Summer is in full swing, and warm weather and longer days mean you'll probably spend more time outside. With this sunlight comes vitamin D, but also the risk of skin damage. Here's what happens when you don't protect your skin from the sun and measures you can take to do so.

How sun exposure affects your skin
Many people know that exposure to the sun increases the risk of skin cancer, but they don't really understand how it works. In fact, some people think their skin is naturally protected against sun exposure and they don't they need to do anything. This isn't completely wrong - the cells on your top-most layer of skin contain melanin, a pigment that protects against ultraviolet rays. Melanin isn't foolproof, however, and these rays can penetrate into deeper layers of the skin the longer you're outside.

Have fun outdoors this summer, but don't forget to protect your skin.Have fun outdoors this summer, but don't forget to protect your skin.

Brief exposure to ultraviolet light causes the melanin in your skin to darken. This is how tanning works and why freckles darken after a person spends time outside. The mildest sun damage leads to premature aging like fine lines and wrinkles, and the texture of your skin can change over time as it loses elasticity. 

It's also possible to get solar keratoses, also known as sun spots. These spots are common on areas that get a lot of sunlight, including the nose, cheeks, temples, neck and hands. They can be up to 20 millimeters across and often appear in groups.

Too much sun in one sitting results in a sunburn, especially for people with fair skin. While most sunburns turn your skin red and cause it to peel, a severe one makes your skin blister and gives you flu-like symptoms. Over time, sun exposure leads to skin cancer, one of the most common cancers worldwide. According to the Canadian Skin Cancer Foundation, 80,000 Canadians are diagnosed each year, and people today are at a higher risk than they were just a few decades ago. There are more cases of skin cancer each year than breast, colon, lung and prostate cancers combined.

What you can do to protect your skin
The most basic way to protect your skin is to avoid the sun, especially between 10 a.m. and 4 p.m. - when UV rays are at their strongest. This isn't always reasonable, of course, and everyone deserves a long day at the beach every once in a while.

This means your best defense is a broad-spectrum sunscreen with UVA and UVB protection. Dermatologists recommend you use one with a sun protection factor of at least 15, though some skin care companies offer sunscreens with SPF as high as 70. SPF 15 is plenty for the average person - according to Dr. Steven Wang of the Memorial Sloan-Kettering Cancer Center, it blocks 93 percent of UVB radiation. Sunscreen with an SPF of 30 blocks almost 97 percent.

In addition to sunscreen, you should wear wide-brimmed hats and loose, tightly woven clothing to protect your skin from direct sunlight. Also, keep in mind that sunscreen doesn't last forever. You'll have to reapply it approximately every two hours - or 80 minutes if you go swimming.

Enjoying your summer is all about taking advantage of great weather while still keeping safe. Your skin is important - it's your body's largest organ, so make sure you treat it well while you enjoy the outdoors.