Sunscreen 101: The What, The When, and The How

WHAT TYPE OF SUNSCREEN SHOULD I USE?

Use a broad spectrum sunscreen which has both UVB (responsible for sunburn, tanning, and skin cancer) and UVA (responsible for extrinsic skin aging) protection. It should have an SPF of 30 or greater and should be water resistant. Check out Obagi Sun Shield Broad-Spectrum Matte SPF50

WHEN SHOULD I USE A SUNSCREEN?

Everyday, indoors or outdoors. Harmful UV rays can also penetrate window glass and visible light such as blue light from lamps, computer and mobile phone screens can exacerbate melasma and hyperpigmentation.  Snow, sand, and water increase the need for sunscreen because they reflect the sun’s rays.

HOW MUCH SUNSCREEN SHOULD I USE?

Most people only apply 25-50 percent of the recommended amount of sunscreen. The adequate amount to apply is 2 mg/cm^2 of skin (1/4 teaspoon for face, 1/2 teaspoon for face and neck, 1 teaspoon each for the arms) or equivalent to 30 mL (1 shot glass) for whole body application. Latest research shows that, with less application, SPF decreases linearly, not exponentially.  In other words, applying half the recommended amount gives you half the SPF.  So an SPF 50 becomes an SPF 25.

HOW DO I APPLY SUNSCREEN AND HOW OFTEN?

Sunscreen should be applied topically and correct administration is key to the effectiveness of use. A liberal uniform film of sunscreen should be applied, and the application should be 15 minutes before sun exposure. Sunscreen should be reapplied every 2 hours and after sweating or swimming. 

SHOULD I APPLY SUNSCREEN ON OTHER AREAS APART FROM THE FACE?

Don't forget to apply to the tops of your feet, your neck, your ears and the top of your head (if hair density is less or nil). Skin cancer also can form on the lips. To protect your lips, apply a lip balm or lipstick that contains sunscreen with an SPF of 30 or higher.