Tan lines occur when the skin is unevenly exposed to sun's ultraviolet rays, causing lines of sun exposure to appear depending on the type of clothes worn. The areas of the body which have been covered stay healthy, while the damaged ones create lines of demarcation.
Wearing loose-fitting clothes, shedding clothes, avoiding peak hours and applying sunblock are some ways to prevent tan lines. Applying sunblock not only prevents discoloring of the skin and tan lines but also minimizes the risk of skin cancer. Peak hours refer to the time of day when the sun is most powerful and can damage the skin, typically from about noon until three in the afternoon.