After the Internet was awash with reports that tattoos can negatively affect the Apple Watch's heart rate sensor, Apple has confirmed the issue on its website. In a page dedicated to explaining how the Watch captures your vitals, the company notes: "Permanent or temporary changes to your skin, such as some tattoos, can also impact heart rate sensor performance," adding that "the ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable readings."

http://www.engadget.com/2015/05/01/a...-confirmation/