What is the difference between UVA and UVB rays?
UVA rays are the rays that cause premature aging and long-term sun damage. They can pass through glass (like car windows), and are present all year round. They are not changed by weather or altitude, and are 20 times more abundant in the atmosphere than UVB rays. UVB rays are the rays that cause burning. These rays cause sunburns or tanning and vary with the seasons…for example, UVB rays are more abundant in the summer. UVB rays increase at high altitudes and near the equator, and they make up only 5.0% of the sun’s rays. The SPF factor on sunscreen labels only indicates the level of protection from UVB rays, and the FDA is working on new labeling requirements that will help consumers measure the amount of UVA protection offered. UVB rays are related to 90% of non-melanoma skin cancers and have been linked to cataracts.
