Researchers have found that sunburn has been caused by the too much exposure to ultraviolet (UV) light. It is a sign that you have been out for too long under the sun. There is already enough damage that can be caused by UVA/ UVB rays and also there are some other things you need to know about this sunburn.
There is little or no way to completely avoid sun exposure, because our daily activities have us leaving the house everyday, for work, market church, events etc. So we really cannot help it. While at home at home Ultraviolet ray(UVA rays) can pass through windows and still be touching us even while inside the house.