Question: Is it true that some clothing will not protect my skin from ultraviolet light?
Answer: It's important to know that clothing can protect your skin from sunlight. Clothing can be used as ultraviolet light protection. Please note that jeans or a wool coat provides complete sunblock; a white T-shirt is different. A white T-shirt only provides a UPF (ultraviolet protection factor) of about five or six. It's also important to note that there are specialty fabrics out there that provide great UVB protection.
Those are available at outdoor retailers or in sports stores. These are known as wickable, dry-fit or dry-weave fabrics and were first embraced by the sports community but are now available to all those that are interested.