Strava is a fitness app that uses devices enabled with Global Positioning System (GPS), such as the Fitbit, to record its users’ fitness statistics. It also recently released an anonymous heat map of its users’ GPS data on the Strava website.

A heat map is any representation of data that is organized on a map, with colors used to display data. This heat map shows where people who use Strava have been by displaying a line for each trip they take, creating criss-crossing trails that gather in greater quantity in cities and other places with a large number of users. While this heat map may seem rather benign, it has proven to be a potentially serious problem for the United States government.

The recent Strava heat map release has made it possible to identify some military outposts in the Middle East, as there is not much Strava activity there, making points of activity easy to see. According to the Indian Express, not only does this heat map allow people to find government buildings, but the map is detailed enough that some buildings and outposts can even be mapped. This may turn out to be dangerous for those who work for the government as the buildings in foreign nations may be targeted.     

The government has not made many statements on the matter of the heat map, but Defense Secretary Jim Mattis has said that the guidelines for the use of all wireless devices will be changed due to the recent release of the Strava heat map.

Although the release of the heat map cannot be undone at this point, changes in policy may be able to stop mistakes such as this from happening in the future, which will help keep employees of the United States government safe.

This has also spawned new debate about data privacy for individuals. Although Strava claims that its heat map data is anonymous and reveals only an aggregate of user data, individual users can be identified. This is especially true in areas with fewer users, where the Strava map can be compared to more detailed maps to locate the street address at the endpoint of one of the Strava lines.

With an increasing amount of data available to the public, privacy is becoming a growing concern. Research related to a variety of data sets has repeatedly shown that even when a company claims to store only anonymous and aggregated data, data related to specific individuals can often still be isolated.