Apple has acknowledged that it collects batches of precise user location data from owners of its mobile and computer products but says users can keep themselves from being part of the data collection.
In a response to questions about its data collection practices from two congressmen, the Cupertino, California company said users can turn off services that record their location, and noted that the information it collects is not directly linked to users' names or individual devices.
Apple's answers came in a document released by Reps. Edward Markey, D-Mass., and Joe Barton, R-Texas, who sent the electronics maker a list of questions last month after The Los Angeles Times published a report pointing to the company's practice of collecting, storing and sharing the "precise," "real-time geographic location" of users' mobile devices.
Apple said user location information cannot be collected unless a user has the device's location-services - and location-based applications - turned on.
Applications such as Google Maps and Yelp use location data to give users driving directions and restaurant recommendations.
But once a user has accepted those terms the first time, the company can collect and store the data as well as share them with certain partners.
In those cases, Apple collects "batched" sets of location data from user devices once every 12 hours. Devices with GPS chips - like all recent-model iPhones - know their position based on satellite signals, and others can triangulate their location using data about nearby cellular towers and Wi-Fi access points.
Markey and Barton thanked Apple for sharing basic information about its use of location data but noted that industry practices in that area have been less than transparent.
"The new challenges and concerns that present themselves with the collection and use of location-based information are particularly disconcerting," Barton said in a statement.
"While I applaud Apple for responding to our questions, I remain concerned about privacy policies that run on for pages and pages."
When the latest version of the iPhone operating system was released in late June, users found that the list of terms and conditions that contained the updated privacy policy for iPhone and App Store users ran on for more than 40 pages.
In its answers to the lawmakers, Apple noted that location data were gathered only when consumers used iPhone applications that required a location.
The company did not store precise data for its advertising service, iAd. Instead, it converted the device's precise location into a ZIP code, it said.
Observers have noted that removing a user's name from highly precise data, such as location co-ordinates, may not always allow for true anonymity, as individual travel and movement patterns are often unique.
In response to questions about the way Apple anonymizes location data, company spokesman Steve Dowling referred The Los Angeles Times back to Apple's written response to the congressmen.
