An obvious but very important way to limit your exposure to UV light is to avoid being outdoors in direct sunlight too long. This is particularly important between the hours of 10 am and 4 pm, when UV light is strongest. If you are unsure about the strength of the sun’s rays, use the shadow test: if your shadow is shorter than you are, the sun’s rays are the strongest, and it is important to protect yourself.

UV rays reach the ground all year, even on hazy days, but the strength of UV rays can be different based on the time of year and other factors. The UV rays become more intense in the spring, even before temperatures get warmer. People in some areas may get sunburned when the weather is still cool because they may not think about protecting themselves if it’s not hot out. Be especially careful on the beach or in areas with snow because sand, water, and snow reflect sunlight, increasing the amount of UV radiation you receive. UV rays can also reach below the water’s surface, so you can still get a burn even if you’re in the water and feeling cool.

Some UV rays can also pass through windows. Typical car, home, and office windows block most of the UVB rays but a smaller portion of UVA rays, so even if you don’t feel you’re getting burned your skin may still get some damage. Tinted windows help block more UVA rays, but this depends on the type of tinting.