Nest Protect, the $99 smoke detector that returned to store shelves in June following a recall, is receiving a software update today designed to reduce false alarms. Version 2.0 of the Protect software will use the device's humidity sensor to better distinguish between smoke and steam, which the company says is responsible for more than half of false alarms. An accompanying update to the Nest app for iOS and Android includes a safety history that lets you see what caused alarms over the past days. It also allows you to modify the brightness of the protect's ambient light. The free update will roll out to customers over the next one to two weeks, Nest says.