A Sandbox With A Canopy is an excellent way to protect your children from the sun's harmful UV rays while they are enjoying their playtime. A canopy will give you the peace of mind that they are protected and it means that they can remain in their sandbox for as long as they want without fear of damage to their skin.
My wife grew-up in sunny, hot Australia where at one time not much attention was given to the ill effects of prolonged exposure to the sun. As they say: "that was then, and this is now". Australia has long since realized the correlation of skin damage and skin cancer and now broadcasts government advertising in prime-time TV spots, reminding people to be protected. Where my wife attended school it was even mandatory for school children to wear hats to and from school.
Here in North America we are also much more aware than we used to be and now take the appropriate measures to minimize, or eliminate potential future skin problems. This is especially true when it comes to our children, whether with hats, umbrellas, or sun screen.
Note the following statistics I found that support this point, particularly with children:
Remember that UV rays can still penetrate clouds, so be careful on bright cloudy days where you feel cooler but don't realize you are still exposed to the sun. This is also true of those sunny days when a cool wind is blowing and cooling you, making it seem as though the sun isn't as intense.
There are now a few covered sandboxes that also offer a canopy for protection from the sun. Not a bad idea.