Whether the sun is shining brightly on you or hiding behind a thick layer of clouds, its rays are still present and can run havoc on your skin.

Make sunscreen a part of your daily morning regiment and protect your skin from the harshness of the sun.

Below are some facts to help you learn more about sunscreen and why it should be your best friend.

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What Are Sunscreens?

Sunscreens are chemical agents that help prevent the sun's ultraviolet (UV) radiation from reaching the skin. Two types of ultraviolet radiation, UVA and UVB, damage the skin and increase your risk of skin cancer. The ingredients in sunscreen protect the skin by absorbing, blocking or scattering UV radiation.UVB is the chief culprit behind sunburn, while UVA rays, which penetrate the skin more deeply, are associated with wrinkling, leathering, sagging, and other effects of photo aging. They also exacerbate the carcinogenic effects of UVB rays, and increasingly are being seen as a cause of skin cancer on their own. Sunscreens vary in their ability to protect against UVA and UVB.

Who Should Use Sunscreen?

Anyone over the age of six months should use a sunscreen daily. Even those who work inside are exposed to ultraviolet radiation for brief periods throughout the day. Also, UVA is not blocked by most windows.

Children under the age of six months should not be exposed to the sun. Shade and protective clothing are the best ways to protect infants from the sun.

What Is SPF?

SPF — or Sun Protection Factor — is a measure of a sunscreen's ability to prevent UVB from damaging the skin. Here's how it works: If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about five hours.

Another way to look at it is in terms of percentages: SPF 15 blocks approximately 93 percent of all incoming UVB rays. SPF 30 blocks 97 percent; and SPF 50 blocks 98 percent. They may seem like negligible differences, but if you are light-sensitive, or have a history of skin cancer, those extra percentages will make a difference.

But there are problems with the SPF model: First, no sunscreen, regardless of strength, should be expected to stay effective longer than two hours without reapplication. Second, "reddening" of the skin is a reaction to UVB rays alone and tells you little about what UVA damage you may be getting. Plenty of damage can be done without the red flag of sunburn being raised.

What is PA?

Newer sunscreens in the market also contain UVA-filters and their protective effect against UVA is measured with PA. PA stands for Protection Grade of UVA. The U.S. FDA currently does not offer a rating system for UVA. PA is a designation that originated in Asia and is used globally.

There are three grades, namely PA+, PA++ and PA+++.The more +, the more protection a sunscreen offers against UVA. PA+++ offers the most protection.

UVA is long wavelength (320-400 mm) UV. UVA radiation can penetrate glass and clouds and can be 30 to 50 times more prevalent than UVB rays. UVA rays can penetrate into the deep layers of the skin and cause skin aging, wrinkles, and skin cancers.

UVB is middle-range (290-320 mm) UV. UVB rays do not penetrate glass. Although UVB is less penetrative than UVA, UVB is more intense. UVB causes burning, tanning, acceleration of skin aging and the development of skin cancer.

Benefits of Sunscreen

- Minimize the effects of UVA and UVB.

- Shield important proteins such as collagen, elastin, and keratin.

- Protect skin from developing too high concentration of melanin which causes age spots and freckles.

- Help prevent skin from developing skin cancers.

How to Choose Sunscreen?

Select a sunscreen that provides broad-spectrum protection, UVA/UVB protection. Look for sunscreen with zinc oxide and/or titanium dioxide. These ingredients are insoluble particles which absorb and reflect UV away from the skin.