the skin.

A chemical sunscreen can also be formulated with a light, easy-spreading, non-sticky feel, making it ideal for daily use. Moreover, applying even just a small amount of chemical sunscreen can provide highly effective protection.

However, those with sensitive skin may encounter problems such as redness and itching when using chemical sunscreen. Thus, if your skin is sensitive, opt for a physical sunscreen which consists of mineral filters such as titanium dioxide and zinc oxide. These compounds stay on the skin surface and function by scattering or reflecting the sun’s rays.

Unfortunately, a physical sunscreen may cause some degree of whiteness when applied. This can be an advantage because it is easy to see where you have applied sunscreen and notice when the sunscreen has been rubbed off, ensuring better coverage and maintenance of protection.  However, physical sunscreen is often heavier and thicker than a chemical sunscreen with the same SPF, making them less suitable for oily skin. It is also less effective against UVA as compared to chemical filters.

Therefore, an ideal sunscreen would be one which has both chemical and physical sunscreen compounds coexisting in a synergistic way to create good SPF (at least 30 or higher), fragrance-free, non-irritating sunscreens in light, breathable formulations.

Sun protection can be achieved by a combination of factors, and sunscreen is just one of the many ways to protect your skin. Limiting exposure to hot midday sun, using shades and wearing protective clothing all come together to ensure effective overall sun protection.