The regular and correct use of broad-spectrum sunscreens is the key part of a program to prevent sunburn, sun damage and skin cancer. Probably the biggest problem with sunscreens is that people don't really know how to use them correctly. Recent studies indicate that people don't use sunscreens as frequently as they should and also don't apply a sufficient amount. Labels of most sunscreens call for 'liberal and frequent' applications. That's more than most people put on.
Timing is important, too.
To have the best effect, sunscreens need to be applied 30 minutes before you get to the pool or beach, not after you arrive. And, people should reapply even water-resistant sunscreens every 90 minutes. Therefore, tanning beds are not safe - they are a factor in skin cancer and should be avoided. They also can be associated with other nasty skin problems, such as infections and warts. We know that sunburns and UVB are associated with skin cancer and melanoma risk.