A statement on Apple’s support page warns users that iPhones contain magnets and radios that emit electromagnetic fields and “might interfere” with medical devices such as implanted pacemakers and defibrillators. “To avoid any potential interactions with these devices, keep your iPhone and MagSafe accessories a safe distance away from your device (more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly charging).”
The iPhone 12 comprises a circular array of magnets around a central charging coil that makes it compatible with MagSafe, which has a magnetometer and a single-coil near field communications (NFC) reader. The magnets help to align the iPhone on a wireless charger, thereby increasing wireless charging speeds.
Implantable cardioverter-defibrillators (ICDs) have electric and magnetic components that respond to an externally applied magnetic field. When an external magnet is applied to a defibrillator, the life-saving high voltage shock therapy provided by the ICD can be suspended.
A team of doctors tested this interaction on a patient with a Medtronic ICD with an iPhone 12. When the iPhone12 was brought close to the ICD over the left chest area, immediate suspension of ICD therapies was observed and persisted for the duration of the test. This result was reproduced multiple times with different positions of the phone above the pocket.
Apple claims that though all iPhone 12 models contain more magnets than prior iPhone models, they don’t pose a greater risk of magnetic interference to medical devices than prior iPhone models.