To achieve beautiful healthy skin, you must protect yourself from dangerous enviromental factors that can contribute to premature aging, skin diseases and skin cancer. A poor diet, bad digestive function, liver malfunction, excessive sun exposure, and smoking are the biggest causes of unhealthy skin. Below you can find ways to best shield your skin and maintain your health.

SPF - What it Means

SPF (sunscreen protection factor) tells you how long you can stay in the sun before getting burnt. If you usually burn after 10 minutes in the sun and you're wearing an SPF 20 sunscreen, the formula works as follows: 10 minutes X 20 SPF = 200 minutes. Keep in mind that you'll need to apply sun block more frequently if you're perspiring or get wet. Rule of thumb: wear a product with an SPF of at least 8 every day, even on cloudy days.

Sunscreen Shelf Life

Always check the label of your sunscreen to determine its shelf life. Most sunscreens without expiration dates are good for two to three years. Store sun block in a cool, dry place; extreme heat may decrease your sunscreen's shelf life. Also, if you notice any color, odor, or consistency change in your sunscreen, throw it out! Your skin is worth every bit of the $10 you'll spend on a new bottle of sun block.