Sunshine is a wonderful thing. But it can also be a dangerous thing if exposure to it isn’t closely monitored. The Microsoft Band 2 UV Tile support page summarizes the dangers best:
UV stands for ultraviolet, a type of light in the sun’s rays. Tanning lamps and tanning beds also use UV light. Prolonged, unprotected exposure to UV light can damage your skin and eyes—potentially resulting in health problems such as cataracts—weaken your immune system, and cause skin cancer by mutating DNA.
Skin cancer is the most common form of cancer. According to the World Health Organization, between 2 million and 3 million non-melanoma skin cancers and 132,000 melanoma skin cancers occur globally each year. It’s also highly preventable with proper use of sunscreens and clothing coverage. Unfortunately, many people don’t take these precautions.
The Microsoft Band 2 features a UV monitor on the face of the metal clasp used to secure the watch (basically, the side of the watch opposite the screen). By exposing this monitor directly to sunlight, it can capture the current UV Index (a measure for how intense the UV radiation is) and give you recommendations for how best to handle exposure to the sun in that given time of day.
On the Band 2’s main menu, tap the UV Tile, conspicuously enumerated by an icon with the letters “UV” on it, press the action button as instructed, and face the UV monitor (the bottom side of the Band) against the sun for a few seconds. Annoyingly, it doesn’t vibrate or give you any indication the device is done sampling, but I’ve found that 10 seconds should be more than enough.
In comparing the Band 2’s deductions with data gathered from my city in my phone’s Weather app, the Band 2’s result does seem to be accurate.
The UV monitoring function also provides you the option to periodically remind you of the current exposure as time goes on. Swiping to the left within the UV menu provides the option to turn on the UV reminder. As you go about your business under the sun, the UV monitor will continue monitoring your UV exposure as best it can, and remind you periodically (determined by the Cadence interval you’ve set) to keep on top of your UV protection.
From my experiences thus far, this function reminds only if necessary. When I stayed under the shade for prolonged periods, way past the 30 minute cadence I’ve set for it to remind me, it didn’t say a word. Only moments after I restored balance to the force did it suddenly remind me to put on more protection. So it works, and seems smartly designed at that.
My experiences suggest that the UV monitor is constantly sampling sunlight when the reminder is on. It’s not entirely clear to me if it continues this sampling while the reminder is off, as such I can’t quite gauge if leaving the reminder on drains more battery life than off.
All told, the Microsoft Band 2’s UV monitoring seems to be fairly robust and a great way to methodically keep track of UV exposure and protection during the day.