Limiting Location Data Exposure

Basic cautions/mitigations on releasing location data.  From the NSA, a considerable recent update.  Instructive, but not meant to prevent data loss.   Via Schneier

Limiting Location Data Exposure
Mobile devices store and share device geolocation data by design. This data is essential to device communications and provides features—such as mapping applications—that users consider indispensable. Mobile devices determine location through any combination of Global Positioning System (GPS) and wireless signals (e.g., cellular, wireless (Wi-Fi®1), or Bluetooth®2(BT)). Location data can be extremely valuable and must be protected. It can reveal details about the number of users in a location, user and supply movements, daily routines (user and organizational), and can expose otherwise unknown associations between users and locations.

Mitigations reduce, but do not eliminate, location tracking risks in mobile devices. Most users rely on features disabled by such mitigations, making such safeguards impractical. Users should be aware of these risks and take action based on their specific situation and risk tolerance. When location exposure could be detrimental to a mission, users should prioritize mission risk and apply location tracking mitigations to the greatest extent possible. While the guidance in this document may be useful to a wide range of users, it is intended primarily for NSS/DoD system users. 

Mobile devices expose location data
Using a mobile device—even powering it on—exposes location data. Mobile devices inherently trust cellular networks and providers, and the cellular provider receives real-time location information for a mobile device every time it connects to the network. This means a provider can track users across a wide area. In some scenarios, such as 911 calls, this capability saves lives, whereas for personnel with location sensitivities, it may incur risks. If an adversary can influence or control the provider in some way, this location data may be compromised. Public news articles have reported that providers have been known to sell data, including near-real time location data, to third-parties [1].  ... "